Systems Test

All pubs are available from the electronic bookbag The system pub is of course the official source and so you can download a copy by clicking here---> [[media:P-402.pdf.zip]]. The nice thing about the paper version is you can highlight stuff. The nice thing about the electronic version is it's searchable. =THE SYSTEMS ENABLING OBJECTIVES= From CNATRA P-402 (Rev. 7-98) THE SYSTEMS ENABLING OBJECTIVES From CNATRA P-402 (Rev. 7-98)

CHAPTER 1
INTRODUCTION TO THE TH-57

1.1. Described the basic design characteristics and capabilities of the TH-57 helicopter.

Land-based, skid-configured, utility type helicopter, designed to land and takeoff from reasonably level terrain. A Rolls Royce (formerly Allison) 250C-20J turboshaft engine powers the main rotor, which is used for lift and thrust, and the tail rotor, which is used to counteract torque and provide yaw control. The maximum takeoff Gross weight is 3,200 lbs. The maximum forward air speed at sea level standard day is 130 kts, maximum sideward airspeed is 25 kts and maximum reward airspeed is 15 knots.

Dimensions
 * Main rotor diameter:	33’-4”
 * Main rotor to ground clearance:	11’-7.5” / 6’-5”
 * Main rotor to tail boom clearance:	1’-1.5”

1.2. Recognize the five major sections of the airframe.


 * 1. Forward / cabin
 * 2. Landing gear
 * 3. Cowling
 * 4. Tail boom
 * 5. Vertical fin

1.2.1. Recognize the items associated with the forward section.

Construction
 * Primarily constructed of aluminum honeycomb covered with either fiberglass or aluminum skin. Provides excellent weight-to-strength ratio and also helps sound proof that cabin area.

Battery compartment, windshield, control column, cockpit, passenger compartment, upper cabin deck, baggage compartment, aft electrical compartment, aft cabin space.

1.2.2. Identify the components of the landing gear.


 * 1. 2 aluminum alloy curved cross tubes
 * 2. 2 aluminum skid tubes
 * 3. formed steel tail skid
 * 4. tow rings
 * 5. replaceable skid shoes
 * 6. ground handling wheels

1.2.3. State the main purpose of the cowling section.

Streamlines air flow to reduce drag

1.2.4. State the purpose of the tail boom, and identify its associated parts and their functions.

The tail boom provides an extended support to mount the tail rotor and vertical fin (By increasing the moment arm of the tail rotor it allows the size of the tail rotor to be smaller than the main rotor). The tail boom is mounted to the forward section via a mounting pad and four bolts.. Horizontal Stabilizer: Negative camber pushes the tail down to allow near level forward flight. 1.2.5. Described the purpose of the vertical fin and state how it provides directional stability and reduces tail rotor loads.

Construction
 * Semi-monocoque made of aluminum honeycomb and aluminum skin mounted at a 5.5o offset from the longitudinal axis.

Purpose
 * Provides directional stability and reduced tail rotor loads at cruise airspeed. This is accomplished by a 5.5o offset from the longitudinal axis.  This offset provides a horizontal lift component that assists in countering torque. (The greater the airspeed, the greater the lift.)

1.3. Identify the components of the cargo hook assembly with its associated capabilities and limitations. Components
 * 1. Frame
 * 2. Hook assembly
 * 3. 1 Electrical and 2 manual (one in the cockpit and one on the hook assembly) release

Capabilities and Limitations
 * Structural weight capacity of 1500 lbs

1.4. Described aircraft lighting system and identify the associated lights, switches, and circuit protection.

Exterior lights
 * 1. Position Lights: Controlled by 3 switches on the overhead panel:  On / Off, Bright / Dim, and Steady / Flashing.  On the ground at night during periods of low rotor RPM use Flashing / Bright to signal other aircraft not to taxi near you.
 * 2. Anti-Collision lights: 2 lights controlled by a single overhead switch (On / Off): Top of vertical fin and below fuselage aft of the baggage compartment.  Circuit protection is provided by the anti-collision circuit breaker type switch located on the overhead console.
 * 3. Landing Light: controlled by a single overhead switch.  Light is located just aft of forward cross tube.  CAUTION:  10 minute operating limitation due to fire hazard.
 * 4. Search Light: Controlled by 2 switches on the pilot’s collective.  On / Off / Stow Switch: CAUTION Once the automatic Stow cycle is complete the switch should be turned OFF.  If left in Stow a faulty heat switch may cause the extend / retract motor to burn out.  Directional Control Switch:  The light is adjustable from 0o  to 120 o of extension.  From 0 o to 60 o the light will rotate 90 o left or right.  From 60 o to 120 o the light will rotate 360 o.  Circuitry is protected by two circuit breaker, labeled SEARCHLIGHT POWER and SEARCHLIGHT CONT.

Interior Lights
 * 1. Instrument Lights – Controlled by overheat On / Off Rheostat. This does not control all Cockpit lights:  Caution Panel has it’s own Bright – Dim switch.  UHF Control has it’s own Dim switch as well.
 * 2. Cockpit Lights – 2 Grimes lights mounted on the control column.
 * 3. Cabin Lights – 2 overhead lights

1.5. Identify the seat restraints, doors, and caution panel within its associated capabilities and limitations.

Seat Restraints
 * Pilot and copilot seats are equipped with a lap safety belt and inertia reel shoulder harness with a manual lock-unlock handle. The reel will automatically lock when the helo encounters a longitudinal impact and a deceleration force of 2 to 3 G’s.

Doors
 * Both cockpits are accessed via forward hinged doors that are jettisonable in the event of an emergency landing or are removable during the execution of external lifts.

Caution Panel
 * The caution panel is located on the instrument panel. Illumination of any of the lights on the caution panel alerts the pilot to a system fault or condition.  The caution panel is powered by ESS #2 BUS and is protected by the CAUTION LT circuit breaker.

CHAPTER 2
ROLLS ROYCE 250C–20J TURBOSHAFT ENGINE

2.1. Identify the type of gas turbine engine use in the TH – 57.

Rolls Royce 250C-20J series turboshaft engine. This engine is an internal combustion gas turbine engine featuring a “free” power turbine consisting of a combination axial-centrifugal compressor; a single “can” type combustor; a turbine assembly which incorporates a two-stage power turbine and exhaust collector; and an accessory gear box which incorporates a gas producer gear train and a power turbine gear grain.

2.1.1. Stated the power output of the 250C–20J engine.

Rolls Royce's 250C-20J engine is a 420 SHP engine derated by Bell Helicopter to 317 SHP due to power train limitations.

2.2. Identify the four sub-assemblies of the engine.


 * 1. Compressor Section
 * 2. Accessory Gearbox Section
 * 3. Turbine section
 * 4. Combustion Section

2.2.1. Identify the four sub-assemblies of the compressor.


 * 1. Front Support
 * 2. Compressor rotor wheels and blades
 * 3. Case Assemblies
 * 4. Diffuser Scroll

2.2.1.1. State the three functions served by the front support of the compressor and identify how each function is achieved.


 * 1. Hollow struts serve a part of the anti-ice system- 500oF air from the diffuser scroll is channeled into the struts via the anti-valve. This heated air prevents the inlet vanes from cooling to the point of freezing.
 * 2. Struts serve as inlet guide vanes, ensuring ambient air strikes the first stage compressor at the proper angle.
 * 3. Support the forward end of the compressor shaft via bearings and struts.

2.2.2. Described the compressor used in the 250C–20J engine by identifying the components, the types of compression utilized, the number of stages of compression used, and where the components are mounted.

Compressor: A 6 stage axial compressor (rotor followed by stator) followed by a single stage centrifugal compressor provides a compression ratio of 6.5 to 1 and a temperature of 500oF. (The compressor bleed air valve is located at the 5th stage of axial compression)

Diffuser Scroll: Mounted on output of centrifugal compressor; used to direct air from compressor to the Air Transfer Tubes. Houses 4 bleed air taps:
 * 1. Anti-Ice
 * 2. Cabin Heating
 * 3. Fuel Control / Nf Governor control Air
 * 4. Compressor Bleed Air Valve Control Air

Air Transfer Tubes: Transfers air from diffuser scroll to combustion section.

2.2.3. State the main purpose of the compressor bleed air system.

Bleeds air from the 5th stage of the compressor during starting, acceleration, and at low compressor pressure ratio operation to prevent / minimize compressor stalls and surging.

2.2.3.1. Identify the location of the compressor bleed air system.

Compressor bleed air valve is located at the 5th stage of axial compression, approx. 2 ‘o clock.

2.2.4. Trace the path of air flow from the air intake through the engine by identifying the components in the proper sequence with respect to flow.

Ambient air enters the front support and is guided by the vanes to strike the first stage compressor rotor at the proper angle. The rotor accelerates the air and directs it to the stator which slows the air, increasing static pressure. The stator then directs the air to the second stage rotor. This process continues through the six stages of axial compression. At the 5th stage the compressor bleed air valve bleeds air as necessary to prevent a compressor stall. After the 6 stages of axial compression, air enters the centrifugal compressor (1 stage). After the single stage of centrifugal compression air is collected, in the diffuser scroll (6.5 times compression, 500oF) and a portion is bled off (Bleed Air Valve Control Air, Cabin Heating, Anti-Icing, Fuel Control / Nf Governor Control Air).

The remaining air is directed from the diffuser scroll to the combustion section via the air transfer tubes. In the combustion section 75% of the air is used for combustion cooling and the remaining 25% is mixed with fuel for combustion.

The hot expanding gasses from the combustion section move forward to the 4 stage turbine section. First the gasses reach the 2 stage Gas Producer turbine assembly (Ng). The gasses are accelerated by the 1st stage nozzle and then directed to the 1st stage turbine wheel which converts heat energy to mechanical energy. The 2nd stage of the gas producer turbine identical to the 1st (Nozzle followed by the turbine wheel). The 2 stage Gas Producer turbine assembly extracts 2/3’s of the available energy from the hot expanding gases and drives the compressor section and the Ng drive train. The hot gases exit the Ng turbine and pass over 4 TOT thermocouples which sense the temperature and send an averaged signal to the 28v DC TOT gauge on the instrument panel. After the 4 TOT Thermocouples the gases continue forward to the 2 stage Free Power Turbine (Nf) which consists of two sets of Nozzle then wheel pairs. The Nf extracts the remaining 1/3 of energy from the gases to drive the Nf gear train.

The remaining exhaust gases are collected in the exhaust collector and then out the twin exhaust.

2.2.5. Identify the type of combustor used in the 250C – 20J engine.

Single Can Type

2.2.5.1. Identify the location of the components in the combustion section and state their purpose.

Outer Case and Inner Liner: Provides thermal separation from the combustion chamber and the exterior of the combustor section. Also provides a flow path for cooling air from the Air Transfer tubes.

2.2.5.2. State the purpose of air flow through the combustion section and amount used for each purpose.

75% for cooling, 25% for combustion

2.2.6. State the purpose of the turbine section in the 250C – 20J engine.

Converts heat energy to mechanical energy

2.2.6.1. Identify the components of the turbine section and state their function.


 * 1. 2 stage Gas Producer Turbine: Drives the compressor and Ng gear train.
 * 2. 2 stage Free / Power Turbine: Drives the Nf gear train.
 * 3. Thermocouple Assembly: 4 thermocouples provide signal to TOT gauge

2.2.6.2. State what portion of the available energy is used to drive the gas producer and free power turbine sections.

2.2.6.3. Identify the location and name of the components used for measuring turbine outlet temperature (TOT).
 * 2/3’s Compressor and Ng drive train	(51,989 rpm at 100%)
 * 1/3 Nf drive train			(33,956 rpm at 100%)

System Requires 28v DC
 * 4 TOT thermocouples between the Ng and Nf turbines
 * TOT indicator circuit breaker
 * TOT gauge
 * TOT Light (Comes on when START limits are exceeded. Maintenance must reset with a key in the battery compartment)

2.2.7. Identify the functions of accessory gear box.

Primary structural member for the engine. Provides mount for compressor and turbine sections and 4 engine mounts (3 used to mount the engine, 4th used to mount the anti-ice motor)

2.2.7.1. Identify the accessories driven by the gas producer.


 * Starter Generator
 * Tach generator (Ng)
 * Oil Pump (Shares the same shaft as the Ng Tach)
 * Fuel Pump
 * Fuel Control Unit
 * Standby Generator

2.2.7.2. Identify the units driven by the power turbine gear train.


 * Governor, Nf
 * Output Shaft
 * Tach generator (Nf)
 * Torque meter

2.3. Identify the type of engine oil system utilized in the 250C – 20J.

Pressurized, circulating, dry-sump system (Dry sump, meaning oil reservoir is located separately from the oil pump.)

2.3.1. State the function and location of each component of the engine oil system.

5.5 quart oil reservoir: Holds engine oil and provides mount for the oil temp bulb.
 * Oil Pump: Located inside the accessory gear box, driven by same shaft which drives the Ng tach generator.  Spur gear oil pump with 1 pressure and 4 scavenge elements.  Delivers oil under pressure the Internal Oil Filter Assembly.
 * Internal Oil Filter Assembly: Contains Pressure Regulating Valve, Filter Element, and Differential Pressure bypass valve.
 * Gearbox Housing and Oil Pressure Sensing Port: Delivers signal via wet line to the Oil Pressure Gauge.
 * Airframe External Oil Filter: 10 micron pleated paper, bypass type filter.
 * Temperature Control Valve: Located near the Airframe External Oil Filter. Cool oil is sent back to the reservoir.  At 71oC 160oF valve begins to open and allow hot oil to flow through the radiator type cooler.
 * Radiator Type Cooler: Cooled by air from the squirrel cage fan, which is driven off of the tail rotor shaft.  This same air is ducted and sent forward to cool the transmission oil and hydraulic fluid.

2.3.2. Identify how to determine the engine oil level and why it is important to know the exact level.


 * Sight gauge: Located on the Stbd. side of the Oil Tank.
 * Dipstick / Filler Cap: Located on Port side of the Oil Tank. This is the only way to know the exact amount. This is important because if freewheeling unit oil seal fails, transmission oil under pressure will enter the accessory gear box (which is not under pressure) and cause and overfill condition.

2.3.3. State how engine oil temperature and pressure information is transmitted to the cockpit.


 * Temperature: 28 v DC oil temp bulb located in the oil tank.
 * Pressure: Wet line from pressure sensing port (downstream of internal filter)

2.4. State why fuel metering is important for a turbo shaft engine by identifying the problems which can occur if fuel is not metered correctly.

Excessive temperature, Compressor Stall, Rich or Lean Blowout

2.4.1. Identify the type of fuel control used in the 250C–20J engine and state how it controls engine power.


 * Ng Fuel Control Unit: Ng gear train drives flyweights which meters fuel. During Start compressor discharge pressure is used to meter fuel.
 * Nf Governor: Varies bleed air control line air pressure which goes to the Ng Fuel Control which in turn varies fuel to the engine.

2.4.2. Described the function of the power turbine governor by stating the engine performance parameters sensed and its connection to fuel control.

Twist Grip Must be full open and Nf gear train up to speed. Nf gear train drives fly weights which varies compressor discharge air pressure which is set to the FCU and used to meter fuel.

2.4.3. State what components control the power turbine governor and gas producer fuel control.

Twist Grip Position, compressor Discharge Pressure, Ng speed, Nf speed, Nf Governor RPM Beep switch which controls the linear actuator which controls the Nf governor.

2.4.4. State how the twist grip functions.

3 positions: Fuel Off, Flight Idle and full open

2.4.5. Described the droop compensation system by identifying the cockpit controls, engine controls, and its effect on power output.
 * Collective position controls Nf governor throttle lever position which changes flyweight tension which changes compressor air pressure signal which controls the fuel control unit. This allows the fuel control unit to anticipate power changes based on collective position.

CHAPTER 3
FUEL SYSTEM

3.1. State the major components of the fuel system and their functions.


 * 1. Fuel Cell – (91 gal new B & all C; 76 gal Old B)
 * 2. 2 fuel boost pumps – Prevents vaporization in the fuel lines above 6000 ft PA by pressurizing the line at 4-30 psi.
 * 3. fuel quantity measuring system – 2 floats, 1 gauge calibrated in Gal. Fuel Low Warning System: 20 Gal fuel low switch and Caution light
 * 4. Pressure Indicating system – Each fuel boost pump has a 3.5 psi pressure switch and they both are connected to Caution light. A fuel pressure transducers located between fuel cell and fuel shutoff valve and sends a signal to the fuel pressure gauge.
 * 5. Shutoff Valve – 28 v dc shutoff valve with a thermal relief feature located just above fuel cap in main fuel supply line. If DC power is lost it will stay in the last energize position.
 * 6. Airframe fuel filter – Impending Bypass function, trips caution light.
 * 7. Engine Fuel pump / Filter – Low pressure (4-30 psi) bypassable filter element filters fuel and delivers it to the pump which pressurizes the fuel (650-750 psi) and since it to the Ng fuel control unit.

3.1.1. Identify the characteristics of the fuel cell.


 * Single bladder-type fuel cell, located below and aft of the passenger seat, is crash resistant, but not self-sealing.

Capacity
 * 91 Gal (late model B’s and all C’s)
 * 76 Gal (early B’s BUNO 161XXX)

3.1.2. Identify the methods used to re-fuel the fuel cell.


 * Early B’s – Gravity fueling only
 * Late C B’s and all C’s – Gravity and Pressure fueling. (40 psi max press)

3.1.3. State how the fuel boost pumps and their components work to supply fuel to the engine and information to the pilot.

Two pumps (4-30 psi), connected in parallel, energized anytime the 28 vdc boss is energized. Each plant has a 3.5 psi pressure switch to indicate failure to a common FUEL PUMP Caution Light.

3.1.4. Identify the various fuel pressure limitations and the associated operational restrictions.

Allowable fuel boost pump pressure limits are 4-30 psi. Fuel pump light comes on when either pump pressure falls below 3.5 psi. If one fuel boost pump fails the fuel pressure gauge will still read 4 – 30 psi, if both pumps fail the gauge will read 0 psi. If either (or both) fuel pump(s) fail you must descend below 6000’ PA. Minimum usable fuel becomes 20 gal.

3.1.4.1. Identify the various pages, switches, etc., that relay pressure information, along with their limitations.

FUEL PRESSURE GAUGE: Scale is 0-30 psi. Normal range is 4-30 psi. A fuel pressure transducer sends a signal to the gauge. NOTE: VHF transmission may cause pressure gauge to fluctuate if helo has a solid state fuel pressure transducer due to EMI.

FUEL BOOST PUMP PRESSURE SWITCH: 1 on each boost pump; activates fuel pump caution light if pump pressure falls below 3.5 psi.

AIR FRAME FILTER CAUTION LIGHT: When differential pressure is sensed across the airframe fuel filter the caution light comes on to warn the pilot of an impending bypass.

LOW FUEL CAUTION LIGHT: Comes on when fuel is approximately 20 gal.

3.1.5. Identify the components and characteristics of the fuel quantity measuring system.


 * 2 float type sensors provide inputs to a single fuel quantity indicator (calibrated in gallons, 0-100)
 * 1 float type switch activates fuel low caution light when fuel drops to approximately 20 gallons.

3.1.6. State how the pressure indicating system works to relay fuel pressure information to the pilot.

Fuel pressure transducer, located between boost pumps and fuel shutoff valve, sends a signal to cockpit to indicate fuel boost pressure. (28 vdc)

3.1.7. State how shut-off power works to permit or restrict fuel flow.

28 vdc system. Shutoff valve is located in main fuel supply line in fuel compartment just above fuel filler cap. Controlled by cockpit switch. When DC power is lost the valve stays in the last energized position.

3.1.8. State the location of the airframe fuel filter and identify the functions of its components.

Located on STBD side, aft of the forward firewall and consists of: Replaceable filter element, drain valve, bypass valve, impending bypass switch, manual test button.

3.1.9. State the operational characteristics of the engine fuel pump/ filter.

Delivers filtered fuel at 650-750 psi to the fuel control unit. NOTE: Fuel enters pump housing and passes through a low pressure filter (4-30 psi) and then to the gear type pump which pressurizes the fuel to 650-750 psi and delivers it to the FCU. The internal filter will bypass if clogged but there is no indication until maintenance inspects the filter. The FCU meters the proper amount of fuel and sends it to the fuel nozzle. Any excess fuel hot needed by the fuel control unit is returned to the engine driven fuel pump.

CHAPTER 4
TH-57B/C POWER TRAIN

4.1. Identify the components of the TH–57 power train.


 * 1. Transmission
 * 2. Engine drive shaft (Barbell Shaft)
 * 3. Freewheeling Unit
 * 4. Forward short shaft
 * 5. Oil cooler fan driveshaft
 * 6. Aft short shaft
 * 7. 6 tail rotor drive shafts
 * 8. Tail rotor gear box

4.1.1. State the type of lubrication system utilized in the main transmission.

Wet sump, pressure lubrication system

4.1.2. Identify the components of the main transmission oil system.


 * 1. Wet sump: Lower portion of transmission case (5 quart capacity)
 * 2. Oil Pump: Driven by transmission accessory drive (also drives Hydraulic power pack: pump and Nr tach Gen) mounted internally
 * 3. Oil filter Head Assembly:
 * a) High Temp Sensor: 110oC turns on caution Light
 * b) Temp Bulb:  Sends signal to temp gauge on instrument panel
 * c) Oil Bypass Valve: Bypasses filter when clogged
 * d) Oil Monitor: Magnetic screen type chip detector (not part of Chip detector Caution Light system.)
 * 4. Drain Valve: Self explanatory hopefully
 * 5. Oil Cooler: Radiator type cooler with temperature bypass feature when oil is cold. Cooling air  supplied by the squirrel cage fan.
 * 6. 2 pressure jets: Sprays oil on transmission gears and bearings. A tee fitting between the two jets supplies oil to the freewheeling unit and sends oil to the wet line pressure gauge on the instrument panel and the low pressure switch.
 * 7. Oil pressure regulator: Allows maintenance ot adjust oil pressure

4.1.2.1. State the function of each component of the transmission oil system.

See 4.1.2

4.1.3. State the location of the barbell shaft.

Between transmission and freewheeling unit

4.1.3.1. State function of the barbell shaft.

Transmits power from freewheeling unit to transmission and has a flexible splined coupling on each end which gives it its barbell shape. The flexibility if these couplings allows for momentary misalignment of the shaft, cause by movement of the transmission durring flight.

4.1.4. State function and location of the freewheeling unit. (AND) 4.1.4.1. State the source of lubrication for the freewheeling unit.
 * Mounted to the front of the accessory gear box. The freewheeling unit housing serves a an oil sump and holds the magnetic chip detector (not electrical and not part of the chip light system).  The freewheeling unit is composed of an outer race which is splined to Nf turbine output gear and an Inner race which connects to the Barbell shaft and Tail Rotor Drive Shaft.  Between the tow races is the sprag clutch which disconnects the power train from a failed Engine.

4.1.5. Identify the components of the tail rotor drive shaft.


 * 1. Steel Forward Short shaft
 * 2. Steel Oil Cooler Fan Driveshaft
 * 3. Aluminum Aft Short Shaft
 * 4. 5 Aluminum Tail Rotor Drive shafts
 * 5. Tail rotor Gear Box (Magnesium which changes direction of drive by 90 degrees and provides gear reduction from 6000 rpm to 2554 RPM (2.35:1)

4.1.5.1. State the function of the tail rotor drive shaft.

Serves as part of the tail rotor drive train and as it turns it also turns the squirrel cage fan which in turn cools engine oil, transmission oil and hydraulic oil.

4.1.6. State the two functions of the tail rotor gear box.

Changes direction of drive by 90 degrees and provides gear reduction from 6000 rpm to 2554 RPM (2.35:1)

4.1.7. Identify the type of lubrication system utilized in the tail rotor gear box.

Self contained splash type. 3/8 pint capacity, contains an electrical chip detector wired to a T/R CHIP caution light.

CHAPTER 5
MAIN ROTOR, TAIL ROTOR, AND FLIGHT CONTROL SYSTEM

5.1. State the major components of the main rotor system.


 * 1. Splined trunnion
 * 2. Yoke
 * 3. Tension torsion-straps
 * 4. Blade grips
 * 5. Pitch change horns
 * 6. Flap restraint assembly (kit)
 * 7. Main rotor blades

5.1.1. Described the design of the main rotor system.

Two bladed, semi-rigid, flapping type with an underslung hub

5.1.2. State the purpose of the splined trunnion.

Provides the flapping axis for the main rotor and a mounting point for the yoke assembly.

5.1.3. State the type of mounting used between the trunnion and mast of the main rotor.

Splined mounted to the mast

5.1.4. State the purpose of preconing.

2.25o of preconing, helps relieve bending stress of he yoke, blade grips, and root of main Rotor Blades.

5.1.5. State the purpose of the tension torsion strap.

Connects blade grips to the yoke assembly and absorb centrifugal forces while allowing for twist to permit pitch change action.

5.1.6. Described the purpose of the latch bolt.

The horizontal latch bolt connects the blade grips to the tension torsion strap.

5.1.7. Described the method used to ensure high rotational inertia for autorotations.

During construction weights are added to the tip and mid-span of each main rotor blade.

5.1.8. State the purpose of the flap restraint kit. Limits the amount of flapping at low rotor RPM (below 25-32% Nr)

5.1.8.1. Described the operation of the flap restraint kit.

At low RPM, springs hold the restraint arms in place and prevent excessive flapping. As RPM increases, flyweights overcome spring tension (at 25-32% Nr) and restraint arms move allowing full flapping motion.

5.1.9. State the need for a rotor break.

Provides a means of rapidly decelerating the rotor after engine shutdown for personnel and aircraft safety.

5.1.9.1. Differentiate between the TH-57 hydraulic system and the rotor break hydraulic system.

Totally independent of each other. Rotor brake uses a hand operated master cylinder (100-120 psi).

5.1.9.2. State type and location of the gauge associated with the TH-57C rotor break.

Direct reading gauge located overhead between the pilots.

5.2. State the function of tail rotor system.

To compensate for the torque effect of the main rotor and to allow control of the helo about he yaw axis.

5.2.1. Describe the tail rotor system.

2 stainless steel blades, semi-rigid, flapping type system (5’-5” in Dia)

5.2.2. Identify the major components of the tail rotor system.


 * 1. Stainless Steel Rotor Blades
 * 2. Pitch Change Horns
 * 3. Cross Head
 * 4. Control Tube
 * 5. Balance Wheel
 * 6. Static Stop
 * 7. Yoke Assembly

5.2.2.1. Describe the construction of the tail rotor blades.

Aluminum honeycomb covered by stainless steel skin. Stainless steel doublers added at the foot for added strength. Stainless steel leading edge abrasion strips. Root end has an aluminum alloy retention block which houses two spherical bearings to mount the blade to the yoke.

5.2.3. State the purpose of the blade doublers.

Added Strength

5.2.4. State the purpose of the balance wheel.

Weights are added to the holes in the wheel to Dynamically Balance the tail rotor.

5.2.5. Identify the component which limits tail rotor flapping.

Static Stop mounted to the gearbox output shaft

5.3. Identify the type of flight control systems used on the TH-57.

Conventional type mechanical flight control system

5.3.1. Identify the three flight control systems.

Cyclic, collective, anti-torque pedals

5.3.2. State the purpose of the cyclic control.

A cyclic control input will result in the rotor disc tilting and the aircraft moving in the direction of the control input.

5.3.2.1. Describe the sequence of events with a cyclic input.

As the cyclic moves it causes the pivot support to move. Pilot and copilot pivot supports are inter-connected by a torque tube. A yoke assembly connects to the top of each pivot support and transmits the cyclic input to the mixing lever located at the base of the control column. The mixing lever transmits the mixed (fore / aft with left/ right) cyclic input to the cyclic hydraulic servos ant the stationary swashplate. The hydraulic servos boost the mechanical input. The stationary swashplate tilts and there fore transmits the cyclic input to the rotating swashplate which tilts and provides input to the pitch change horns via the pitch change rods. NOTE: The stationary swashplate is mounted on the uniball which his what allows the stationary swashplate to tilt in any direction.

5.3.3. Identify the type of boost used with the flight controls.

Hydraulic Boost

5.3.4. State the purpose of the collective control.

The collective changes the pitch on both main rotor blades equally and in the same direction to give vertical control of the helo.

5.3.4.1. Described the sequence of events with a collective input.

The collective is connected to a jackstaff which is where the friction adjuster is mounted. Collective control inputs are transmitted through a lever assembly and control tube up to the hydraulic servo and the collective lever (item with “Top” on it in preflight). As the pilot pulls up on the collective, the collective lever is puled down. This will raise the pivot sleeve and uniball assembly and therefore raise the stationary and rotating swashplates which will increase the pitch equally on both main rotor blades via the pitch change rods and pitch change horns.

5.3.5. State the purpose of the anti-torque tail rotor.

To compensate for the torque effect of the main rotor and to allow control of the helo about the vertical axis.

5.3.6. Describe the composition of the tail rotor blades.

Aluminum honeycomb covered by stainless steel skin. Stainless steel doublers added at the foot for added strength. Stainless steel leading edge abrasion strips. Root end has an aluminum alloy retention block which houses two spherical bearings to mount the blade to the yoke.

5.3.7. Recognize components of the tail rotor system and their function.

Stainless steel rotor blades, Pitch Change Horns transmit pitch changes to the Blades from the pitch change links, Cross head transmits pitch changes from control tube to the pitch change links, Control tube transmits pitch changes through the gear box to the cross head, Balance Wheel Static Stop, Yoke Assembly.

5.3.8. Described the sequence of events with a tail rotor input.

Right pedal input is transmitted via a push-pull tube to the pitch change mechanism mounted on the tail rotor gearbox. The pitch-change mechanism consists of a Lever, Control Tube, Crosshead, and Pitch Change Links. Right pedal causes the control tube to extend and pushes the crosshead away from the yoke assembly and right pedal decreases pitch……. Left pedal increases pitch.

CHAPTER 6
HYDRAULIC SYSTEM

6.1. State the basic purpose of the TH-57 hydraulic system and identify which control systems receive hydraulic assistance.

Reduces pilot work loads by reducing cyclic and collective control pressures and feedback generated by the main rotor system.

6.2. State the major components of the hydraulic system and their functions.


 * 1. Power Pack: Consists of a 1 pint cooling reservoir, pump, regulating valve (600 ± 50 psi), and a mount for the Nr tach generator. It is driven by the transmission accessory drive-shaft.
 * 2. Filter: Micronic metal filter with No bypass function.  If clogged the red pip pin indicator will pop up.
 * 3. Pressure Switch: Closes and completes the “HYDRAULIC PRESSURE” caution light circuit when the pressure falls bellow 300 psi. The switch opens, turning off the caution light when pressure rises above 400 psi.
 * 4. Solenoid Valve: (Fail Safe Valve): Spring loaded to the on / open position allowing hydraulic fluid to go to the three servos.  Requires 28 vdc to move the valve to the bypass position which direct fluid back to the reservoir instead of going to the servos.
 * 5. Servos: 2 outboard servos are the cyclic servos, middle is the collective.  Used to boost the control inputs.

6.2.1. Identify the components of the power pack and their functions.


 * 1. Reservoir: Finned for cooling, 1 pint capacity
 * 2. Pump Section: Pressurizes hydraulic fluid
 * 3. Pressure Regulator: Regulates hydraulic fluid pressure (600 ± 50 psi)
 * 4. Nr mounting pad

6.2.1.1. State the capacity and pressure requirements of the system.


 * Reservoir Capacity 	1 pint		(MIL-H-83282 or MIL-H-5606)
 * System Capacity	2.25 pints
 * System Pressure	600 ± 50 psi

6.2.2. Identify the components of the filter and their functions.

Head, Micronic Metal Filter Element, Body: A Red warning button on top of the filter pops when filter is clogged. O cockpit indication other than loss of hydraulic system and “Hydraulic Pressure” caution light. There is No bypass Function so when filter clogs the hydraulic system becomes inoperative.

6.2.2.1. State the primary indication of filter stoppage and corrective action.

In flight Indications Procedures If system is restored If system is not restored:
 * 1. HYDRAUIC PRESSURE light
 * 2. Increased force required for control movement
 * 3. Feedback in control
 * 1. Airspeed	Adjust (to obtain most comfortable control movement level)
 * 2. HYDRAULIC BOOST switch	Check ON
 * 3. HYD BOOST circuit breaker	OUT
 * 4. Land as soon as possible
 * 5.	HYD BOOST circuit breaker 	IN
 * 6.	HYDRAULIC BOOST switch	OFF
 * 7.   ©	FORCE TRIM (FT)		ON
 * 8.   ©	AFCS STAB			ON
 * 9.   ©	AFCS ALT			OFF
 * 10. © 	Land as soon as practicable

During Preflight Notify Maintenance

6.2.3. Identify the function of the pressure switch.

Continuously monitors hydraulic system pressure “downstream” from the filter.

6.2.3.1. State how the hydraulic pressure light operates with the pressure switch.

Closes and completes the “HYDRAULIC PRESSURE” caution lithe circuit when the pressure falls bellow 300 psi. The switch opens, turning off the caution light when pressure rises above 400 psi.

6.2.4. Identify the functions of the solenoid.

Spring loaded to the OPEN/on position and allows the hydraulic servos to be bypassed by applying 28 vdc to the solenoid.

6.2.4.1. Describe the operation of the solenoid valve relative to the hydraulic switch.

Switch Position		Solenoid Valve ON	No power to solenoid, spring loaded OPEN position, direct hydraulic fluid to the servos

OFF	28 vdc applied to solenoid which overcomes the spring pressure and moves the valve to the BYPASS position which directs hydraulic fluid to the reservoir instead of going to the servos.

6.2.4.2. State how the hydraulic switch circuit is protected.

5 amp circuit breaker (outboard of igniter CB). If hydraulic boost switch shorts out the hydraulic solenoid will go to the bypass position. To remove the 28 vdc from the solenoid pull the circuit breaker which will restore the hydraulic system.

6.2.5. Name in the three major servo valves and state their functions.


 * Sequence Valve: Traps fluid in servo in case system pressure is lost.  This allows control movement and absorbs rotor system feedback. (Maintains irreversibility)
 * Pilot Valve: Heart of the servo, it takes control inputs (from pilot) and ports fluid to proper side of servo to allow for boosted control inputs.  When the flight control is at the proper position, pilot valve centers and fluid flow stops in the servo.  When system pressure is lost the sequence valve traps fluid in the servo and the pilot valve allows fluid to travel from one side of the servo to the other when flight control inputs are made.  Although the flight control inputs are not boosted because there is no hydraulic pressure, the trapped fluid doe not provide rotor system feedback reduction.
 * Differential Relief Valve: If heavy main rotor loads cause the back pressure to exceed system pressure the differential relief valve will open and allow pressure fluid to be directed to the return line and back to the reservoir.

6.2.5.1. State how a fluid return point is established.

600 ±50 psi hydraulic fluid enters the servo pressure port and is directed to the sequence valve. This pressure pushes down on the popet valve and spring (part of the sequence valve) which opens the return port for fluid to return to the reservoir. If pressure is lost, the spring pops up and closes the return port.

6.2.5.2. Described how the system dampens main rotor feedback.

When system pressure is lost the sequence valve traps fluid in the servo and the pilot valve allows fluid to travel from one side of the servo to the other when flight control inputs are made. Although the flight control inputs are not boosted because there is no hydraulic pressure, the trapped fluid doe not provide rotor system feedback reduction.

6.2.5.3. State the result of excessive system back pressure.

If heavy main rotor loads cause the back pressure to exceed system pressure the differential relief valve will open and allow pressure fluid to be directed to the return line and back to the reservoir.

6.2.5.4. State how flight control receive hydraulic boost.

The pilot valve directs 600 ±50 psi hydraulic fluid to one side of the servo. When the servo moves to the proper position the pilot valve centers and fluid flow is stopped.

6.2.5.5. State how the actuator works when hydraulic pressure is lost.

When system pressure is lost the sequence valve traps fluid in the servo and the pilot valve allows fluid to travel from one side of the servo to the other when flight control inputs are made. Although the flight control inputs are not boosted because there is no hydraulic pressure, the trapped fluid doe not provide rotor system feedback reduction.

CHAPTER 7
ENVIRONMENTAL CONTROL SYSTEM

7.1. Identify the sections of the ventilation and defog systems and state how their associated components work to provide ram air ventilation and defogging.


 * 1. Grill: Keeps FOD out of system
 * 2. Flapper Valve:	Allows outside airflow to enter cockpit, controlled by bent control knob.
 * 3. Axial Blower: Controlled by DEFOG Blower CB type switch located on overhead console.
 * 4. Defroster Nozzle: Directs air from blower to windscreen.
 * 5. Bent Control Knobs: Controls flapper valve, 2 on either side of center console.

Defog works:
 * 1. With both Bent Control Knobs Pulled out all the way.
 * 2. (BEST) Close vent Control Knobs and turn on A/C or heat with defog blower on.

7.2. Identify the major components of the vapor cycle air conditioner and state how they work independently and together to provide cabin air cooling.


 * 1. Switch panel: Contains 2 switches  (Air conditioner On / OFF and fan HI / LOW) and a temperature rheostat.
 * 2. Compressor: Increases pressure of FREON gas.
 * 3. Cools freon gas and changes it from a gas to a liquid.
 * 4. Condenser Blower: Blows air through condenser to cool the freon.
 * 5. Evaporator: Changes freon liquid to a gas thereby absorbing all the heat from the surrounding area.
 * 6. Evaporator Blower: Blows cabin air through evaporator to cool it.

NOTE: System requires about 5 HP to operate.

7.3. Identify the major components of the bleed air heater system in the new B and C, and state how these components warm the cabin air.


 * 1. Heater Silencer: Mixes bleed air and cabin air.
 * 2. Control Valve: Valve overhead pilot’s seat governs the control air.
 * 3. Regulator Valve: Controlled by control air.  Allows bleed air to enter heating system.
 * 4. Evaporator Fan: Circulates the air
 * 5. Duct Temp Switch: Activates Caution light when Temp in duct becomes excessive.

7.3.1. Identify the operational procedures associated with monitoring system temperatures.

When Caution light Illuminates: (Heater Malfunction – Duct too Hot) Procedures: If light extinguishes: If light does not extinguish:
 * 1. CABIN HEAT VALVE		OFF
 * 2. AIR COND/FAN switch		FAN
 * 3. HI/FAN/LO switch			HI
 * 4. Continue flight.
 * 5.	Land as soon as possible

CHAPTER 8
TH-57B ELECTRICAL SYSTEM

8.1. Identify the three sources of electrical power for the TH-57B.


 * Battery
 * Generator
 * External Power Unit

8.1.1. State the power rating of the battery.

24 volt,17 ampere hour

8.1.2. State the generator output.


 * Rated at 30 Volts, 150 amp
 * Regulated to 28 volts, 105 amp

8.1.2.1. State the purpose of the voltage regulator used in the generator system.

Maintains constant generator voltage under varying loads.

8.1.2.2. State the purpose of the overvoltage sensing relay.

Trips the generator reset relay, disconnecting the generator from the circuit, when line voltage reaches 31±1 volts.

8.1.3. State the purpose of the reverse current relay.


 * 1. Connects generator to common BUS only when proper voltage is obtained
 * 2. Prevents current flow from the battery to the generator
 * 3. Disconnects the generator from the common BUS when voltage drops below a safe level

8.1.4. Identify the component that allows the generator to function as a starter.

Starter relay

8.1.4.1. State when the igniters receive power.

When the field control relay is actuated

8.1.5. State the power requirements for an engine start when using external power.

28 vdc 400 amp

8.1.6. Recall the circumstances necessary to illuminate the battery caution lights.


 * 54oC ±3o BATTERY TEMP caution light illuminates
 * 60oC ±3o BATTERY HOT caution light illuminates

8.1.7. State the loadmeter and voltmeter indications that would signify a generator failure.

Load Meter 0 Voltmeter 22 to 24 volts

CHAPTER 9
TH-57C ELECTRICAL SYSTEM

9.1. Identify five sources of dc electrical power for the TH-57C.


 * 1. Main Battery
 * 2. Standby Battery
 * 3. Main Generator
 * 4. Standby Generator
 * 5. External Power Unit

9.2. State the power rating of the standby battery.

22.5 volt. 1.8 ampere hour

9.3. State the purpose of the standby battery.

To supply to 22.5 v power to the pilot’s attitude gyro in the event of a complete loss of power to essential BUS #1.

9.4. State the power rating of the main battery.

24 v, 17 amp hour

9.5. State the purpose of the RCB.

Provides over current protection to the battery (250 amp for 10-20 sec, but will trip with a constant current of 125 amps.)

9.6. State the purpose of the RCB override circuit.

The RCB override is incorporated into the battery and starter switch circuit to prevent the RCB from taking power away from the starter before a complete engine start is accomplished.

9.7. State that main generator output.

28 v, 105 amps

9.8. Described the functions of the voltage regulator used in the main generator system.

Maintains constant generator voltage under varying loads.

9.9. State the purpose of the standby generator.

Provides a backup power source for essential BUS #1 in case the main generator fails.

9.10. State the standby generator output.

28 v 7.5 amps

9.11. State the power requirements for engine start utilizing external power.

28 volt 400 amps

9.12. Describe each function of the voltmeter panel selector switch.

Provides a means to display the voltages at each of the following locations:
 * 1. Main Battery
 * 2. Main Generator
 * 3. STBY Generator
 * 4. STBY Battery
 * 5. ESS 1 BUS
 * 6. ESS 2 BUS
 * 7. NON ESS BUS
 * 8. Flight Control System Inverter

9.13. Describe the alternating current system and identify its power sources.

There are two static inverters (Solid-state) which each take an input of 28 v DC and produce 400 Hz, 115 Volt and 26 v alternating current. The avionics inverter works with the avionics and flight control system yaw axis. The FCS inverter works only with the flight control system. The inverters are controlled by circuit breakers on the overhead console.

CHAPTER 10
THE MINISTAB SYSTEM

10.1. Identify the general characteristics and functions of the MINISTAB system.

A basic three axis system (pitch, roll, and yaw) with force trim designed to provide attitude retention and to smooth pilot input to the controls (rate dampening). It also provides altitude hold in cruise flight (above 40 kts).

10.1.1. Identify the controller buttons and their functions.

STAB:	Engages and disengages the flight control system FT:	Engages and disengages the flight control system ALT:	Engages and disengages the altitude hold mode. TEST:	Initiates a test of the MINISTAB system.

10.1.2. Identify the functions of the force trim and STAB buttons found on the cyclic.

Force Trim: 	When pushed ministab goes in standby and force trim gradient is disengaged. When released Resets ministab and force trim systems. STAB:		Turns ministab on and off.

10.1.3. Describe the functions of the trim damper units.


 * The pitch and roll actuators are located at the top of the control tubes and provides input to the hydraulic servo pilot valves. Therefore they have a low output force.  The pitch and roll computers provide a signal to the actuators which move about a neutral point (0.5 inch total movement NATOPS 2.12.5 pg 2-28, 1.0 total movement Systems Workbook (CNATRA P-402  (rev. 7-98))) to maintain attitude.
 * The yaw actuator is connected to the tail rotor control tube. Since the tail rotor flight controls do NOT have hydraulic boost.  The tail rotor actuator is larger and has a temperature cutoff switch.
 * The Trim Damper Units (TDUs) provide force trim and smoothes / dampens pilot input. Pitch and Roll FT switch is on the cyclic, Yaw FT is on anti-torque pedals

10.2. Identify the major components of the MINISTAB system and state how they function independently and together in the flight control system.


 * Junction box
 * Pitch computer
 * Roll computer
 * Yaw computer
 * Air Data computer

The pitch computer senses changes and makes corrections to maintain the aircraft fuselage in that particular pitch attitude by sending equal signals to both cyclic actuators. Now, to change to a new pitch attitude, all that has to be done is to move the cyclic fore or aft. A micro switch in the pitch TDU senses this longitudinal cyclic movement and activates the pitch computer ICO. Once you stop moving the controls, the computer waits for movement about its axis to stabilize below 1.5o per second for a period of 900 milliseconds. At that time the ICO is secured again. This delay lets the aircraft settle down, and then the computer maintains the new attitude. The roll axis system functions in the same way, except the computer only senses change in the roll axis. For roll inputs the cyclic actuators move simultaneously in opposite directions. To accomplish this, equal signals are sent to both cyclic actuators except one signal is reversed in polarity for roll input, left or right. For the yaw axis, the principal is the same. A rate in the yaw computer senses changes about its axis and makes inputs to the tail rotor controls to hold the last heading set. The yaw system has the micro switches located in the pedal assemblies and not in the TDU. To change heading, move the pedals to the new setting. The micro switch will ICO the computer and once the computer detects that the aircraft has settled down it will maintain the new heading.
 * The junction box interconnects components of the system. Each axis computer contains a rate gyro, memory circuit (integrated rate), and integration cutoff (ICO) circuit. Within each computer, the rate gyro senses movement about its axis, allowing the computer to detect any deviation from the attitude stored in the memory circuit.  The computer then sends a correction signal to the actuator which makes the appropriate control input.  This is how aircraft attitude retention is provided.
 * The air data computer contains transducer that sense airspeed and altitude changes and it also incorporates an airspeed trip switch. The airspeed trip switch tells the FCS when the helicopter is above 40 kts indicated airspeed.  This switch works in conjunction with altitude hold and the yaw axis computer.
 * System Operation

10.3. Identify the operational functions and limitations of the MINISTAB system.

10.3.1. State how movement of the flight the controls operate with the various computers in the MINISTAB system to control flight.

The pitch computer senses changes and makes corrections to maintain the aircraft fuselage in that particular pitch attitude by sending equal signals to both cyclic actuators. Now, to change to a new pitch attitude, all that has to be done is to move the cyclic fore or aft. A micro switch in the pitch TDU senses this longitudinal cyclic movement and activates the pitch computer ICO. Once you stop moving the controls, the computer waits for movement about its axis to stabilize below 1.5o per second for a period of 900 milliseconds. At that time the ICO is secured again. This delay lets the aircraft settle down, and then the computer maintains the new attitude. The roll axis system functions in the same way, except the computer only senses change in the roll axis.

10.3.2. Identify the airspeed and attitude limitations associated with the MINISSTAB system.

With the ministab in operation Vne is reduced to 122 knts at density altitudes of 3000 and below. >3000’ DA will depend on gross weight and DA flown.

=Tyree Systems Gouge=

CH 1 INTRO TO TH-57
Rolls Royce 250C-20J TURBOSHAFT ENGINE MAX TKO GROSS 3200# MAX A/S 130KTS MAX SIDEWARD 25KTS MAX REARWARD 15KTS

MAIN ROTOR DIA 33’4” MAIN ROTOR TO GROUND CLEARANCE 11’7.5”/6’5”

THE AIR FRAME HAS 5 SECTIONS:	FWD/CABIN LANDING GEAR COWLING TAIL BOOM VERTICAL FIN

FWD SECTION

Primarily composed of Al honeycomb covered with an Al or fiberglass skin (excellent strength to weight and aids in soundproofing).

LANDING GEAR

2 AL CROSS TUBES 2 AL SKID TUBES FORMED STEEL TAIL SKID (200# DOWNWARD, 400# UPWARD)

COWLING SECTION

Fwd fairing Al honeycomb with a fiberglass skin, primarily to streamline airflow. Induction fairing is fiberglass, channels air to the engine. Engine cowling is Al (heavily alloyed) permits access to engine and parts. Aft fairing is Al honeycomb w/ a fiberglass skin, and streamlines airflow around the engine oil tank and cooler

TAIL BOOM W/ exception of first 10” is full monocoque Al alloy

VERTICAL FIN Semimonocoque w/ 5.50 offset, helps provide horizontal lift to counteract torque effect.

CARGO HOOK Structural weight capacity of 1500#. Three release mechanisms. 1 electric and 2 manual, one in the cockpit and the other on the hook itself.

Seat restraints activated by deceleration force of 2-3 G’s and caution light panel powered by essential bus #2.

Landing light has a 10min operating limit due to fire hazard.

CH 2 ENGINE
420SHP Bell limited to 317Shp due to pwr train limitations. The four subassemblies are the:	combustion section compressor section accessory gearbox turbine section.

COMPRESSOR ASSEMBLY 4 SUBSECTIONS FRONT SUPPORT COMPRESSOR ROTOR WHEELS AND BLADES CASE ASSEMBLIES DIFFUSER SCROLL

The compressor is 6 stage axial and 1 stage centrifugal. By the time air reaches the diffuser scroll it has been compressed to 6.5 times ambient pressure and has risen to a temp of 500F. The bleed air valve is located on the 5th stage of the compressor at about 2 o’clock.

The combustor is a single can type. Approx. 75% of the air passes around the combustion chamber for cooling the combustion chamber. The rest is mixed with fuel from the fuel nozzle and used for combustion. Once started combustion is self sustaining.

The turbine section is composed of a two stage gas probducer turbine NG or N1and a two stage free power turbine, NF or N2. 2/3 of the energy is used to drive the compressor section and the gas producer drive train. There are 4 thermocouples between the the two sets of turbines, that go to the TOT gauge in the cockpit.

Ng 51,989rpm Nf 33956rpm

The accessory gear box is the primary structural member for the engine. The top pad is used for mounting the anti-icing motor.

Accessories driven by the gas producer: S starter generator T tachometer generator O oil pump F fuel pump F fuel ctrl S stndy gen (C)

Accessories driven by the free turbine: G governor O output shaft T tachometer generator NF T torquemeter

The engine oil system is a pressurized circulating dry sump type oil system. Components:	reservoir Oil pump Internal filter External filter Oil cooler

The res holds 5.5qts and can be checked either by the sight valve or the dipstick with the dipstick being the only way to determine the exact level. It can overflow if the seal in the freewheeling unit fails and transmission oil which lubes the freewheeling unit runs down into the engine oil res. The oil pump is driven by the NG gear train. If the oil filter becomes clogged there is a bypass and the red button will pop out. The filter has a disposable filter element. Coolling air is provided by the squirrel cage fan which is driven by the tail rotor drive shaft that also cools the transmission oil and the hydraulic res. There are two chip detectors in the engine and a temp bulb located tin the oil tank

The fire detection system operates on the pneumatic principle by heat causing expansion in the tube.

Fuel metering is important as improper metering can lead to compressor stalls excessive TOT and rich or lean blowout.

The droop compensation system allows the FCU to anticipate pwr changes based on collective position.

ENG OUT LIGHT 55+-3% ROTOR LOW RPM LIGHT 90+-3%

The FCU is a pneumatic-mechanical type and consist of a gas prodicer FCU unit and the free power governor.

CH 3 FUEL SYSTEM
The fuel cell is a single bladder type and holds 76/91gals. It is crash resistant but not self sealing. Closed circuit pressure refueling is limited to 40 psi.

The fuel boost pumps prevent fuel in line vaporization above 6000ft PA. They are on anytime there is 28Vdc power, and if they fail you must land with 20 gallons of fuel. vice 10 gals normally.

There are 2 float type quantity indicating units in the fuel cell. The fuel pressure transducer is located between the boost pumps and the fuel shutoff valve. In the event off an electrical failure the valve will remain in the last position selected.

The engine fuel pump pressurizes fuel to 650-750psi.

CH 4 POWER TRAIN
The tranny is lubed by a wet sump/pressure lubrication system.

THE OIL PUMP HYDRAULIC PUMP AND THE NR TACH GEN ARE ALL MOUNTED PIGGYBACK ON THE SAME SHAFT.

The barbell shaft has a flexible slpined coupling on each end and allows it some freedon of mumnt with the tranny. The freewheeling unit has an outer race and inner race and a sprag clutch assembley. During shutdown and autos the sprags make minimal contact with the the races.

The tail rotor gearbox has tow fxns. It change the direction by 90 degrees and it reduces the rpms from 6000 to 2554 at 100% NR. The gearbox has a self contained splash type lubrication system with a capacity of 3/8 of a pint.

An extremely hard landing can cause the rivets holding the spike well to shear or the spike may be torn from its mounting. The transmission provides an overall reduction ration of 15.22 to 1.0. The input shaft is rotating at 6000rpm and the rotor mast at 394 rpm.

CH 5 ROTORS AND FLIGHT CTRLS
The main rotor is a two bladed semi rigid, flapping type rotor with an underslung hub. The components are the splined trunion, tension torsion straps, blade grips, pitch change horns, flap restraint assembly, and the main rotor blades. The 2.250 of preconing relieves bending stress of the yoke, blade grips, and the root end of the rotor blade. The tension torsion straps will absorb centrifugal forces and will twist to allow for pitch change action. The latch bolt is used to connect the blade grip and the strap assembly. The vertical through bolt not only secures the rotor blade but is hollow inside to allow for weights for balancing. The rotor blades are of a nonsymmetrical droop snoot design composed of an extended AL alloy nose block, trailing edge, and skin sheets over an Al honeycomb filler.

On the TH-57C the rotor brake has its own hydraulic system, and is mounted on the fwd end of the freewheeling system. The braking action is applied to the main shaft and not the freewheeling unit.

The main rotor blades rotate counterclockwise, and in powered flight the fuselage will attempt to rotate clockwise.

The tail rotor is an anti-torque device and provides motion ctrl around the vertical axis. DYNAMICALLY BALANCED BY THE BALANCE WHEEL AERODYNAMICALLY BALANCED BY THE SPLINED TRUNION AND THE YOKE ASSEMBLY THROUGH OFFSET, NOT UNDERSLINGING THE CYCLIC TILTS THE ROTOR DISK. The stationary swashplate takes ctrl inputs form the cyclic and transmits them to the rotating ctrls. The uniball is what allows the stationary swashplate to tilt in any direction.

The static stop limits tail rotor flapping

LEFT PEDAL INCREASES PITCH, RIGHT DECREASES RIGHT EXTENDS THE CONTROL TUBE  MOVING THE CROSSHEAD WHICH MOVES THE PITCH CHANGE LINKS AND THE PITCH CHANGES

CH 6 HYDRAULICS
The system is made up of the power pack, filter, pressure switch, solenoid valve and servos. There is no bypass in the filter for this system. The pressure light comes on below 300psi and goes back out above 400psi...Normal system charge is 600PSI +/-50

Solenoid Valve Spring loaded to the open position and allows the servos to be bypassed by applying 28Vdc pwr to the solenoid.

Switch pos		Solenoid Valve ON	No pwr to solenoid, spring loaded open position, direct hydraulic fluid to the servos

OFF	28Vdc to solenoid which overcomes the spring pressure and moves the valve to the bypass position which directs hydraulic fluid to the reservoir instead of going to the servos.

The hydraulic switch is protected by a 5A CB. If the boost switch shorts out the solenoid will go to the bypass position. To remove 28VDc from the solenoid pull the CB which will restore the hydraulic system.

There are three major servo valves: Sequence valve-traps fluid in servo in case pressure is lost. This allows ctrl mvmnt and absorbs rotr system feedback.

Pilot valve-takes ctrl inputs and ports fluid to proper side of servo to allow for boosted ctrl inputs. When system pressure is lost the sequence valve traps fluid in the servo and the pilot valve allows it to travel from one side if the servo to the other.

Diferrential relief valve-if heavy main rotor loads cause the back pressure to exceed system pressure the valve will open and allow pressure fluid to be directed to the return line and back to the reservoir.

The force trim system incorporates a dc pwred electromagnetic brake.

CH 7 ECS/ECU
see pub

CH 8 Bravo electrical system
3 power sources: Generator, Battery, External Power (APU)

Battery: 24volts 17Ampere-Hour, Sealed Lead-Acid BATT TEMP Caution Light: 54*C +/-3* BATT HOT Caution Light: 60*C +/-3*

Generator: Rated for 30V 150A, Regulated to 28V 105A. Loadmeter measures % of load on the generator- If reading above 70$ max load, suspect an electrical fire.

The igniter receives power when the field control relay is energized by the starter switch.

The REVERSE CURRENT RELAY (part of generator circuit): Connects generator to common bus only when proper voltage is obtained Prevents current flow from the battery to the generator Disconnects the generator from the common bus when voltage drops below a safe level.

Overvoltage SENSING RELAY trips the generator reset relay, disconnecting the generator from the circuit when line voltage reaches 31 volts.

APU requires 28V 400A

CH 9 Charlie electrical system
5 dc pwr sources, 3 buses, and 115V ac system

5 pwr sources 2 BATTERIES 2 GENERATORS 1 APU

The voltage regulator on the generator provides 28Vddc regulation over and under voltage protection and prevents reverse current flow.

STANDBY BATTERY 22.5V 1.8A, and its only fxn is to provide pwr to attitude gyro in the event of a complete pwr loss to ess bus #1.

The remote ctrl circuit breaker (RCB) provides over current protection to the battery. The override circuit is incorporated into the battery and starter switch to prevent the RCB from taking pwr away from the starter before a comlete engine start is accomplished.

The standby gen is 28V and 7.5A to the essential bus #1. The standby voltage regulator provides undervoltage, overvoltage, short circuit protection, and proper system voltage.

Two inverters, 400Hz 115V and 26Vac.

Avionics inv works with avionics and the FCS yaw axis. The FCS inv works only with the flight ctrl system.

CH 10 MINISTAB
STAB		ENGAGES AND DISENGAGES FCS FT		ENGAGES AND DISENGAGES FT SYSTEM ALT		ENGAGES AND DISENGAGES ALTITUDE HOLD MODE TEST		INITIATES TEST OF MINISTAB

The actuators are high speed motorized jack screws. The yaw system has a larger one as it does not have hydraulics.

The trim damper units (TDU’s) provide force trim and smoothes/dampens pilot input. Pitch and roll FT switch is on the cyclic, yaw FT is on anti-torque pedals.

Integration Cut-off (ICO) occurs when: The pilot moves the cyclic or pedals, in the axis of flight ctrl The pilot depresses the cyclic Ft button in the roll and pitch axis. The FT system is off. Altitude hold is engaged (in the pitch axis only)

Attitude hold is restored: Pilot ceases ctrl input Cyclic FT button released. Mvnmt <1.5 degress per sec. The FT system is on.

Depressing the ALT button engages the air data computer, the airspeed trip switch prevents the ALT fxn from working if A/s is less than 40 kts. The computer uses sttitude to maintain altitude. If computer senses an error greater than 150’ the air data computer will automatically disengage. With the MINISTAB engaged the TH-57’s VNE is reduced to 122kts at DA of 3000’ and below. The light labeled FCS will light for 5 seconds when altitude hold is momentarily turned off or disengaged.

=Study Question Banks=

Hargraves Gouge
TH-57 Systems Ground School Gouge Created September 2005

1, What controls oil flow through the cooler? 2. What are the functions of the tail rotor gearbox? 3. Where is the compressor bleed air valve located? 4. The flap restraint kit is composed of a fly weight and spring assembly (T/F)? 5. When line voltage reaches ___, the generator reset relay will trip? 6. The main rotor is a two-bladed, rigid, flapping type rotor system (T/F)? 7. The tail boom is primarily a _____ structure. 8. How is the trunion mounted to the mast? 9. What section is the primary structural member of the engine? 10. The engine fuel pump pressurizes fuel at ____ psi. 11. If hydraulic pressure is lost, the sequencing valve traps fluid to dampen rotor feedback (T/F)? 12. Fuel pressure gauge reading ___ psi indicates that no boost pumps are operating and flight is restricted to _____. 13. Battery Hot caution light illuminates when battery case temperature reaches 60° C +/- 3° (T/F)? 14. To counter torque, the TH-57 uses ____. 15. Fuel pump and fuel control are driven by the gas producer turbine (Ng) (T/F)? 16. How many and what type turbine wheels are in the turbine section of the 250C-20J engine? 17. The Rolls Royce 250C-20J is rated at 420 SHP and delimited to 317 due to tail rotor limitations (T/F)? 18. The torque gauge continues to flash for ____ seconds to ensure the pilot is aware of over-torque. 19. Damage to the spike or spike well may be an indication of a hard landing (T/F)? 20. The hydraulic solenoid valve is spring loaded to the bypass position and requires electrical power to the solenoid to move the valve to the boosted position (T/F)? 21. The TH-57 transmission case has two magnetic chip detectors which are NOT electrical. (T/F) 22. Depressing the test button on the radar altimeter should ____ 23. The Nf governor has little to no effect on the fuel control system until the twist grip is in the full open position. (T/F) 24. Why is it important to know the exact engine level oil in the TH-57? 25. What component drives the engine oil pump? 26. The actuator arm of the anti-icing motor is in the ___ position when the valve is ______. 27. In the event of an electrical failure, the fuel shutoff valve will remain in the position last selected. (T/F). 28. The hydraulic filter will bypass when pressure drops below 200 +/- 50. (T/F) 29. What are the TH-57 airframe sections? 30. In “flight operational mode,” the TOT gauge will flash ___ per second when 843 degrees centigrade is exceeded. 31. Fuel flows through a ____ at ___ to the gear element of the fuel pump. 32. The gear that drives the transmission oil pump also drives the ____. 33. Two electrical magnetic chip detectors monitor the engine oil for metal particals. (T/F) 34. The DC electrical system of the TH-57B contains a 24V nickel cadmium battery and a second 24v battery used for starts in the winterization kit. (T/F) 35. The GOV RPM switch is used to set a power turbine speed (Nf) between ___ and ___. 36. Which valve traps hydraulic fluid in the servo-acuators with a loss of hydralic pressure? 37. On the A/C control panel, setting the first switch to FAN and the second to HI will____. 38. The droop compensation system is linked to which of the following controls? 39. Dynamic balancing of the tail rotor is accomplished using ____? 40. The free power turbine converts ____ energy to ____ energy. 41. In an autorotation, the sprags of the sprag clutch engage and allow the engine to power the tail rotor drive shaft. (T/F) 42. The gas producer tachometer-generator and the power turbine tachometer are both driven by the gas-producing drive train. (T/F) 43. What are the components of the hydraulic system power pack? 44. Main generator output is regulated at ____ 45. The manual test on the airframe fuel filter will extend upward to indicate filter clogging. (T/F) 46. To ensure high rotational inertia for auto-rotation, weights have been added to vertical through-bolts. (T/F) 47. The DC voltmeter indicates battery or generator voltage. (T/F) 48. The TH-57 horizontal stabilizer is made with a _____ camber and creates a _____, which enables the aircraft to fly at a level attitude at cruise speeds. 49. The tail rotor gearbox has a self-contained pressure type lubrication system. (T/F)
 * Temperature Control Valve
 * 90° angle change and gear reduction
 * 5th stage
 * True
 * 31 volts, +/-1 volt
 * False: semi-rigid vice rigid
 * Full monocoque
 * Spline Mounted
 * Accessory gear box
 * 650-750
 * True
 * 0 PSI…. land ASAP, descend below 6000’ PA
 * True
 * A semi-rigid, flapping type, tail rotor
 * True
 * Four: 2 Ng and 2 Nf
 * False: due to Power Train Limitations
 * 60
 * True.
 * False.
 * False
 * Cause the instrument to indicate 50 +/- 5 and a red flag
 * True
 * To determine overall condition which could indicate a failure at a seal between the freewheeling unit oil system and the engine oil system.
 * Ng gear train
 * forward, closed
 * True
 * False: The hydraulic filter is the only filter with no bypass.
 * Forward section, tail boom section, cowling section and vertical fin section. (actual choices, landing gear not included)
 * Twice
 * low pressure filter, 4 to 30 psi
 * Nr Tachometer generator & Hydraulic pump
 * True
 * False, only the Charlie model has a second battery and it only powers the attitude gyro.
 * between 96 and 101 +/-.5.
 * The Sequencing Valve
 * permit cabin air circulation only.
 * Collective
 * A balance wheel.
 * heat, mechanical
 * False, the sprag clutch provides the means to disconnect the power train from a failed or secured engine.
 * False, The free-power turbine drives four units which can be remembered by the abbreviation GOTT:    G  - Governor (Nf)  O  - Output Shaft (Power)  T - Tachometer-Generator (Nf)  T -  Torquemeter
 * Pressure regulator valve, Nr tachometer mounting pad, pump section, and the reservoir.
 * 28 volts, 105 amperes.
 * False, the manual test button is used to test the fuel filter caution light circuit during preflight.
 * False, To insure high rotational inertia for autorotational flight, weights have been added at the tip and mid-span of each blade.
 * True
 * Negative, download.
 * False, The gearbox has a self-contained splash type lubrication system with an oil capacity of three-eighths of a pint.

Fox Gouge
1. What type of lubrication system is used in the TH-57 main transmission? 2. What is the primary structural member of the engine? 3. Excessive oil quantity in the engine oil reservoir could indicate ____. 4. The hydraulic system reduces pilot workload by reducing control pressures and rotor system feedback. (T/F) 5. The airframe fuel filter is located _____ 6. The root secton of each main rotor has ____ added to increase blade strength. 7. Damage to the spike well may indicate a hard landing. (T/F) 8. The tail rotor is a two bladed semi-rigid flapping type system. (T/F) 9. What are the five accessories driven by the gas producer drivetrain? 10. What, if any, action(s) should you take if a popped hydraulic filter indicator is discovered during preflight? 11. The engine fuel pump pressurizes fuel at ___ psi and passes it to the FCU. 12. The actuator arm of the anti-icing motor is in the ____ position when the valve is ____. 13. Which of the following is/are the purpose(s) of the turbine section of a turboshaft engine? 14. Which of the following actions should be taken if you are operating on one fuel boost pump? 15. The airframe fuel filter test button is used to ___ 16. The tail boom is primarily a ____ structure. 17. When hydraulic system pressure is lost, the ____ valve closes to ____. 18. The diamond J torque gauge digital display will continue to flash for ___ seconds to ensure that the pilot is aware of the over torque.
 * Wet sump, pressure lubrication
 * Accessory gear box
 * Oil transfer from the transmission through the freewheeling unit.
 * True.
 * Right side of the forward firewall.
 * Doublers
 * True
 * True
 * It powers accessories to start and run the engine. STOFF: S -  Starter-Generator  T -  Tachometer-generator  O  - Oil Pump  F - Fuel Control  F - Fuel Pump  S - Standby Generator (C)
 * Report it to maintenance prior to flight.
 * 650 to 750
 * Forward, closed.
 * Convert heat energy to mechanical energy
 * Reduce useable fuel by 10 gallons (for a total of 20 unusable gallons) and avoid maneuvering that would uncover the intake screen and flight is restricted to below 6,000 feet pressure altitude.
 * Test the filter caution light circuit.
 * Full monocoque
 * Sequence…to dampen main rotor feedback.
 * 60

Skinner Gouge
1. Describe the TH-57.
 * The TH-57 is a land based, skid configured, utility type helicopter designed to land on reasonably level firm ground.

2. What is the diameter of the main rotor?
 * 33’-4”

3. What is the turning radius of the TH-57?
 * 22’

4. What powers all light systems?
 * 28vdc common bus

5. What is the operating limit on the landing light?
 * 10 minute limit on landing light, longer periods could cause an overheating condition leading to fire.

6. Identify 5 major section of the airframe.
 * Forward, landing gear, Cowling, tail boom, Vertical Fin

7. What is the construction of the forward section?
 * Aluminum honeycomb covered with fiberglass and aluminum skin, which serves to sound proof the cabin and provide excellent strength to weight ratio.

8. Name the parts of the landing gear.
 * Skid tubes, Cross Tubes, Steel Tail Skid, and 4 Strap Assemblies

9. What absorbs wear on the skids during landing/?
 * Steel Skid Shoes

10. What is the main purpose of the cowling section?
 * To stream-line air flow around engine and transmission.

11. Describe the construction of the tail boom.
 * Full monocoque construction with a covering of aluminum alloy, except for the first ten inches.

12. What is the purpose of the tail boom?
 * It provides an extended mounting point for the tail rotor and to increase the moment arm.

13. What is the function of the horizontal stabilizer?
 * Its negative camber provides a download that enables the aircraft to fly at near level during cruise.

14. What is the purpose of the vertical fin?
 * It provides directional stability and reduces tail rotor loads in forward flight using a 5.5o offset.

15. What is the structural weight capacity of the cargo hook?
 * 1500 lbs

16. How many release mechanisms does the cargo hook have?
 * 3, two mechanical and one electrical

17. Name the components of the cowling section.
 * Forward, Induction, Engine, and Aft fairing

18. Name the engine used in the TH-57
 * Rolls Royce 250C-20J Turboshaft

19. What is the power output of the engine?
 * 420 SHP rated, derated to 317 SHP by Bell Helicopter due to transmission limitations.

20. Name the four sub-assemblies of the engine.
 * Compressor, Combustion, Turbine, and Accessory gear box

21. Name the four components of the compressor section.
 * Front Support, Rotor wheels and blades, case assembly, and diffuser scroll

22. Describe the location and purpose of the anti-icing valve.
 * The anti-icing valve is located on top of the diffuser scroll, and when opened provides 500of air to the front support.

23. What type of compressor is used in the engine?
 * A six stage axial, single stage centrifugal compressor is used to provide 6.5 times the ambient pressure compression.

24. Describe the function of the rotors and stators in the compressor section.
 * Rotors increase the velocity of the air while the stators decrease velocity to increase static pressure while directing the air to the next stage.

25. Describe the location and function of the compressor bleed valve.
 * The valve is located at the fifth stage of compression and it regulates pressure to prevent stall.

26. What type of combustor is used in the Rolls Royce 250C-20J?
 * A single can type

27. Describe the location and function of the burner drain valve.
 * It is located at the lowest point on the combustion chamber and serves to eliminate accumulations of fuel.

28. What is the compression ratio and temperature of the air upon arrival at the diffuser scroll.
 * 6.5:1 Compression and 500of

29. State the location and function of the fuel nozzle and ignitor plug.
 * They are both located at the aft end of the burner-can. The fuel nozzle introduces fuel to the can while the ignitor plug initiates combustion (During start only).

30. Describe the function of the air entering the combustion section.
 * 75% of the air entering the combustion section passes around the combustor liner for cooling the remaining 25% of the air is used for combustion.

31. What is the purpose of the four stage turbine?
 * Converts the heat energy provided by the combustion process to mechanical energy.

32. What portion of energy is used to drive the compressor section and gas producer drive train?
 * Approximately 2/3’s

33. What type of connection exists between the gas producer and free-power turbine?
 * A gas coupling exists. There is no mechanical connection between the Ng and Nf.

34. How is TOT measured?
 * Hot gases pass over the 4 thermocouples located at the exhaust end of the Ng turbine. The 4 signals are averaged and sent to the TOT gauge located on instrument panel.

35. What is the purpose of the accessory gear box?
 * It is the primary structural member for the engine and provides mounting for the compressor and turbine assemblies.

36. What engine accessories are powered by the gas producer section?
 * Starter generator
 * Tach generator (Ng)
 * Oil pump
 * Fuel pump
 * Fuel control unit

37. What engine accessories are driven by the free power drive train?
 * Governor Nf
 * Output shaft
 * Tach Generator
 * Torque meter

38. What type of engine oil system is used?
 * Dry sump, pressurized, circulating oil system

39. What is the capacity of the oil system?
 * 5.5 quarts

40. Describe the location and type of engine oil pump.
 * The oil pump is located in the accessory gear box, and is a gear type consisting of one pressure element and four scavenge elements.

41. What happens if the oil filter becomes clogged? 42. How is the engine oil cooled?
 * A bypass will allow the oil to return to the oil tank and the pressure will pop a red indicator button out.
 * After the oil has been filtered it is routed to a radiator type cooler near the oil tank. Cooling air is provided by a squirrel cage fan driven by the tail rotor drive shaft.  This air also cools the transmission oil and the hydraulic fluid.

43. How is the engine oil temperature transmitted to the cockpit?
 * A temperature bulb, located in the oil tank, sends an electrical signal to the cockpit gauge.

44. Describe the engine oil system chip detectors.
 * The chip detectors monitor engine oil for metal particles. They incorporate an electro-mechanical system to distinguish normal wear from more serious damage.

45. What type of FCU is used in the engine?
 * A pneumatic-mechanical type

46. What is the purpose of the idle detent?
 * To prevent the twist from being rotated direct to the closed position.

47. How does the Nf governor work?
 * The Nf governor senses the power required to maintain 100% Nf RPM and adjusts the gas-producer RPM accordingly.

48. What is the purpose of the droop compensator?
 * To minimize transient RPM variations as power changes are made.

49. What is the function of the linear actuator?
 * Allows the pilot to adjust the Nf turbine RPM through the use of the beeper control on the pilot’s collective.

50. Where is the anti-icing motor located?
 * On the top mounting pad of the accessory gear box.

51. What is the twist grip control linked to?
 * It is linked to the gas producer fuel control unit.

52. How is the power turbine governor controlled?
 * Through a linear actuator and droop-compensating system.

53. How is a free-wheeling unit oil seal failure recognized?
 * By an overflow of engine oil and a transmission oil decrease.

54. Where is the oil tank mounted?
 * Over the tail rotor drive shaft on the aft deck of the fuselage.

55. What does the first nozzle assembly do to the expanding gasses?
 * It accelerates the gasses and then directs them to the turbine wheel.

56. State the purpose of the splined trunnion.
 * It provides a mounting point for the yoke assembly and a flapping axis for the main rotor.

57. How is the yoke mounted to the splined trunnion?
 * By pillow blocks which have centering provisions for the yoke.

58. State the amount and purpose of preconing?
 * 2-1/4o, relives bending stress of the yoke, blade grips, and blade root.

59. State the purpose of the tension-torsion strap?
 * To hold the blade grip to the yoke assembly, to absorb centrifugal forces, and to allow pitch change action.

60. State the purpose of the latch bolt.
 * Connects the blade grip and the tension torsion strap

61. How is the rotor blade mounted to the blade grip?
 * By a hollow vertical through bolt that allows balance weights to be installed.

62. How is high rotational inertia achieved on the rotor blades?
 * During blade construction internal weights were added t the tip and the mid-span of each blade to balance each precisely.

63. State the purpose of the flap restraint kit.
 * To prevent excessive blade flapping during low rotor PRM (Below 25%-32% Nr)

64. Describe the main rotor system.
 * It is a two bladed, semi-rigid, flapping type rotor system with an underslung hub.

65. State the purpose of underslinging.
 * To keep the rotor system balanced during flapping or tilting (i.e. Corrects for geometric imbalance)

66. Describe the tail-rotor assembly.
 * Two bladed, semi-rigid, flapping type system, with the all metal blades having a diameter of 5’-5”.

67. State the purpose of the tail-rotor.
 * To counteract the torque effects of the main rotor system.

68. What provides dynamic balancing of the tail rotor?
 * Weights located on the balance wheel.

69. What limits the amount of flapping by the tail rotor?
 * Static stops located next to the balancing wheel.

70. How is aerodynamic balance accomplished in the tail rotor?
 * By establishing an offset between the splined trunnion and the yoke.

71. State the purpose of the cyclic control.
 * To tilt the rotor disc in the desired direction of turn. This is done by changing pitch equally in both blades but in opposite directions.

72. State the purpose of the collective.
 * To change the pitch of both blades simultaneously and equally in the same direction.

73. State the purpose of the swashplate.
 * To take control inputs from the cyclic and transmit them to the rotating controls.

74. State the purpose of the uniball.
 * It allows the stationary swashplate to tilt in any direction.

75. Describe the related tail rotor pitch changes to pedal movements.
 * Left pedal increases pitch, right pedal decreases pitch.

76. What type of boost aids pilot cyclic and collective inputs?
 * Hydraulic boost

77. How much does a single main rotor blade weigh?
 * 94 lbs

78. What type of assembly is the flap restraint kit?
 * Fly weight and spring type system.

79. In powered flight, what direction does the fuselage attempt to rotate?
 * Right

80. State the function of the isolation mount.
 * To align the transmission and isolate vibrations.

81. Describe the effects of a hard landing on the spike well area.
 * A hard landing will cause the rivets holding the spike well to shear or the spike may be torn from its mount.

82. What is the overall gear reduction and resulting RPM of the main transmission?
 * Two stage reduction resulting in a 15.22:1 overall reduction. Input shaft 6000 RPM Main rotor turns at 394 RPM (100% Nr)

83. Identify the type of lube system used in the main transmission.
 * Wet sump pressure lubrication

84. State the location and capacity of the wet sump.
 * Located in the lower case of the transmission and it holds five quarts.

85. Where is the transmission oil pump, and what drives it?
 * The pump is internally mounted in the lower transmission case and is driven by the accessory gear drive which also drives the hydraulic pump and Nr tach generator.

86. At what temperature will the TRANS OIL TEMP caution light come illuminate?
 * 110oC

87. Describe the sprag clutch assembly.
 * The sprag clutch assembly is the main component of the freewheeling unit and provides a means to disconnect the power train form the engine.

88. What are the two purposes of the tail rotor gear box?
 * It changes direction of the drive by 90o, and provides a gear reduction to turn the tail rotor at approx. 2554 rpm

89. What type of lubrication does the tail rotor gear box use?
 * A self-contained splash type system.

90. When does the TRANS OIL PRESS caution light illuminate?
 * When transmission oil pressure falls below 30±2 psi.

91. What is the purpose of the transmission oil cooler?
 * To regulate the oil temp before it flows to the transmission and freewheeling unit.

92. Does the freewheeling chip detector have a chip light?
 * The transmission chip light will illuminate as they use the same lubrication system.

93. If the barbell shaft fails, what will drive the tail rotor?
 * The engine

94. What transmits power from the power output shaft to the barbell shaft?
 * Freewheeling unit

95. What system lubricates the freewheeling unit?
 * The transmission lubrication system

96. Where is the engine oil pump located?
 * In the accessory gear box

97. What are the five parts of the hydraulic system?
 * Power Pack, filter, low pressure switch, solenoid valve, servos

98. What does the hydraulic system do?
 * It reduces pilot workload by reducing control pressures and feedback generated by the main rotor system.

99. What is the capacity of the hydraulic reservoir.
 * 1 pint

100. What is the hydraulic system pressure?
 * 600±50 psi

101. What is the indication of a clogged hydraulic filter?
 * A popped filter indicator means filter stoppage and should be replaced because no bypass exists for the hydraulic filter.

102. What does the hydraulic pressure switch do?
 * It monitors system pressure and closes when pressure falls below 300 psi and illuminates the caution light. The switch will then reopen when system pressure rises above 400 psi.

103. If pressure is lost in the hydraulic system, what does the sequence valve do?
 * The sequence valve closes, trapping fluid in the servo which will continue to dampen main rotor feedback.

104. What controls are hydraulically assisted?
 * Cyclic and Collective

105. What allows hydraulic fluid to move from one side of the actuator to the other?
 * The pilot valve

106. What terminates hydraulic boost to the flight controls?
 * Turning the hydraulic system switch off

107. Describe the fuel cell?
 * The fuel cell is a single bladder type that is crash resistant, but not self sealing. It holds 91 gallons in the Charlie and New Bravo and 76 gallons in the Old Bravo (161xxx).  The system may be gravity or pressure refueled.

108. What is the max close-circuit refueling pressure?
 * 40 psi per NATOPS

109. What do the electrical boost pumps do?
 * They provide pressurized fuel to the engine driven boost pump preventing inline vaporization above 6000’ PA.

110. When does the FUEL PUMP caution light illuminate?
 * When discharge pressure falls to 3.5 psi.

111. What are you restricted to with a boost pump failure?
 * Flight is restricted to below 6000 ft and useable fuel is reduced by 10 gallons. Care should be given to avoid maneuvers that might uncover the intake screen.

112. How is fuel quantity measured?
 * By two float type quantity indicating units located in the cell. Both units provide inputs to a single indicator in the cockpit.

113. When does the FUEL LOW caution light illuminate?
 * 20 gallons

114. State the location and function of the fuel pressure transducer.
 * The fuel pressure transducer is located in the fuel line between the boost pumps and the fuel shutoff valve. It sends a signal to the fuel pressure gauge in the cockpit.

115. In the event of an electrical failure, what happens to the fuel shut-off valve?
 * Remains in its last position selected before the failure.

116. What pressure does the fuel leave the engine driven fuel pump?
 * 650-750 psi

117. What causes the A/F FUEL FILTER caution light to illuminate?
 * If a differential pressure is felt across the filter. This indicates impending failure and triggers the caution light to illuminate.

118. How much horsepower is required to operate the air conditioning system?
 * 5 hp – Vapor cycle (freon)

119. What controls the amount of ventilating air entering the cabin?
 * Two push pull cables either side of the center console.

120. What is the air conditioning compressor belt connected to?
 * The tail rotor drive shaft.

121. The defog system works best in conjunction with what?
 * Bleed air heater or Air conditioner

122. The regulator valve determines what?
 * How much bleed air is mixed with cabin air in the heater silencer.

123. What are the sources of electrical power for the TH-57B?
 * Main Battery, Generator, External Power Unit

124. What is the power rating of the battery?
 * 24 v, 17 amp hour

125. What is the power rating of the generator?
 * 30 v 150 amp regulated to 28 v 105 amp

126. What type of voltage regulator is used in the Bravo?
 * A carbon pile type

127. At what voltage will the generator go off line?*
 * 31±1 vdc the overvoltage sensing relay trips the generator reset relay which drops the generator off line.

128. What are the functions of the reverse current relay?
 * It prevents current flow from the battery to the generator, and connects the generator to the common bus only when proper voltage is obtained. It will disconnect the generator when the voltage drops below a safe level.

129. What is the power rating required for the external power unit?*
 * 28 v 400 amp

130. What component allows the generator to function as a starter?
 * The generator field relay

131. What is the minimum acceptable voltage for a battery start?
 * 24 vdc

132. When does the BATTERY TEMP caution light illuminate?
 * 54±3oc battery case temp

133. When does the BATTERY HOT caution light illuminate?
 * 60±3oc battery case temp

134. What loadmeter and voltmeter indications would signify a generator failure?
 * Voltmeter – 24 v
 * Loadmeter – 0%

135. What are the five sources of DC power for the TH-57C?


 * Main Battery
 * Standby Battery
 * Main Generator
 * Standby Generator
 * External Power unit

136. What is the power rating and function of the standby battery?
 * 22.5v and 1.8 amp hours, its only purpose is to provide power the pilot’s attitude gyro in the event of a main battery and main generator failure.

137. What is the purpose of the remote circuit breaker?
 * To trip and drop the main battery off line (by popping the Battery relay) in the event constant line current exceeds 125 amps.

138. What is the purpose of the battery protection system?
 * To prevent the RCB from taking power away from the starter before a complete engine start is accomplished.

139. What type of voltage regulator does the TH-57C use?
 * A solid state type voltage regulator

140. What is the purpose of the voltage regulator?
 * To protect the system from both over and under voltage conditions, to prevent reverse current flow and to control the resistance of the generator field in order to regulate voltage output.

141. What is the purpose of the standby generator?
 * The 28 vdc 7.5 amp generator supplies power to the Essential Bus #1 in the event of a main generator failure.

142. What is the output of the inverters?
 * 400 Hz 115 vac and 26 vac

143. What is the function of each inverter?
 * Inverter #1 (Avionics Inverter) – Supplies AC power to Avionics and the Yaw axis of the flight control system.
 * Inverter #2 (FCS Inverter) – Supplies AC voltage to the Pitch and Roll axis of the Flight Control System.

144. Which Ministab systems have hydraulic assist?
 * Pitch and roll

145. When will ICO (Integrated Cut Out) occur?
 * When the pilot moves the flight controls, when force trim is disengaged, or when altitude hold (pitch axis) is on.

146. Depressing the ALT button engages which computer?
 * Air Data computer

147. At what airspeed will the altitude hold function disengage?
 * When airspeed falls below 40 kts.

148. When will the air data computer automatically disengage?
 * When the computer senses an altitude error of greater than 150 ft.

149. After movement, when will the ICO re-engage?
 * When movement stabilizes below 1.5o per second for 900 milliseconds

150. What is the airspeed limitation when the ministab is in operation?
 * Vne is limited to 122 knts at DA of 3000 ft and below

151. What are the major components of the ministab system?
 * Pitch computer, roll computer, Yaw computer, air data computer and junction box

152. A lateral control movement with the stab button on causes ICO in which axis?
 * Roll axis

153. At what pressure is hydraulic fluid supplied to the rotor brake system?
 * 100-120 psi

154. When should the rotor brake system be engaged?
 * Between 38%-30%

155. Where is the direct reading pressure gage associated with the rotor brake?
 * Overhead between the two pilots

156. What are the three wet-line gages in the cockpit.
 * Engine torque has a wet line to a transducer which then sends an electrical signal to the gauge.
 * Engine Oil Pressure
 * Transmission Oil Pressure

Italian Gouge
1. The 250C-20J engine in 420 shp derated to 317 from the Bell Industry due to Tail Rotor limitation. (T/F) 2. The Rolls Royce 250C-20J is derated to ____ 3. Max capacity of cargo hook ____ 4. Length of “Drooped Blade” in the back ___ 5. What are the different sections of the airframe? 6. What are the different sections of the engine? 7. What are the different sections of the compressor section? 8. Where are the “airfoil-shaped stationary blades” (in the six-stage axial compressor mounted? 9. Where is the bleed air valve mounted? 10. Where are the fuel nozzle and igniter plug? 11. Where is the “compressor discharge air transfer tube” located? 12. The squirrel cage type fan is driven by ____ 13. The only way to detect the exact oil level is ___ 14. Which oil system lubricates the freewheeling unit? 15. In flight operational mode TOT flashes twice per seconded above 843°C. (T/F) 16 For how many seconds will the digital display of the torque gauge flash? 17. In what position must the Anti-Icing switch be during preflight inspection? 18. What is the rang eof the governor RPM (Beep Control)? 19. What does the TOT light do when TOT is over 843°C? 20. What are the lower limits of the twist grip for flight idle? 21. In order to read TOT you nead 28v DC. (T/F) 22. Two chip detectors are electric in the engine. (T/F) 23. Both Transmission Chip lights are not electrical. (T/F) 24. What happens when you press the manual test button on the Airframe fule filter. 25. What power does the Fuel Boost Pump require? 26. What is the max refueling pressure? 27. What is the operating pressure of the Engine Drive Fuel Pump? 28. When does the Low Fuel light come on? 29. What causes the Trans Oil Press light to come on? 30. A solid state voltage is regulator on the TH-57B. 31. What other elements are splined to the accessory gear drives? 32. Where is the Barbell shaft located? 33. During autorotation the Sprag Clutch remains engaged. (T/F) 34. What part of the Freewhelling unit remains connected during Autorotation? 35. Is the freewheeling unit chip detector electrical? 36. What are the functions of the Isolation Mount? 37. What precaution has been built into the yoke to diminish bending stress? 38. Is the tail rotor a semi-rigid, flapping type system? 39. What limits the “flapping of the Tail Rotor? 40. Does the right pedal raise or decrease the pitch? 41. When you pull the collective what happens to the swashplate? 42. What are the servo actuator components? 43. Which valve traps/maintains oil inside the actuator when you loose hydraulic pressure? 44. How do you turn off the hydraulics? 45. How do you check the hydraulic oil level? 46. Hydraulic filter is not bypassing at 300 +/- 50 psi 47. What does the Force Trim provide? 48. The defog system works best in conjunction with 49. What monitors the temperature on the outlet side of the heater silencer? 50. What type of battery is in the TH-57B? 51. What temperature range activates the “BAT HOT” temp light? 52. What are the functions of the Reverse Current Relay? 53. When does the generator work as a starter? 54. What is the composition of the tail rotor blades? 55. What are the voltage and amperage requirements to use an EPU for start? 56. What are the cockpit indications of Main genrator failure? 57. The airframe fuel filter manual test pops out when clogged. (T/F) 58. The two chip detectors in the main transmission case are not electric. (T/F) 59. The engine oil temperature bulb is on the oil tank. (T/F) 60. What are the components of the Tail Rotor? 61. A fuel pressure gauge reading ____ indicates both pumps hve failed, so flight is restricted to ________ 62. The primary purpose of the tail boom is _____ 63. During autorotation the spags of the Sprag Clutch engage so that the engine powers the tail rotor. (T/F) 64. The airframe fuel filter is located on the right side of the forward firewall. (T/F) 65. The boost pumps send fuel to the Engine Driven Fuel Pump at 4-30psi. (T/F) 66. Vent air is regulated by a push pull knob. (T/F) 67. How is temperature sensed on the heater silencer? 68. If the “Duct Hi Temp” light illuminates____ 69 By turning on the Anti-Ice switch you activate an electronic motor mounted _____ 70. The engine oil system is a _______ used to lubricate and cool engine bearings. 71. By raising the collective, you raise the swashplates and ______ blade pitch equally. 72. How is the Trunion mounted on the mast? 73. The Trans Oil Press light comes on when pressure exceeds 70 psi (T/F) 74. What controls oil flow to the oil cooler. 75. The flap restraint is a flyweight and spring type. (T/F) 76. Setting the A/C panels switches to “FAN” and “HI we permit cabin air circulation only. (T/F) 77. What increases main rotor blade strength? 78. The tail rotor is ____ type. 79. Excessive oil quantity in the engine oil reservoir is due to_____. 80. What is the function of the uniball. 81. What provides cooling air for the engine oil system? 82. The flap restraint kit is ___ part of the Rotor System. 83. What do GOTT and STOFF stand for? 84. If the button of the hydraulic filter is popped during the preflight ____ 85. The anti-ice system is closed when the anti-0ice actuator rod ____ 86. The tail boom is a _______ construction. 87. What is the function of the sequence valve in the event of pressure loss? 88. What are the components of the Power Pack? 89. What are the locations of Fuel Nozzle and Igniter? 90. Fuel prior to reaching the engine driven pump passes through the low pressure filter at is at ___ 91. The combustion chamber is _____ 92. If fuel metering is incorrect for the velocity and pressure of the air through the engine, the following problems can  occur: 93. Ram air enters the cabin by ____ 94.The major components of the Main Rotor Blades are _____ 95. Which control is connected to the droop compensating system? 96. What is the primary structure of the engine section? 97. Damage of the spike indicates _____ 98. Where are the air transfer tubes located? 99. Name the inputs to the FCU:
 * False, due to transmission power train
 * 317 shp
 * 1500 lbs
 * 1’1.5’’ (6’5’’ in front)
 * Forward/Cabin, Landing Gear, Cowling, Tail boom, Vertical fin (5 parts)
 * compressor, accessory gearbox, turbine, combustion (4 parts)
 * front support, compressor rotor wheels & blades, case assemblies, diffuser scroll (4 parts)
 * Mounted to the compressor case “stators”
 * 5th stage of the compressor
 * At the aft end of the combustion section
 * Between the diffuser scroll and combustion section
 * Tail rotor drive shaft system
 * With the dipstick (on the Right side)
 * Transmission Oil system
 * True
 * 60
 * Closed, with the rod in the forward poison in the engine compartment.
 * 96-101% +/-0.5%
 * It will flash twice per second.
 * 59-65% (per new NATOPS changes)
 * True
 * False, they are electromagnetic. (WARNING THIS ANSWER IS DISPUTED)
 * NATOPS refers to the trans chip detectors as "electrical" and the systems book refers to them as "electro-magnetic." Either would work and there probably isn't a question that gives you both as answers. As long as you understand that they are NOT simply magnetic and they do infact use electricity.
 * False, they are electrical
 * You test the Fuel Filter caution Light circuit.
 * 28 volt DC.
 * 40 psi
 * 650-750psi
 * 20 gallons remaining
 * 30 +/-2 psi
 * False on the “C” version.
 * Nr Tach Generator and the Hydraulic Pump
 * Between the transmission and the freewheling unit.
 * False
 * The outer portion.
 * Yes. (the new electo-magnetic ones have replaced the old magnet only detectors in the freewheeling unit)
 * To align the transmission and isolate vibrations.
 * 2 1/4° preconing
 * Yes
 * The static stop
 * Decrease
 * It rises.
 * Sequence Valve, Pilot Valve, Differential relief Valve
 * Sequence Valve
 * Move the Hydraulic Boost Switch to the off position (requires electrical power to move solenoid valve)
 * Sight gage.
 * False, hydraulic filter never bypasses but caution light comes on at 300psi and off at 400
 * Artificial feel, and trim for the cyclic
 * Air conditioner or heater system
 * Duct Temperature Switch
 * A nickel-cadmium battery
 * 60+/-3°C
 * Connects generator to common BUS only when proper voltage is obtained, Prevents current flow from the battery to the generator, Disconnects the generator from the common BUS when voltage drops below a safe level.
 * When the starter relay is actuated/energized
 * The blades are all metal constructed of aluminum honeycomb, covered by a stainless steel skin. Stainless steel doublers have been added at the root end and a stainless steel abrasion strip has also been added to the leading edge.
 * 28volts 400 amps
 * Loadmeter 0 and 22-24volts on the voltmeter
 * False
 * False
 * True
 * Rotor blades, Pitch change horns, crosshead, control tube, balance wheel, static stop and yoke assembly.
 * 0, below 6000’
 * To extend a support on which to mount the Tail Rotor
 * False, the sprag clutch disengages from the engine during autorotation
 * True.
 * True
 * True
 * Duct Temperature Switch.
 * ECS to “FAN” position, Fan speed to “HI” position, Cabin Heat valve “OFF”
 * at the top of the accessory gear box.
 * Pressurized, circulating, dry sump type
 * Increase
 * It is spline mounted.
 * False, it comes on when pressure drops below 30+/-2psi
 * Temperature Control Valve
 * True
 * True
 * Doublers
 * Duel bladed, semi-rigid, flapping type
 * Failure of a seal allowing transmission oil to enter the oil system.
 * It allows the stationary swashplate to tilt in any direction.
 * Squirrel cage fan, driven by the tail rotor drive shaft
 * not
 * G - Governor (Nf)  O  - Output Shaft (Power)  T - Tachometer-Generator (Nf)  T -  Torquemeter
 * S - Starter-Generator  T -  Tachometer-generator  O  - Oil Pump  F - Fuel Control  F - Fuel Pump
 * Report it to maintenance prior to flight.
 * is in the forward position.
 * Full monocoque
 * Trap fluid in the servo which will continue to dampen main rotor feedback
 * Reservoir, Pump Section, Pressure Regulator, Valve, Rotor Tachometer Generator
 * Aft end of combustion section
 * 4-30psi
 * Single Can
 * Excessive temperature, compressor stall, compressor surge, rich or lean blowout.
 * Two push pull cable controls located on either side of the center console.
 * Splined Trunion, Yoke, Torsion Tension Straps, Blade Grips, Pitch Change Horns, Flap Restraint kit, Main Rotor Blades.
 * Collective
 * Accessory Gearbox
 * A hard landing.
 * Between the diffuser scroll and the combustion chamber.
 * (I do not remember the options, so review this subject)