Aero Test

=TH-57 AERODYNAMICS ENABLING OBJECTIVES=

CHAPTER ONE:
1.1	RECALL THE MAIN GASES OF THE AIR.
 * 78% Nitrogen, 21 %Oxygen, 1% Other Gases
 * Note: At 100% relative humidity, water vapor is only 4% by volume.

1.2	RECALL THE EFFECT OF PRESSURE, TEMPERATURE, AND HUMIDITY ON THE DENSITY OF THE AIR.
 * Recall Density is Mass per unit Volume ... Density = Mass/Volume.
 * As PRESSURE INCREASES, DENSITY INCREASES (air molecules are forced closer together, therefore more molecules per unit volume.
 * As TEMPERATURE INCREASES, DENSITY DECREASES (air molecules are moving faster and therefore taking up more room resulting in fewer molecules per unit volume).
 * As HUMIDITY INCREASES, DENSITY DECREASES (water molecules are lighter than air molecules, therefore less dense).
 * NOTE: Pressure & Temperature have greatest effect on density.

1.3	DEFINE PRESSURE ALTITUDE.
 * The altitude of a given atmospheric pressure in the standard atmosphere, i.e., the altitude in reference to the standard datum plane, 29.92" Hg., 150C. Adiabatic Lapse Rate -20/1000'

1.4	DEFINE DENSITY ALTITUDE.
 * Density altitude is pressure altitude corrected for temperature and humidity (the altitude in the standard atmosphere corresponding to a particular value of air density).

1.4.1	RECALL THE EFFECT OF TEMPERATURE AND HUMIDITY ON DENSITY ALTITUDE.
 * As temperature increases, density altitude increases. As relative humidity increases, density altitude increases. For every 10% increase in R.H., D.A. Increases by 100 feet.

1.4.2	COMPUTE THE DENSITY ALTITUDE UTILIZING A DENSITY ALTITUDE CHART.
 * See Chart at right

1.4.3	COMPUTE THE DENSITY ALTITUDE UTILIZING THE RULE OF THUMB FORMULA.
 * Density Altitude = P.A. + [ OAT @ Alt (C) - Standard Temp @ Alt] X 120 + (R.H./10%) X 100

1.4.4	RECALL THE RELATIONSHIP BETWEEN HELICOPTER PERFORMANCE & DENSITY ALTITUDE
 * As DENSITY ALTITUDE INCREASES, ENGINE POWER AVAILABLE DECREASES (less dense air means less mass which results in poorer engine performance (F=M*A)).
 * As DENSITY ALTITUDE INCREASES, POWER REQUIRED INCREASES (less dense air requires high AOA to get the same amount of lift, the higher AOA increases drag which requires more power).
 * NOTE: Power required is the amount of power needed to turn the rotor at a constant speed (Nr). As DA increases, the pitch angle of the rotor blades must increase to generate the same amount of lift, this creates more drag forces on the rotor system and therefore more power is required to maintain a constant Nr.

CHAPTER TWO
2.1	DRAW A BLADE ELEMENT DIAGRAM. 2.1.1	DEFINE: AIRFOIL, CHORDLINE, TIP-PATH PLANE, AERODYNAMIC CENTER, ROTOR DISC, PITCH ANGLE, LINEAR FLOW, INDUCED FLOW, ANGLE-OF-ATTACK (AOA), LIFT, INDUCED DRAG, PROFILE DRAG, THRUST, IN-PLANE DRAG.
 * See image at right.
 * Remember that the Velocities have two names
 * Resultant Velocity is Relative Wind
 * Rotational Velocity is Linear Flow
 * Induced Velocity is Induced Flow
 * AIRFOIL: A structure designed to produce lift as it moves through the air


 * CHORD: The distance between the leading and trailing edges along the chordline


 * CHORDLINE: A straight line intersecting the leading and trailing edges of an airfoil


 * TIP-PATH PLANE: The path described by the tips of the Main Rotor Blades as they rotate


 * AERODYNAMIC CENTER: Point along the chordline where all changes in lift are considered to take place


 * CENTER OF PRESSURE: Point along chordline at which all aerodynamic forces (distributed lift, upper and lower surface) are acting


 * ROTOR DISC: Area of the circle inscribed in the tip-path-plane


 * PITCH ANGLE: Angle between the CHORD LINE and the TIP-PATH-PLANE


 * LINEAR FLOW:- HORIZONTAL flow of air, opposite the direction of the airfoil


 * ROTATIONAL FLOW: Linear flow for rotating airfoils (rotor blade)


 * INDUCED FLOW: DOWNWARD (VERTICAL) flow of air through the rotor (i.e., Rotor-Wash)


 * ANGLE-OF-ATTACK (AOA): Angle between the RELATIVE WIND and the CHORD LINE


 * LIFT: The component of the total aerodynamic force (thrust) which is perpendicular to the relative wind


 * INDUCED DRAG: The horizontal component of lift (parallel to the tip-path-plane) which tilts the lift vector aft; caused by induced flow and trailing vortices


 * PROFILE DRAG: Result of air friction acting on the blade element. (parallel to the relative wind) NOTE: In a hover profile drag accounts for 25% of the total power, 75% of the power is induced power


 * THRUST: Rotor thrust is the total aerodynamic force produced in the rotor system used to overcome the weight of the helo.


 * IN-PLANE DRAG: The summation of all decelerating forces in the plane of rotation (Induced Drag + Horizontal Component of Profile Drag)

2.1.2	STATE THE RELATIONSHIPS BETWEEN INDUCED FLOW, LINEAR FLOW, AND RELATIVE WIND; BETWEEN RELATIVE WIND AND ANGLE-OF-ATTACK; BETWEEN PITCH ANGLE AND ANGLE-OF-ATTACK.


 * RELATIVE WIND is the vectorial resultant of LINEAR FLOW + INDUCED FLOW. Increasing induced flow shifts the relative wind toward the chord line (more vertical), thereby reducing AOA. Increasing the linear flow will shift the relative wind away from the chord line (more toward the horizontal) and thereby increase the AOA. Pitch angle directly affects AOA. (As pitch angle increases, AOA increases, which increases LIFT).

In Summary: LIKEWISE:
 * As Pitch Angle Increases - AOA Increases
 * As Linear Flow Increases - AOA Increases
 * As Induced Flow Increases - AOA Decreases
 * As Pitch Angle Decreases - AOA Decreases
 * As Linear Flow Decreases - AOA Decreases
 * As Induced Flow Decreases - AOA Increases

2.2	DIFFERENTIATE AND CHARACTERIZE THE SYMMETRICAL AND NONSYMMETRICAL AIRFOILS.


 * SYMMETRICAL: Same shape & size above & below the chord line *NONSYMMETRICAL: Different shape & size above & below the chord line. When LIFT is created on a nonsymmetrical airfoil a TWISTING moment is created due to the unequal forces above & below the airfoil.
 * NOTE: TH-57 uses a "Droop-snoot" airfoil (nonsymmetrical) which provides good characteristics at high AOA and produces very little twisting moments.

2.3 DEFINE GEOMETRIC TWIST AND STATE WHY IT IS USED IN HELICOPTER DESIGN.


 * Geometric twist is the intentional twisting of the rotor blade to help more equally distribute the Aerodynamic Force (i.e., Lift) along the blade. It is needed because more lift is present at the tip than the root because there is more linear flow at the tip because the tip is traveling much faster than the root. The pitch of the blade is reduced from the root outward to the tips.
 * The TH-57 has 5 degrees of geometric twist.

2.4	DEFINE FLAPPING:
 * Vertical blade movement. Allows the rotor disk to be tilted and compensates for dissymmetry of lift

2.5	DEFINE GEOMETRIC IMBALANCE.
 * Geometric imbalance is an out of balance state created when rotor blade centers of mass are not equidistant from the center of rotation like when they flap.

2.5.1	STATE HOW GEOMETRIC IMBALANCE AFFECTS HORIZONTAL BLADE MOVEMENT (LEAD/LAG)
 * When the rotor disc is tilted, the radius of the center-of-mass for the rotor blades is changed. In order to maintain a constant linear velocity, the rotational velocity must change whenever the radius changes. As the disc is tilted, the radius of the down blade is increased and therefore the rotational velocity for that blade must decrease (i.e., LAG). The radius for the up-going blade is decreased and therefore its rotational velocity must increase (LEAD).

2.6	DIFFERENTIATE AND CLASSIFY THE THREE TYPES OF ROTOR HEADS USED TODAY.
 * Fully Articulated Hub, rotors move on a lead lag hinge.
 * Rigid hub with flexible blade roots, rotors accomplish lead and lag because they are made of a flexible composite at the root which functions as a virtual lead-lag hinge.
 * Teetering Hub (TH-57) – Rather than allow lead and lag geometric imbalance is overcome by under slinging a two bladed rotor.

2.6.1	STATE THE METHOD BY WHICH FLAPPING IS ACCOMPLISHED IN EACH SYSTEM.
 * RIGID: The blades bend to allow flapping, lead/lag, and pitch control. (Rotor head made of composite material)
 * SEMI-RIGID: Uses horizontal hinge pin in center of rotor head to allow flapping. Uses underslinging to compensate for geometric imbalance instead of allowing lead/lag.
 * FULLY ARTICULATED: Uses vertical hinge pins for independent movement in the horizontal plane (Lead/Lag, Hunt/Drag) and horizontal hinge pins for independent movement in the vertical plane (flapping). No movement is permitted between the MRH and the mechanical axis.

2.6.2	STATE THE METHOD BY WHICH GEOMETRIC IMBALANCE IS COMPENSATED FOR OR ELIMINATED IN EACH SYSTEM.
 * Geometric imbalance can be overcome in two ways.
 * 1. by allowing the individual blades to move independently in the horizontal plane the blades can LEAD and LAG as necessary when the rotor disc is tilted to compensate for the changing radii of the blades. This is accomplished by using a Vertical Hinge Pin for the rotor blades in a Fully Articulated Rotor Head and by allowing bending of the Rigid rotor head.
 * 2. Semi-rigid rotor heads use underslinging to compensate for geometric imbalance. By underslinging the rotor head, as the rotor head tilts, the radii of both blades will increase or decrease equally and therefore no lead/lag is necessary.

CHAPTER THREE
3.1	DRAW AND LABEL A POWER REQUIRED/POWER AVAILABLE CHART AND A FUEL FLOW VERSUS AIRSPEED CHART.
 * See charts.

3. 1.1 	IDENTIFY MAXIMUM ENDURANCE AIRSPEED.


 * 50 Knots for the TH-57 (lowest point on power required curve)
 * NOTE: if partial engine power is lost (underspeed), it is best to fly max endurance airspeed.

3.1.2	IDENTIFY MAXIMUM RATE OF CLIMB AIRSPEED.


 * 50 Knots (Lowest point on power required curve, maximum power available)

3.1.3	IDENTIFY BEST RANGE AIRSPEED AND STATE THE EFFECTS OF WIND COMPONENTS ON BEST RANGE AIRSPEED.


 * Best range airspeed is the point where a line drawn from the origin is tangent to the power required curve. A tailwind will shift the origin left & therefore reduce best range airspeed, but increase distance. A headwind will shift the origin right and therefore increase best range airspeed, but decrease distance. 72 KIAS for the TH-57.

3.2	DEFINE TORQUE EFFECT.


 * Due to the momentum of the advancing blade on the right, there is an equal & opposite reaction (Torque) which causes the helo to rotate to the RIGHT.

3.2.1	STATE THE MEANS BY WHICH WE COUNTERACT TORQUE.


 * By use of a tail rotor which produces a thrust to the right, creating left yaw and thereby counteracting torque.

3.2.2	STATE THE MEANS BY WHICH WE CONTROL THE HELICOPTER ABOUT THE VERTICAL AXIS.


 * A LEFT yaw is accomplished by INCREASING tail rotor thrust and thereby OVERCOMPENSATING for the torque effect. A RIGHT yaw is accomplished by DECREASING tail rotor thrust and thereby UNDERCOMPENSATING for the torque effect.

3.2.3	STATE THE MEANS BY WHICH A MULTI-ROTOR HEADED SYSTEM COUNTERACTS TORQUE.


 * By using an even number of rotor systems rotating in opposite directions.

3.3	STATE THE EFFECT THE TAIL ROTOR WILL HAVE ON POWER AVAILABLE TO THE MAIN ROTOR.


 * The tail rotor uses 5 to 15% of the total power available, therefore leaving 85-95% for the main rotor.

3.4	STATE THE TWO MEANS BY WHICH TAIL-ROTOR LOADING IS REDUCED IN FORWARD FLIGHT.


 * The WEATHER-VANING effect of the fuselage and the horizontal lift created by the VERTICAL STABILIZER. The vertical stabilizer effectiveness increases as airspeed increases; at approximately 95 kts and above, you actually have to add right rudder to maintain heading.

3.5	STATE ONE PROBLEM CREATED BY USE OF A TAIL ROTOR SYSTEM TO COUNTERACT TORQUE.


 * The sideward thrust of the tail rotor causes the helo to drift right. This is called translating tendency. To counteract this right drift you must add a small amount of left cyclic. This causes the helo to take off right skid first and to hover left skid low. *REMEMBER: During engine loss in a hover you must take out this correction; otherwise the helo will drift left.

3.6	DEFINE VIRTUAL AXIS, MECHANICAL AXIS, AND CENTER-OF-GRAVITY.


 * MECHANICAL AXIS: The extension of the center line of the rotor mast (the actual axis of rotor head).
 * VIRTUAL AXIS: An axis perpendicular to the plane of rotation. As the rotor tilts the virtual axis tilts and remains perpendicular to the plane of rotation.
 * CENTER-OF-GRAVITY: The balancing point for a body

3.6.1	STATE THE RELATIONSHIP BETWEEN CENTER-OF-GRAVITY, MECHANICAL AXIS, AND THE VIRTUAL AXIS.


 * The center-of-gravity should be in-line with the mechanical axis but realistically cannot always be. When not in line the cyclic must be displaced to compensate for the unbalanced CG condition. During flight, as the virtual axis tilts (to change helo direction) the CG attempts to align with virtual axis.

3.7 LIST THE FORCES ACTING ON THE MAIN ROTOR HEAD.


 * CENTRIFUGAL FORCE (greatest force, proportional to square of Nr), *AERODYNAMIC FORCE

3.7.1 DEFINE CENTRIFUGAL FORCE AND AERODYNAMIC FORCE.


 * Centrifugal force is the outward force created by the rotation of the main rotor head. The large centrifugal force is what allows the weight of the helicopter to be supported by the flexible rotor blades. Aerodynamic force is the summation of all forces involved in creating lift. (Lift, Induced Drag, Profile Drag)

3.7.2 DEFINE CONING AND THE CONING ANGLE


 * CONING is the upward displacement of the main rotor blades due to the interaction of centrifugal force and aerodynamic force.
 * CONING ANGLE is the angle between the tip-path-plane and the main rotor blades. *NOTE: Weight, G-force, and RPM affect coning angle. If Lift (aerodynamic force) is constant and Nr increases, coning angle decreases.


 * If Nr is constant and lift (aerodynamic force) increases, coning angle increases. Low RPM and excessive weight can cause excessive coning.

3.8	INTERPRET HOW A VORTEX IS FORMED AND HOW IT AFFECTS THE EFFICIENCY OF THE ROTOR SYSTEM.


 * High pressure air under the airfoil swirls around the blade to fill the low pressure area on top of the blade. The greater the LIFT, the greater the pressure differential, and therefore the greater the main rotor blade vortices. Since this transfer of air decreases the pressure differential between the top and bottom of the rotor blade, it should be obvious that the formation of a Vortex DECREASES the rotor system efficiency.


 * NOTE: These MRB vortices occur at both the Tips of the blades and the Root End of the blades (Hub).

3.9	STATE THE EFFECT MAIN ROTOR VORTICES HAVE IN THE TAIL ROTOR AT LOW AIRSPEEDS.


 * At airspeeds less than 30 kts and with winds from the forward port side of the helo (285 to 315 degrees) the Main Rotor Vortices may be directed onto the tail rotor, which will increase the AOA of the tail rotor which produces the same effect as adding left pedal. Therefore, you must anticipate this and be ready to apply left pedal during a right turn.

3.10	DEFINE GROUND EFFECT BY STATING THE TWO EFFECTS WHICH CAUSE IT.


 * Ground effect is a favorable aerodynamic phenomenon which requires less power when the helicopter is within one rotor diameter of the ground.


 * 1. Most important is the reduction of the velocity of the induced flow because the ground interrupts the air flow under the helo. As the induced flow decreases, induced drag decreases and tilts the lift vector more vertical. Therefore, you can reduce pitch (further reducing drag) and still generate the same amount of lift.
 * 2. Reduction in rotor TIP vortex formation.

3.10.1 	STATE HOW GROUND EFFECT AFFECTS POWER REQUIRED.


 * Ground effect increases rotor efficiency therefore reducing power required. Ground effect begins at approximately one rotor diameter from the earth. It is best over smooth paved surfaces.

3.11 DEFINE GROUND VORTEX AND WHAT CAUSES IT.


 * Ground vortex is when the aircraft overruns its own vortex as it accelerates. As the aircraft flies through the vortex, induced flow is increased, which increases power required.

3.12	DEFINE TRANSLATIONAL LIFT BY STATING THE PHENOMENON WHICH CAUSES IT.


 * As the helo moves from a no-wind hover to forward flight, it passes through translational lift, which increases rotor efficiency due to more air flow through the system per unit of time AND because it is now capable of outrunning its vortices which reduces induced flow. Translational lift begins with forward movement, Effective translational lift occurs at 10- 15 knots, Max translational lift occurs at 51 knots.

3.12.1 	STATE HOW TRANSLATIONAL LIFT AFFECTS POWER REQUIRED.


 * Since translational lift increases rotor efficiency it REDUCES POWER REQUIRED.

3.13	STATE THE EFFECT OF DISSYMMETRY OF LIFT ON THE HELICOPTER.


 * In forward flight the advancing blade sees an increase in linear flow, which increases the AOA on that blade. The increase in AOA causes lift to increase on the advancing blade. Likewise, the retreating blade sees a decrease in linear flow, a decrease in angle of attack and therefore a decrease in lift.

3.13.1	STATE THE METHODS BY WHICH DISSYMMETRY OF LIFT IS OVERCOME IN VARIOUS ROTOR SYSTEMS.
 * In forward flight, the advancing side will generate more lift, thus developing a rolling moment. To equalize this dissymmetry of lift in forward flight we allow the blades to flap. The advancing blade, which encounters higher lift, begins to flap upward. The retreating blade, which encounters less lift, flaps downward.


 * See OBJECTIVE 2.6.1 for how flapping is permitted in the three types of rotor heads.

3.14 	STATE THE EFFECT OF PHASE LAG ON THE CONTROL OF A HELICOPTER.


 * Because of phase lag you must increase Main Rotor Blade AOA 90 degrees prior to the position of desired maximum lift.

3.15 	DEFINE BLOWBACK BY STATING THE CAUSE.


 * Dissymmetry of lift and phase lag cause blowback. It is the pitch-up tendency of the aircraft as it accelerates and the pitch-down tendency as the aircraft decelerates. The advancing blade (90 degree position) flaps up due to an increase in lift, an increase in lift at the 90-degree position will manifest itself 90 degrees later (due to phase lag) over the nose. An increase in lift over the nose tends to make the nose pitch up (i.e., blowback). The retreating blade causes a loss of lift over the tail, which also causes the nose to pitch up.

3.15.1	DESCRIBE THE EFFECT BLOWBACK HAS ON HELICOPTER ATTITUDE AND AIRSPEED.


 * As airspeed increases, dissymmetry of lift increases, therefore flapping must increase. As flapping increases, blowback increases, and therefore the nose-up tendency increases, which requires a constant nose-down trimming process. The opposite is true when airspeed decreases. As airspeed decreases, dissymmetry of lift decreases, therefore flapping must decrease. As flapping decreases, blowback decreases and therefore the nose-down tendency increases, which requires a constant nose-up trimming process.

3.16	IDENTIFY FORE-AND-AFT ASSYMMETRY OF LIFT BY STATING TWO EFFECTS WHICH CAUSE IT AND HOW IT AFFECTS HELICOPTER FLIGHT.


 * 1. Coning: The combination of forward airspeed and coning results in less induced flow and greater AOA (and greater lift) for the blade over the nose than the blade over the tail.
 * 2. Non-uniform Induced Flow: i.e., Transverse flow. As the helo moves forward through the air the blade over the nose sees clean undisturbed air while the blade over the tail sees the air which is disturbed by rotor vortices. Therefore the lift over the nose is greater than the lift over the tail. This fore & aft assymmetry of lift causes vibrations to be felt at the 90 / 270 degree position (i.e., lateral vibrations) and is greatest at 15 knots.

CHAPTER FOUR
4.1	DEFINE AUTOROTATION. 4.2	DRAW AND LABEL A BLADE ELEMENT DIAGRAM FOR AUTOROTATION. 4.3	DEFINE PRO-AUTOROTATIVE FORCE. 4.4	DEFINE ANTI-AUTOROTATIVE FORCE. 4.5	STATE THE THREE PHASES REQUIRED TO TRANSITION FROM POWERED TO UNPOWERED FLIGHT.
 * Flight without engine power where the air approaching from below the rotor disc keeps the rotor turning at an operational speed (i.e., Self-induced rotation of the rotor system in unpowered flight). May be divided into 3 distinct phases: Entry, Steady State Descent, and Deceleration and touchdown.
 * See image at right.
 * The horizontal component of the lift vector which is tilted forward is the pro-autorotative force.
 * In-plane drag is the sum of all decelerating forces in the plane of rotation and is the anti-autorotative force.
 * The three phases of the ENTRY are: 1. Reduce In-Plane drag to stop RPM decay by lowering the collective. 2. Reversal in induced flow (As helo begins to descend induced flow reverses). 3. Control In-Plane Drag (Nr) by varying the pitch of main rotor blades with the collective.

4.6	STATE THE EFFECTS OF A FLARE IN AN AUTOROTATION.
 * The cyclic flare (initiated at 100-75 ft AGL) tilts the rotor disc aft and increases induced flow. This causes the relative wind to shift further down, increases AOA, and the lift vector is increased and tilted more forward (increasing pro-autorotative force) which causes:
 * 1. Sink Rate to Decrease
 * 2. Airspeed to Decrease
 * 3. Rotor RPM to Increase

4.7	STATE THE TWO VARIABLES THAT AFFECT AUTOROTATIVE DESCENT.
 * AIRSPEED & ROTOR RPM Minimum Rate of Descent airspeed is found at the lowest point on the power required vs. airspeed chart (50 kts). Nr other than optimum (94-95%) increases rate of descent.
 * HIGH GROSS WEIGHTS AND HIGH DENSITY ALTITUDES DO NOT AFFECT RATE OF DESCENT. HOWEVER, THEY DO AFFECT:
 * 1. MINIMUM RATE OF DESCENT ROTOR RPM (increases)
 * 2. ENERGY REQUIRED TO ARREST RATE OF DESCENT DURING FLARE

4.8	STATE THE PURPOSE OF THE HEIGHT-VELOCITY DIAGRAM.


 * To identify portions of the flight envelope from which a safe landing can be made in the event of an engine failure.

CHAPTER FIVE
5.1	DEFINE RETREATING BLADE STALL BY STATING ITS CAUSE AND THE EFFECTS ON HELICOPTER FLIGHT.
 * As airspeed increases the retreating blade linear flow is reduced. The retreating blade must still produce an amount of lift equal to that of the advancing blade, therefore as lift is list, the blade flaps down, decreasing induced flow. This causes the AOA on the retreating blade to increase. Eventually as airspeed increases, the blade will exceed the critical AOA and will stall. The effect on the helicopter is:
 * 1. 2:1 Vibration level increases
 * 2. Pitch-up of the Nose (Left blade, 270, stalls & due to phase lag loose lift over the tail & nose pitches up)
 * 3. Rolling tendency toward the stalled side (left)
 * During blade stall there will be three factors present:
 * 1. Up collective (increased power for forward A/S - increased blade pitch)
 * 2.	Forward Cyclic (For increased forward A/S - causes retreating blade pitch angle to increase)
 * 3.	Increased Blade flapping due to high airspeed
 * Factors which increase the potential for blade stall:
 * High Blade Loading (i.e., high Gross Weights / G-loading)
 * Low Rotor RPM
 * Steep or Abrupt Turns
 * Turbulent Air
 * High Density Altitude
 * High Drag Configurations (external sources)

5.1.1 	STATE THE SOLUTION TO RETREATING BLADE STALL. 5.2 DEFINE COMPRESSIBILITY EFFECT BY STATING ITS CAUSE AND THE EFFECTS ON HELICOPTER FLIGHT. significant air density changes. As the blade tip approaches the speed of sound a compression wave forms at the leading edge of the blade and all changes in velocity and pressure take place sharply and violently. 5.2.1 	STATE THE SOLUTION TO COMPRESSIBILITY EFFECT. 5.3 DEFINE VORTEX RING STATE BY STATING ITS CAUSE AND THE EFFECTS ON HELICOPTER FLIGHT. 5.3.1 STATE THE RECOVERY TECHNIQUES FOR THE VORTEX RING STATE. If impact is imminent: 5.4	DEFINE POWER REQUIRED EXCEEDS POWER AVAILABLE BY STATING ITS CAUSE AND THE EFFECTS ON HELICOPTER FLIGHT. 5.4.1 	STATE THE RECOVERY TECHNIQUE FOR POWER REQUIRED EXCEEDS POWER AVAILABLE. 5.5	DEFINE GROUND RESONANCE BY STATING ITS CAUSE AND THE EFFECTS ON HELICOPTER FLIGHT. 5.5.1	STATE TWO ALTERNATIVE TECHNIQUES TO REMEDY GROUND RESONANCE. 5.6	DEFINE DYNAMIC ROLLOVER BY STATING THE TWO ESSENTIAL ELEMENTS REQUIRED FOR ROLLOVER TO OCCUR. 5.7	DEFINE MAST BUMPING BY STATING ITS CAUSE AND THE EFFECT ON THE HELICOPTER. 5.7.1 	STATE THE MAJOR AND MINOR CAUSES OF MAST BUMPING. 5.7.2 	STATE THE INDICATIONS OF MAST BUMPING. 5.7.3 	STATE THE RECOVERY TECHNIQUE FOR MAST BUMPING. 5.8	STATE THE THREE CATEGORIES OF HELICOPTER VIBRATIONS. 5.8.1 STATE THE COCKPIT INDICATIONS FOR EACH CATEGORY. 5.8.2 STATE THE POSSIBLE SOURCES FOR EACH CATEGORY.
 * Avoid Blade Stall by proper preflight planning. If encountered accomplish one or more of the following:
 * 1. Decrease severity of maneuver
 * 2. Decrease collective pitch
 * 3. Reduce airspeed (aft cyclic even though nose is pitching up)
 * If operational necessity requires continued high speed flight:
 * 4. Increase Rotor RPM
 * 5. Descend to lower altitude
 * 6. Reduce Gross Weight
 * At high airspeeds the advancing blade creates large pressure changes which result in
 * Effects on the helicopter are:
 * 1. Increase the power required to maintain rotor RPM
 * 2. Vibration and rotor roughness
 * 3. Cyclic shake
 * 4. An undesirable structural twisting of the blade shifting the aerodynamic center rearward.
 * The solutions is the same as retreating blade stall except SLOW Nr instead of increase.
 * Vortex ring state (Power settling) is an uncontrolled rate of descent caused by the helicopter rotor encountering disturbed air as it settles into its own downwash. (Airflow is upward in center of rotor and downward in outer portion of rotor resulting in zero net thrust). This occurs when descent rate exceeds 800 feet per minute and airspeed is less than 40 knots.
 * Indications:
 * 1. Rapid descent rate increases
 * 2. Increase overall vibration level
 * 3. Loss of cyclic effectiveness
 * 4. Loss of tail rotor authority
 * 1.	Forward cyclic to gain airspeed (this allows the helo to get away from its vortex rings.
 * 2.	Slight decrease in collective pitch (this reduces lift, which reduces the size of the vortex rings)
 * 3.	Level A/C to conform to terrain.
 * Conditions of high gross weights, high G-loading, rapid maneuvering (i.e., quick stops),high density altitude, loss of ground effect, loss of wind effect (descending below a tree line), change of wind direction, and low airspeeds can cause power required to exceed power available (Settling with Power) and create an uncommanded descent rate.
 * Avoid by:
 * 1.	Proper preflight planning
 * 2.	Avoid excessive maneuvering during high/hot and/or high gross weight/marginal power available.
 * 3.	Avoid high descent rates @ low altitudes, which will require large power inputs to arrest the helicopter's descent.
 * 4.	Avoid downwind landings and takeoffs.
 * 5.	Maintain awareness of wind speed and direction.
 * 6.	Maintain awareness of factors leading to settling with power.
 * Indications:
 * 1. 	Increased rate of descent
 * 2.	Drooping Nr
 * 3. 	Max Ng
 * 4. 	High TOT
 * 5. 	Possible decrease in tail rotor effectiveness (if rotor RPM drops too low)
 * 1. 	Nr - Maintain
 * 2. 	RPM Switch Full Increase
 * 3. 	Airspeed increase/decrease to 50 KIAS (min. power req)
 * 4. 	Level Wings (Decrease AOB)
 * 5. 	Jettison - As required
 * Normally associated with the fully articulated rotor system (possibility reduced by using lead/lag dampers). It is a DESTRUCTIVE OSCILLATION caused when helo is in contact with the ground and the blades are displaced (jolted) due to a gust of wind, sudden control movement or hard landing. CG then spirals violently outward.
 * 1. Lift off into a hover (PRIMARY METHOD).
 * 2. Land, secure engine and apply rotor brake (ALTERNATE METHOD).
 * During slope OR crosswind landing & takeoff maneuvers exceeding the critical rollover angle (15 degrees) or exceeding 10 degrees per second will cause the helo to roll over onto its side regardless of cyclic corrections introduced by the pilot. For dynamic rollover to occur two essential elements must exist:
 * 1. Ground pivot point
 * 2. A side force
 * Critical rollover angle is reduced for a right skid down condition, crosswind, lateral CG offset, and left rudder pedal inputs.
 * When landing or taking off, keep aircraft trimmed and do not allow A/C roll rates to build. If roll rates begin to build recover by smoothly lowering the collective.
 * Note: The static rollover angle for the TH-57 is approximately 31 degrees.
 * Mast bumping is a result of excess blade flapping and is the violent contact between the static stop and the mast which causes mast damage and separation.
 * Major (most common) causes:
 * 1. Low "G" maneuvers
 * 2. Large rapid cyclic movements
 * 3. Flight near CG limits
 * 4. Steep slope landings
 * Minor (less common) causes
 * 1. Max sideward or rearward flight
 * 2. Blade stall conditions
 * If flapping exceeds the design value, the static stop will contact the mast. It is the violent contact between the static stop and the mast during flight that causes mast damage or separation. This contact must be avoided at all costs.
 * Recovery depends on condition causing the mast bumping.
 * Start/Shutdown
 * Cyclic:	Move to stop bumping
 * Slope Landing
 * Cyclic:	Move toward center to stop bumping; reestablish hover
 * Engine Failure at high forward airspeed
 * Cyclic:	Move aft to maintain positive G (positive thrust), retain Nr and avoid mast bumping during auto entry.
 * Low G maneuvers (below + 0.5 G (other than nose high)
 * Cyclic:	AFT, then center laterally to regain positive G (positive thrust) on the rotor & maintain Nr,
 * Collective: Judiciously increase if possible
 * Pedal: As required Cyclic: Neutral
 * Nose high, low airspeed Rear/Side Flight
 * Cyclic: Move slightly toward center
 * Pedal: Bring nose into wind
 * Low, Medium, and High
 * See below
 * LOW
 * 1: 1 LATERAL: MRB out of balance
 * 1: 1 VERTICAL	MRB out of track (most common)
 * 2:1	Inherent in two-bladed helo. Increase indicates worn rotating control part or rotor hub part.
 * MEDIUM
 * 4:1 TO 6:1	Change in A/C ability to absorb normal vibrations. Loose component. (landing gear most common), loose cargo etc.
 * HIGH too fast to count, a buzz
 * Anything that rotates or vibrates at the speed of the buzz (e.g. transmission, engine, driveshaft) if it is in the pedals it is probably the tail rotor.

=Aero Question Bank=

Questions
1. Air at 50% humidity.
 * A. Is just as dense as air at 100% humidity.
 * B. Is half as dense as dry air.
 * C. Has greater density than air at 100% humidity
 * D. Humidity does not affect the density of the air.

2. Pressure altitude is based on which of the following elements?
 * A. Standard atmosphere
 * B. Humidity of 50%
 * C. Atmospheric pressure of 29.92.
 * D. Density altitude

3. What is pressure altitude?
 * A. Altitude incorporating temperature correction.
 * B. Standard altitude at sea level with 50% humidity
 * C. Altitude of a given atmospheric pressure in the standard atmosphere.
 * D. Altitude corrected for temperature and humidity.

4. Aircraft altimeters are constructed for the pressure height relationship
 * A. and there is a mechanical correction factor for humidity
 * B. and will always give you true altitude
 * C and can determine density altitude by dialing in 29.92
 * D. and can determine pressure altitude by dialing in 29.92

5. Density altitude is pressure altitude corrected for
 * A. pressure and wind
 * B humidity and pressure
 * C. humidity and temperature
 * D. Temperature and pressure

6. On a cool, dry day one would expect the
 * A. density altitude to be high
 * B. density altitude to be low
 * C. air density to be low
 * D. air density and the density altitude to be the same.

7. When computing density altitude, 50% relative humidity adds ____ to dry air density altitude.
 * A. 50% of the pressure altitude
 * B. 500’ plus 25% of the humidity
 * C. 50’
 * D. 500’

8. As temperature increases above standard day conditions, density altitude
 * A. increase
 * B. remain the same
 * C. decrease
 * D. fluctuate rapidly

9. As density altitude increases, the _____ will increase because the _______ is/are less efficient
 * A. power available…rotor blades
 * B. power required… engine
 * C. power available… engine
 * D. power required…rotor blades

10. An increase in air density will
 * A. increase density altitude
 * B. have no effect on the helicopter below its hovering ceiling
 * C. increase power available
 * D. decrease rotor efficiency

11. What is the resultant of the vertical component (induced flow) and the horizontal component (linear flow).
 * A. Flight path
 * B. Aerodynamic force
 * C. Coning angle
 * D. Relative wind

12. In a rotating system, the linear flow is ______ at the tip of the blade and _____ at the root.
 * A. constant …varying
 * B. uniform…irregular
 * C. greatest…least
 * D. least…greatest

13. As induced flow decreases, the angle of attack.
 * A. increases
 * B. decreases
 * C. remains the same
 * D. cannot be determined

14. Induced flow is perpendicular to the tip-path while linear flow is
 * A. parallel to the relative wind
 * B. perpendicular to the tip-path plane
 * C. parallel to the tip path plane
 * D. perpendicular to the relative wind

15. Within its envelope, when there is an increase in the angle-of-attack, there is a corresponding increase in the
 * A. pitch angle
 * B. lift
 * C. linear flow
 * D. induced flow

16. Induced drag is created as a result of the production of ______ and in-plane drag is the sum of the ______ _____ in the plane of rotation.
 * A. thrust... lifting forces
 * B. lift…pro-authoritative forces
 * C. lift…decelerating forces
 * D. thrust…anti-rotative forces

17. Power required to rotate a rotor system is directly proportional to
 * A. inertia
 * B. power available
 * C. momentum
 * D. in-plane drag

18. The major forces acting on the rotor blades are 19. What two forces determine coning angle?
 * A. centrifugal and aerodynamic
 * B. centrifugal and drag
 * C. lift and drag
 * D. weight and centrifugal
 * A. G-loading force and centralization
 * B. Aerodynamic force and lift
 * C. Aerodynamic force and centrifugal force
 * D. In-plane drag and g-loading force

20. What will happen to the fuselage when you add power?
 * A. Yaw to the right due to torque effect
 * B. Yaw to the right due to anti-torque.
 * C. Yaw to the left due to anti-torque
 * D. Yaw to the left due to torque effect.

21. In a single rotor helicopter, movement of the directional control petals will:
 * A. vary rpm of the tail rotor
 * B. vary the collective pitch of the tail rotor blades
 * C. tilt the tail rotor
 * D. control the aircraft movement about the pitch axis

22. Which of the following function(s) does the tail rotor serve?
 * A. To control the aircraft about the lateral axis
 * B. As an anti-torque device
 * C. Both A and B above
 * D. To control the aircraft about the pitch axis.

23. A aircraft having an even number of rotor systems of the same mass and design rotating in opposite directions
 * A. is not as efficient as tail rotor helicopters
 * B. cannot control movement about the vertical axis
 * C. is effective because the rotor systems operate at different speeds
 * D. is effective since both torque effects balance each other out

24. When making a vertical takeoff, what will happen to the tail rotor power requirements?
 * A. Remain the same
 * B. Increase
 * C. Decrease
 * D. Fluctuate rapidly

25. During a no-wind hover, a pedal turn to the ____ in the TH-57 would cause the tail rotor to demand ______ power.
 * A. right …less
 * B. right…more
 * C. left…less
 * D. right…the same

26. At cruise airspeed the rudder pedals are approximately even as tail rotor loading decreases due to:
 * A. linear flow increasing across the advancing blade
 * B. wing and horizontal stabilizer
 * C. weather vaning and the vertical stabilizer

27. Since the tail rotor is a thrust producer, in what direction does the tail rotor cause the helo to drift?
 * A. Left
 * B. Right
 * C. Forward
 * D. Backward

28. With an engine loss in a hover, the pilot must move the _____ to the ______ when the failure occurs as the tail rotor effect is eliminated.
 * A. collective…up position
 * B. collective…down positon
 * C. cyclic…left
 * D. cyclic…right

29. The main rotor is tilted to the ____ in order to counter the effect of the tail rotor, thus the helicopter will tend to take off ____ skid first.
 * A. left…right
 * B. right…left
 * C. left…left
 * D. right…right

30. The virtual axis of a rotor system remains perpendicular to the
 * A. relative wind
 * B. tip-path plane
 * C. mechanical axis
 * D. in-plane thrust

(missing 31-35)

36. Geometric twist on a rotor blade is limited due to its negative characteristics in which of the following situations.
 * A. Forward flight
 * B. Flaring
 * C. Ground effect
 * D. Autorotation

37. Rotor blade “pitching moments” are minimized by using a _____ airfoil..
 * A. tapered
 * B. non symmetrical
 * C. neutral stable
 * D. symmetrical

38. In order to tilt the rotor disk forward, blade pitch must decrease at the _____ and increase at the ____ positions.
 * A. 270…90
 * B. 180…36
 * C. 360…180
 * D. 90…270

39. During the initial phases of dissymmetry of lift, the resulting flapping effect, the retreating blade feels decreasing linear flow, thus decreasing ______ and decreasing aerodynamic force causing the blade to flap____.
 * A. induced flow…down
 * B. AOA…up
 * C. AOA…down
 * D. induced flow…up

40. Dis-symmetry of lift is eliminated in a full articulated rotor head by
 * A. Horizontal hinge pins
 * B. Vertical hinge pins
 * C. blade dampers
 * D. underslung mountings

41. What effect does airspeed have on rotor blade flapping?
 * A. No effect
 * B. Increased airspeed increases flapping
 * C. Increased airspeed decreases flapping
 * D. Decreased airspeed increases retreating blade flapping

42. What statement reflects blade flapping in forward flight?
 * A. Affects the pitch angle on the blades
 * B. Compensates for geometric imbalance
 * C. Corrects for blade imbalance
 * D. Varies the angle of attack on the blades.

43. Because of the effects of the blowback while accelerating in forward flight, what must you do to maintain a level flight attitude?
 * A. Hold the cyclic constant
 * B. Trim in nose up
 * C. Trim in nose down.
 * D. Yaw the helicopter and reduce lag.

44. Flapping action of rotor blades while transition to forward flight will:
 * A. Decrease with increases in airspeed
 * B. Decrease rotor thrust
 * C. Increase collective pitch
 * D. Cause blowback.

45.	What will occur when the centers of mass in the rotor blades are at different radii to the mechanical axis?


 * A.Geometric imbalance
 * B.Geometric precession
 * C.Flapping
 * D.Gyroscopic precession.

46.	Which of the following statements is characteristic of geometric imbalance in the semi rigid rotor system?


 * A.Cannot be eliminated due to the spanwise rigidity of the blades
 * B.Is compensated by adjustment of the blade root counter weights,
 * C.Is nearly eliminated by aligning the blade's center of mass with the center line of the flapping 	hinge
 * D.Is compensated through the alignment of the blade's centers of pressure and the rocking hinge

47.	Translational lift increases available lift due to: (answer debated between B & C, definition says mass flow but mass flow is due to increased linear flow of air)


 * A.increased linear flow
 * B.decreased linear flow
 * C.increased mass flow
 * D.increased induced flow

48.	One phenomena which decreases power required while hovering in ground effect is:


 * A.reduction of rotor tip vortices
 * B.increased linear flow
 * C.reduction of linear flow
 * D.flapping

49.	When first transitioning into forward flight the aircraft will settle because of


 * A.reduced induced flow
 * B.transverse flow
 * C.rotor vortices
 * D.reduced linear flow

50. Given a plot of power available and required versus velocity, which of the following statements is characteristic of maximum rate of climb velocity


 * A.It is that velocity that corresponds to the point on the power required curve where a line drawn from the original becomes a tangent.
 * B.It is that velocity where, there is maximum fuel consumption.
 * C.It is that velocity corresponding to range.
 * D.It is that velocity where there is maximum excess power.

51. The lateral vibration as a rotor system goes into forward flight is caused by


 * A.transverse flow
 * B.ground resonance
 * C.induced drag
 * D.blade flapping

52. As the helicopter arrives within one rotor diameter's distance of a smooth surface relative wind becomes more horizontal due to a/an:


 * A.increase in linear flow
 * B.decrease in induced flow
 * C.decrease in linear flow
 * D.increase in induced flow

53. Ground effect


 * A.increases with an increase in airspeed
 * B.decreases with an increase in airspeed
 * C.is not affected by airspeed
 * D.is most effective when greater than one rotor diameter from the ground

54. Ground effect is caused by a/an:


 * A.decrease in induced flow and decrease in wing tip vortex rings
 * B.increase in induced flown and decrease in wing tip vortex rings
 * C.decrease in induced flow and increase in wing tip vortex rings
 * D.increase in induced flow and increase in wing tip vortex rings

55. The induced flow in an autorotation is:


 * A.perpendicular to the relative wind
 * B.perpendicular to the induced drag
 * C.same as in powered flight
 * D.reversed from powered flight

56. What is the self induced rotation of a rotor system in unpowered flight?


 * A.Autorotation'
 * B.Inertia
 * C.Autogyration
 * D.Rotary flight

57. If the resultant aerodynamic force vector of a blade is forward of the vertical, then the blade element is:


 * A.aerodynamically stalled
 * B.pro autorotative
 * C.experiencing translational lift
 * D.in ground effect

58. When the pro autorotative forces equal in plane drag, the rotor RPM will be:


 * A.fluctuating
 * B.decreasing
 * C.increasing
 * D.stabilizing

59. The force which enables the pilot to regain RPM during autorotative flight is:


 * A.momentum
 * B.anti autorotative force
 * C.pro autorotative force
 * D.inertia

60. Anti autorotative force _____when the pilot _____ the collective in autorotative flight.


 * A.increases ... lowers
 * B.does not change ... lowers
 * C.decreases . . . raises
 * D.decreases ... lowers

61.	During the transitions to unpowered flight, ____ maintains rotor speed until induced flow is fully reversed.


 * A.action/reaction
 * B.induced drag
 * C.inertia
 * D.centrifugal force

62.	In order to transition from powered to unpowered flight you must do which, if any, of the following actions?


 * A.Reduce induced flow, reverse drag. regain and maintain RPM
 * B.Reduce induced flow, reduce in plane drag. regain and maintain RPM
 * C. Reduce in plane drag. regain and maintain RPM
 * D.Reduce induced flow, reverse in plane drag, regain and maintain RPM

63. During an autorotation, the inner section of the rotor system will be _____ due to the _____.


 * A.anti autorotative ... large linear flow
 * B.pro autorotative ... large induced flow
 * C.stalled ... excessive angle of attack
 * D.pro autorotative ... large angle of attack

64. During the flare at the end of an autorotation the ____ flow vector which increases lift, slows airspeed and _______ RPM.


 * A.linear ... decreases
 * B.linear ... increases
 * C.induced ... increases
 * D.induced ... decreases

65. An autorotative flare will increase rotor RPM and decrease


 * A.A/S and rate of descent
 * B.engine RPM and rate of descent
 * C.engine Ng and rate of descent
 * D.A/S and engine RPM

66. Two factors that affect autorotative rate of descent are:


 * A.density altitude and airspeed
 * B.airspeed and rotor RPM
 * C.rotor RPM and density altitude
 * D.density altitude and gross weight

67.	Rotor speeds above the optimum RPM


 * A.will cause an increase in the rate of descent
 * B.will cause a decrease in the rate of descent
 * C.will not effect rate of descent
 * D.will not improve the range that can be traveled

68. Concerning the height velocity (h.v.) diagram, what conditions should be avoided?


 * A.Low altitude, slow airspeed
 * B.High gross weight and density altitude
 * C.High airspeed at altitude
 * D.Low altitude high airspeed

69. What is the lowest point on the power required versus airspeed curve?


 * A.Max endurance airspeed
 * B.Max range airspeed
 * C.Max glide airspeed
 * D.Maximum fuel consumption

70.	Increases in helicopter weight cause what reaction?


 * A.An increase of power required at all airspeeds
 * B.A reduction of power available
 * C.An increase in power available
 * D.An increase of maximum excess power

71. missing

72. Which of the following actions should NOT be the pilot's reaction if the aircraft experiences a sudden nose up pitch while flying at high airspeeds?


 * A.Increase RPM
 * B.Down collective
 * C.Forward cyclic
 * D.Jettison external load

73. An increase in density altitude


 * A.has no effect on maximum endurance airspeed
 * B.has a significant effect on maximum endurance airspeed
 * C.will cause decrease in power required
 * D.will not effect power required

74. _____ in Nr will _____ the airspeed at which you will reach retreating blade stall.


 * A.An increase ... decrease
 * B.A decrease ... increase
 * C.An increase ... increase
 * D.A decrease. . . not effect

75.	Some of the cockpit indications during vortex ring state are


 * A.high Ng, high TOT, low Nr, low Nf
 * B.high descent rate, low airspeed, high Ng
 * C.normal Ng, high descent rate, normal Nr, low airspeed
 * D.high TOT, low airspeed, high descent rate

76.	When does vortex ring state take place?


 * A.When power required exceeds power available
 * B.When power available exceeds power required
 * C.When retreating blade stalls
 * D.When aircraft settles in its own vortex

77. If vibrations and loss of control response occurs during a steep, low airspeed approach, the pilot should immediately take what action (s)?


 * A.Jettison external loads
 * B.Lower collective slightly, apply aft cyclic
 * C.Apply forward cyclic, raise collective slightly
 * D.Lower collective, forward cyclic

78.	With cockpit indications of increased rate of descent, high Ng, high TOT, and decaying Nr, the pilot is experiencing


 * A.retreating blade stall
 * B.vortex ring state
 * C.power required greater than power available
 * D.excessive blade flapping

79.	If settling is encountered with a reduced airspeed at maximum power, what should be regained to insure level flight?


 * A.Original power
 * B.Original torque
 * C.Original airspeed
 * D.Original angle of attack

80.	Your aircraft is power required greater than power available. Placing the collective down will


 * A.decrease the rate of descent at that airspeed
 * B.intensify the vortex ring state
 * C.reverse the airflow, reduce the in plane drag, and stop the rate of descent
 * D.increase the rate of descent

81. A destructive vibration occurring in the rotor system when the aircraft is in contact with the ground is


 * A.blade flapping
 * B.ground effect
 * C.geometric imbalance
 * D.ground resonance

82.	During a ground resonance, if unable to takeoff, the pilot should


 * A.shut down engine and apply rotor brake
 * B.turn aircraft into the wind
 * C.shift center of gravity of aircraft back to normal
 * D.hold the collective down

83.	While in a hover, the helicopter enters uncontrolled leftward flight even though the pilot has applied full right cyclic, the helicopter may


 * A.be entering ground resonance
 * B.be experiencing dynamic rollover
 * C.have entered geometric imbalance
 * D.have exceeded center of gravity limitations

84.	Wingtip vortex intensity is not affected by


 * A.lift
 * B.angle of attack
 * C.weight
 * D.parasite drag

85.	Rotor tip vortices are


 * A.a function of the density altitude
 * B.created by high pressure air above the airfoil flowing to low pressure area beneath it
 * C.created by low pressure air below the airfoil flowing to high pressure area beneath it
 * D.created by high pressure air below the airfoil flowing to low pressure area above it

86.	Helicopter "A" weighs 12,000 lbs. and helicopter "B" weighs 23,000 lbs. Which, if any, of the aircraft produces more intense rotor tip vortices?


 * A.Helicopter "A"
 * B.Helicopter "B"
 * C.There is no difference
 * D.Not enough information given to answer the question

87.	Which of the following characteristics best describes powered flight best range airspeed?


 * A.Unaffected by wind
 * B.Greatest distance traveled for the least fuel burned
 * C.Higher with prevailing tail wind
 * D.Maximum excess power

88.	Powered flight best range airspeed will


 * A.be constant for a given helicopter
 * B.increase with a head wind
 * C.be directly proportional to power available
 * D.decrease with a head wind

89. What are two essential elements for dynamic rollover to occur?


 * A.Vertical force and ground pivot point
 * B.Side force and ground pivot point
 * C.Pitching moment and a loss of tail rotor authority
 * D.Lateral force and an articulated rotor head

90. Which of the following sources may contribute to the rolling tendency during dynamic rollover?


 * A.Flapping
 * B.Geometric imbalance
 * C.Tail rotor side force
 * D.Aft center of gravity

91. Which of the following actions contribute to mast bumping?


 * A.Small rapid cyclic movements
 * B.Unbalanced flight conditions
 * C.Low G maneuvers
 * D.Flight at low density altitudes

92. What is the corrective action if you experience mast bumping during a low G maneuver?


 * A.Smoothly center cyclic and lower collective
 * B.Smoothly apply aft cyclic and center
 * C.Smoothly apply left pedal input and center cyclic
 * D.Smoothly center and apply forward cyclic

93. A ________ frequency vibration is caused by _________


 * A.high ... loose aircraft components
 * B.medium ... the tail rotor
 * C.medium ... the drive shaft
 * D.low ... the main rotor

94. Excessive lateral one to one vibrations are caused by _____ 2 to 1


 * A.A loose aircraft component
 * B.A tail rotor malfunction
 * C.An engine malfunction
 * D.An imbalance in the main rotor

95. During a hovering right turn, you may experience a sudden uncommanded right yaw caused by


 * A.Main rotor vortices
 * B.Increased tail rotor angle of attack
 * C.Sudden left peddle inputs
 * D.CG being located a the forward limit

Answers
1.C 2.A 3.C 4.D 5.C 6.B 7.D 8.A 9.D 10.C 11.D 12.C 13.A 14.C 15.B 16.C 17.D 18.A 19.C 20.A 21.B 22.B 23.D 24.B 25.A 26.C 27.B 28.D 29.A 30.B 31.missing 32.missing 33.missing 34.missing 35.missing 36.A 37.D 38.D 39.C 40.A 41.B 42.D 43.C 44.D 45.A 46.C 47.A 48.A 49.C 50.D 51.A 52.B 53.C 54.A 55.D 56.A 57.B 58.D 59.C 60.D 61.C 62.C 63.C 64.C 65.A 66.B 67.A 68.D 69.A 70.A 71.missing 72.C 73.A 74.C 75.C 76.D 77.D 78.C 79.C 80.D 81.D 82.A 83.D 84.D 85.D 86.B 87.B 88.B 89.B 90.C 91.C 92.B 93.D 94.D 95.A

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