Airflow reversal first occurs at the blade 1 on the 2 side of the disc ? [ Question security ]

Question 247-1 : 1 root 2 retreating 1 tip 2 advancing 1 tip 2 retreating 1 root 2 advancing

Retreating blade stall will occur because ?

Question 247-2 : At increasing forward speed the retreating blade needs an increasingly higher angle of attack at decreasing forward speed the retreating blade needs an increasingly higher angle of attack at increasing forward speed the relative airvelocity on the retreating blade increases at decreasing forward speed the relative airvelocity on the the retreating blade dereases

The symptoms of retreating blade stall are ?

Question 247-3 : Rotor roughness and vibration leading to a possible pitch up and roll to the retreating side rotor roughness and vibration leading to a possible pitch down and roll to the retreating side random roll pitch and yaw leading to a possible pitch down and roll to the retreating side random roll pitch and yaw leading to a possible pitch up and roll to the retreating side

When the helicopter is in level forward flight ?

Question 247-4 : The induced flow velocity is smallest at the front of the disc the induced flow velocity is uniform across the disc the horizontal flow causes an increase in induced flow velocities in comparison with the hover flight the induced flow velocitiy is smallest at the rear of the disc

Inflow roll ?

Question 247-5 : Causes a roll towards the advancing side causes a roll towards the retreating side causes a roll towards the advancing side only if the blades are rotating anti clockwise only occurs if the blades are rotating below normal rotor rpm speed

The degree of control available through the cyclic stick is affected by aircraft ?

Question 247-6 : Aum altitude and cg aum only altitude and aum altitude aum cg and advance angle

Induced power ?

Question 247-7 : Decreases as forward speed increases is unaffected by changes in forward speed is unaffected by changes in forward speed provided altitude remains constant increases as forward speed increases

The flight speed to achieve maximum endurance in a helicopter is ?

Question 247-8 : Near the speed corresponding to the lowest point of the power required curve the speed shown by a tangent from the origin of the power required curve zero because maximum endurance is obtained in the hover the speed corresponding to the maximum point of the power available curve

With an increase in altitude . 1 normally aspirated piston engine power will ?

Question 247-9 : 1 decrease 2 increase 1 increase 2 increase 1 increase 2 decrease 1 decrease 2 decrease

When operating with limited power the speed giving the steepest or maximum ?

Question 247-10 : Is always less than the best endurance speed is always equal to the best rate of climb speed is always equal to the best endurance speed decreases as altitude increases

Compared to a straight and level flight to perform a coordinated turn same ?

Question 247-11 : 1 increased 2 increased 1 increased 2 decreased 1 decreased 2 increased 1 decreased 2 decreased

If the rotor is overpitched the corrective action is to ?

Question 247-12 : Reduce collective pitch and leave engine power constant reduce both engine power and collective pitch increase engine power and collective pitch reduce engine power and leave collective pitch constant

If the helicopter forward speed increases then ?

Question 247-13 : Parasite drag from the fuselage and its components increases parasite power from the fuselage and its components decreases rotor profile power decreases rotor profile drag decreases

Overpitching may occur as a result of ?

Question 247-14 : Applying too much collective pitch at high power settings applying too much rear cyclic in the hover transitioning too rapidly from the hover to forward flight retreating blade stall

To maintain constant rotor rpm during autorotation ?

Question 247-15 : The autorotative moment must be greater than the moment of the blades drag the autorotative moment must equal the moment of the blades drag the autorotative moment must be smaller than the moment of the blades drag the total autorotative force must equal total rotor thrust

The autorotative section of a rotor blade in vertical autorotation is ?

Question 247-16 : In the centre span section of the blade towards the tip of the blade along the full blade span at the root of the blade

In autorotation for maximum range the helicopter must be flown at a speed ?

Question 247-17 : Found by drawing a tangent from the origin to the tas/rate of descent curve which is less than the speed for maximum endurance found from the lowest point on the tas/rate of descent curve equal to the maximum endurance speed

In an autorotation with normal forward speed compared with a vertical ?

Question 247-18 : Always lower always greater lower up to a certain speed but is then greater greater up to a certain speed but is then lower

In a normal forward autorotative descent if the collective is raised by a small ?

Question 247-19 : 1 decrease 2 decrease 1 decrease 2 increase 1 increase 2 decrease 1 increase 2 increase

One of the function of the anti torque device during an autorotation is ?

Question 247-20 : To prevent the fuselage rotating in the same direction as the main rotor blades non existent as the tail rotor is not required during autorotation to prevent the fuselage rotating in the opposite direction to the main rotor blades to control autorotation rpm

If an autorotative descent is commenced from a high altitude and collective ?

Question 247-21 : And rate of descent will decrease and rate of descent will increase will increase and rate of descent will decrease will decrease and rate of descent will increase

The required condition for the initiation of ground resonance is ?

Question 247-22 : A deliberate or unintentional oscillation of the helicopter in contact with or resting on the ground a moment produced by the horizontal component of total rotor thrust about the point of ground contact of the skid low rotor rpm during start up or shut down producing insufficient centrifugal force on the blades the helicopter c of g positioned outside the wheelbase coupled with a self generated rotor head vibration

The most likely causes of rotor head vibration are ?

Question 247-23 : Faulty drag dampers incorrect blade tracking and blades of unequal weight or balance ineffective droop stops faulty drag dampers and moisture ingestion in the blades faulty drag dampers incorrect tracking and inefficient flapping restrainers blades of unequal weight or balance faulty drag dampers and inoperative pitch operating arms

If ground resonance is encountered in a helicopter the correct recovery action ?

Question 247-24 : To take off if rotor rpm sufficient to shut down and apply rotor brake if rotor rpm insufficient to shut down immediately regardless of rotor rpm to apply pitch for take off immediately regardless of rotor rpm to increase rotor rpm to take off power and get airborne

Vortex ring settling with power will probably occur if power is applied when ?

Question 247-25 : 30 kts and the rate of descent is greater than 300 fpm 50 kts and the rate of descent is greater than 300 fpm 30 kts and the rate of descent is greater than 100 fpm 50 kts and the rate of descent is greater than 100 fpm

The loss of lift leading to retreating blade stall will commence ?

Question 247-26 : Near the tip mid way along the span at the root at the same indicated airspeed regardless of altitude temperature and all up weight of the helicopter

Autorotative moment of the aerodynamic forces ?

Question 247-27 : Drives the rotor during autorotation opposes the weight of a helicopter during autorotation is the resultant of the forces of gravity and inertia due to the forward speed during autorotation is the opposite torque required from the tail rotor to maintain direction during an autorotative descent

At a given power setting ground effect is most effective when hovering ?

Question 247-28 : Over a hard level surface over a disturbed water surface into a moderate wind over long grass

A fully articulated rotor permits the blades to ?

Question 247-29 : Flap drag and feather feather only flap and drag only feather and drag only

Should a helicopter suffer from retreating blade stall in flight to reduce the ?

Question 247-30 : The collective pitch should be lowered to decrease pitch power should be reduced and collective pitch increased at once to reduce speed the cyclic control should be pushed forward to increase speed the cyclic control should be pulled back to decrease speed in a flare manoeuvre

'dynamic roll over' may be caused by ?

Question 247-31 : An excessive rolling movement developing about a skid or wheel in contact with a slope or uneven ground excessive yaw pedal movements the torque effect of rapid acceleration of the main rotor excessive movement of the cyclic control in pitch only

A main rotor blade may be twisted along its span to ensure ?

Question 247-32 : A more desirable lift distribution that the angle of attack remains constant when the blade bends under the load that retreating blade stall occurs first at the tip that retreating blade stall occurs first at the root

The maximum speed during backwards is lower than in forward flight this is due ?

Question 247-33 : The reduced control range in the rearward direction and the directional stability of the airframe aerodynamic interference between the main and tail rotors the restricted clearance between the main and tail rotors the increased parasite drag when flying backwards

When in the hover movement of the collective lever upwards will change the ?

Question 247-34 : By an equal amount throughout 360 of rotation to prevent excessive coning of the blades independently as each blade passes the helicopter longitudinal axis about the flapping hinges

In a tail rotor asymmetry of lift ?

Question 247-35 : May be reduced by allowing blade flapping cannot occur since the relative airlow velocity is the same at any position cannot be reduced in any configuration and therefore has to be accepted is essential for the correct functioning of the helicopter

A helicopter having an anti clockwise rotating main rotor when seen from above ?

Question 247-36 : To the right to the right if the tail rotor is on the left of the aircraft and to the left if it is on the right in neither direction because transverse forces are in balance to the left

In a hingeless main rotor there are ?

Question 247-37 : Feathering bearing but no dragging or flapping hinges dragging and feathering hinges but no flapping hinges flapping and feathering hinges but no dragging hinges flapping hinges but no dragging or feathering hinges

In a shrouded tail rotor fenestron the blades ?

Question 247-38 : Respond to tail rotor collective pitch control respond to tail rotor cyclic and collective pitch control respond to tail rotor cyclic control are fully articulated

Ground resonance can be prevented from developing to a critical point if action ?

Question 247-39 : Applying collective pitch control and lifting off applying the rotor brake as rapidly as possible compensating for helicopter movement with cyclic control avoiding any control input until all vibration has ceased

The three main features which define the maximum speed of a helicopter are ?

Question 247-40 : Compressibility limit of advancing blade retreating blade stall and design limits of cyclic control runaway rotor rpm limit critical flapback speed and airflow reversal retreating blade stall blade sailing limit and tail rotor overspeed limit design limit of collective control compressibility limit of advancing blades and airflow reversal