20 terms

AFAST-Helicopter Knowledge Section

Helicopter Knowledge Section of the AFAST
STUDY
PLAY
A lighted heliport may be identified by
(A) a flashing yellow light.
(B) a blue lighted square landing area.
(C) white and red lights.
(D) a green, yellow, and white rotating beacon.
(E) blue and red alternating flashes.
The correct answer is (D). The color combination of
green, yellow, and white flashed by beacons indicates
a lighted heliport.
The primary purpose of the tail rotor system is to
(A) assist in making a coordinated turn.
(B) maintain heading during forward flight.
(C) counteract the torque effect of the main rotor.
(D) provide additional thrust and lift.
(E) increase maximum speed.
The correct answer is (C). The auxiliary or tail rotor
is the anti-torque rotor that produces thrust in the
direction opposite to the torque reaction developed by
the main rotor.
During a hover, a helicopter tends to drift in the
direction of tail rotor thrust. This movement is called
(A) flapping.
(B) gyroscopic precession.
(C) transverse flow effect.
(D) translating tendency.
(E) Coriolis force.
The correct answer is (D). The entire helicopter has
a tendency to move in the direction of tail rotor thrust
when hovering. This movement is generally referred
to as translating tendency or drift.
The upward bending of the rotor blades resulting
from the combined forces of lift and centrifugal force
is known as
(A) translational lift.
(B) blade flapping.
(C) Coriolis effect.
(D) dissymmetry of lift.
(E) coning.
The correct answer is (E). The upward bending of
the rotor blades caused by the combined forces of lift
and centrifugal force is called coning.
In a helicopter, the center of gravity (CG) range is
usually located
(A) in front of the main rotor mast.
(B) in the rear of the main rotor mast.
(C) directly above the main fuel tank.
(D) directly below the main fuel tank.
(E) a short distance fore and aft of the main
rotor mast.
The correct answer is (E). The exact location and
length of the CG range is specified for each
helicopter, but it usually extends a short distance fore
and aft of the main rotor mast.
The lift differential that exists between the advancing
main rotor blade and the retreating main rotor blade
is known as
(A) Coriolis effect.
(B) dissymmetry of lift.
(C) translating tendency.
(D) translational lift.
(E) lift vector.
The correct answer is (B). Dissymmetry of lift is
created by horizontal flight or by wind during
hovering flight. It is the difference in lift (unequal
lift) across the rotor disc resulting from the difference
in the velocity of air over the advancing blade half of
the disc area and retreating blade half of the disc area.
Ground resonance is most likely to develop when
(A) there is a sudden change in blade velocity in the
plane of rotation.
(B) a series of shocks causes the rotor system to
become unbalanced.
(C) there is a combination of a decrease in the angle
of attack on the advancing blade and an increase
in the angle of attack on the retreating blade.
(D) initial ground contact is made with a combination
of high gross weight and low RPM.
(E) there is a defective clutch or missing or bent
fan blades in the helicopter engine.
The correct answer is (B). Ground resonance may
develop when a series of shocks causes the rotor head
to become unbalanced. When one landing gear of the
helicopter strikes the surface first, a shock is
transmitted through the fuselage to the rotor. When
one of the other landing gears strikes, the unbalance
can be aggravated and become even greater. This
establishes a resonance, which sets up a pendulumlike
oscillation of the fuselage—a severe wobbling or
shaking.
The proper action to initiate a quick stop is to
(A) increase the RPM.
(B) decrease the RPM.
(C) raise the collective pitch.
(D) lower collective pitch and apply forward cyclic.
(E) lower collective pitch and apply aft cyclic.
The correct answer is (E). Rapid deceleration or
quick stop is initiated by applying aft cyclic to reduce
forward speed and lowering the collective pitch to
counteract climbing.
Takeoff from a slope in a helicopter with skid-type
landing gear is normally accomplished by
(A) simultaneously applying collective pitch and
downslope cyclic control.
(B) bringing the helicopter to a level attitude before
completely leaving the ground.
(C) making a downslope running takeoff if the surface
is smooth.
(D) rapidly increasing collective pitch and upslope
cyclic controls to avoid sliding downslope.
(E) turning the tail upslope, when moving away
from the slope, to reduce the danger of the tail
rotor striking the surface.
The correct answer is (B). For slope takeoff, first
obtain takeoff RPM and move the cyclic stick so that
the rotor rotation is parallel to the true horizon rather
than the slope. Apply up-collective pitch and apply
pedal to maintain heading. As the downslope skid
rises and the helicopter approaches a level altitude,
move the cyclic stick back to the neutral position and
take the helicopter straight up to a hover before
moving away from the slope. The tail should not be
turned upslope because of the danger of the tail rotor
striking the surface.
The proper procedure for a slope landing in a helicopter
with skid-type landing gear is
(A) to use maximum RPM and maximum manifold
pressure.
(B) when parallel to the slope, slowly lower the
downslope skid to the ground prior to lowering
the upslope skid.
(C) if the slope is 10 degrees or less, the landing
should be made perpendicular to the slope.
(D) when parallel to the slope, slowly lower the
upslope skid to the ground prior to lowering the
downslope skid.
(E) if the slope is 10 degrees or less, the landing
should be downslope or downhill.
The correct answer is (D). The helicopter should be
landed on a cross-slope rather than on either an
upslope or downslope. As the upslope skid touches
the ground, the pilot should apply the cyclic stick in
the direction of the slope. This will hold the skid
against the slope while the downslope skid continues
to be let down with the collective pitch.
Density altitude refers to a theoretical air density that
exists under standard conditions at a given altitude.
Standard conditions at sea level are
(A) 29.92 in. of Hg (inches of mercury) and 15°C.
(B) 29.92 in. of Hg (inches of mercury) and 20°C.
(C) 29.92 in. of Hg (inches of mercury) and 30°C.
(D) 14.96 in. of Hg (inches of mercury) and 15°C.
(E) 14.96 in. of Hg (inches of mercury) and 30°C.
The correct answer is (A). Standard conditions at
sea level are: Atmospheric pressure: 29.92 in. of Hg
(inches of mercury); Temperature: 59°F. (15°C.)
A helicopter pilot should consider using a running
takeoff
(A) if the helicopter cannot be lifted vertically.
(B) when a normal climb speed is assured between
10 and 20 feet.
(C) when power is insufficient to hover at a very
low altitude.
(D) when the additional airspeed can be quickly
converted to altitude.
(E) when gross weight or density altitude prevents
a sustained hover at normal hovering altitude.
The correct answer is (E). A running takeoff is used
when conditions of load and/or density altitude
prevent a sustained hover at normal hovering altitude.
It is often referred to as a high-altitude takeoff. A
running takeoff may be accomplished safely only if
surface area of sufficient length and smoothness is
available and if no barriers exist in the flight-path to
interfere with a shallow climb.
Foot pedals in the helicopter cockpit enable the pilot to
(A) control torque effect.
(B) regulate flight speed.
(C) regulate rate of climb.
(D) regulate rate of descent.
(E) stabilize rotor RPM.
The correct answer is (A). Foot pedals in the cockpit
permit the pilot to increase or decrease tail-rotor
thrust, as needed, to neutralize torque effect.
If the helicopter is moving forward, the advancing
blade will be in the
(A) forward half of the rotor disc.
(B) left half of the rotor disc.
(C) rear half of the rotor disc.
(D) right half of the rotor disc.
(E) It cannot be estimated.
The correct answer is (D). With a single main rotor
rotating in a counterclockwise direction, the advancing
blade will be in the right half of the rotor disc
during forward flight.
The method of control by which the pitch of all main
rotor blades is varied equally and simultaneously is the
(A) auxiliary rotor control.
(B) collective pitch control.
(C) cyclic pitch control.
(D) tail rotor control.
(E) throttle control.
The correct answer is (B). The collective pitch
control lever changes the pitch angle of the main rotor
blades simultaneously and equally.
The combination of factors that will reduce helicopter
performance the most is
(A) low altitude, low temperature, and low humidity.
(B) low altitude, high temperature, and low humidity.
(C) low altitude, low temperature, and high humidity.
(D) high altitude, low temperature, and low humidity.
(E) high altitude, high temperature, and high
humidity.
The correct answer is (E). High altitude, high
temperature, and high moisture content contribute to
a high density altitude condition that lessens
helicopter performance.
The most favorable conditions for helicopter performance
are the combination of
(A) low-density altitude, light gross weight, and
moderate to strong winds.
(B) high-density altitude, heavy gross weight, and
calm or no wind.
(C) low-density altitude, light gross weight, and
calm or no wind.
(D) high-density altitude, light gross weight, and
moderate to strong winds.
(E) low-density altitude, heavy gross weight, and
moderate to strong winds.
The correct answer is (A). The most favorable
conditions for helicopter performance are the combination
of a low-density altitude, light gross weight,
and moderate to strong winds. The most adverse
conditions are the combination of a high-density
altitude, heavy gross weight, and calm or no wind.
Any other combination of density altitude, gross
weight, and wind conditions fall somewhere between
the most adverse conditions and the most favorable
conditions.
Picture Not Yet Available
The correct answer is (B). The acute angle between
the chord line of an airfoil and the relative wind is
called the angle of attack.
During surface taxiing, the helicopter pilot should use
the pedals to maintain heading and the cyclic to
maintain
(A) ground track.
(B) proper RPM.
(C) starting.
(D) stopping.
(E) All of the above
The correct answer is (A). The collective pitch
controls starting, stopping, and rate of speed. Pedals
are used to maintain heading and the cyclic is used to
maintain ground track.
The thinner air of higher altitudes causes the airspeed
indicator to read "too low." An indicated airspeed of
80 mph at 5,000 feet is actually a true airspeed of
approximately
(A) 72 mph.
(B) 88 mph.
(C) 96 mph.
(D) 104 mph.
(E) 112 mph.
The correct answer is (B). True airspeed may be
roughly computed by adding to the indicated
airspeed, two percent of the indicated airspeed for
each 1,000 feet of altitude above sea level.