SIFT Army Aviation Information Questions and Answers — Questions and Answers
Question 1: Which of the following U.S. Army helicopter designations correctly identifies an attack helicopter?
- CH-47
- UH-60
- AH-64 (Correct answer)
- OH-58
Correct answer: AH-64
In the U.S. military aircraft designation system, the 'A' in 'AH' stands for Attack. The AH-64 Apache is the Army's primary attack helicopter. 'CH' stands for Cargo Helicopter (e.g., Chinook), 'UH' for Utility Helicopter (e.g., Black Hawk), and 'OH' for Observation Helicopter (e.g., Kiowa).
Question 2: A pilot is flying a single-rotor helicopter in forward flight. The phenomenon where the advancing rotor blade generates more lift than the retreating blade is known as:
- Translational Lift
- Autorotation
- Dissymmetry of Lift (Correct answer)
- Coriolis Effect
Correct answer: Dissymmetry of Lift
Dissymmetry of lift is the unequal lift between the advancing and retreating halves of the rotor disc in forward flight. The advancing blade experiences higher airspeed (rotational speed + forward speed), generating more lift, while the retreating blade experiences lower airspeed (rotational speed - forward speed), generating less lift.
Question 3: In the event of a complete engine failure in a helicopter, the procedure that allows a pilot to safely land the aircraft by using the upward flow of air to keep the main rotor spinning is called:
- Flaring
- Gliding
- Autorotation (Correct answer)
- Collective Pitch Dump
Correct answer: Autorotation
Autorotation is a state of flight where the main rotor system is turned by the action of air moving up through the rotor, rather than by engine power. This allows a pilot to maintain rotor RPM and make a controlled landing after an engine failure.
Question 4: A pilot flying at 14,000 feet without supplemental oxygen begins to experience a sense of euphoria, impaired judgment, and drowsiness. What aeromedical condition is the pilot most likely experiencing?
- Hypemic Hypoxia
- Stagnant Hypoxia
- Histotoxic Hypoxia
- Hypoxic Hypoxia (Correct answer)
Correct answer: Hypoxic Hypoxia
Hypoxic hypoxia, also known as altitude hypoxia, results from insufficient oxygen available to the body due to the lower partial pressure of oxygen at high altitudes. Significant effects, including impaired judgment, drowsiness, and euphoria, typically begin between 12,000 and 15,000 feet.
Question 5: Which primary flight control in a helicopter is used to change the pitch of the main rotor blades collectively, or all at the same time, causing the aircraft to increase or decrease its altitude?
- Cyclic
- Anti-torque pedals
- Collective (Correct answer)
- Throttle
Correct answer: Collective
The collective pitch control (or collective) is used to make simultaneous changes to the pitch angle of all main rotor blades. Raising the collective increases the blade pitch angle, which increases lift and causes the helicopter to climb. Lowering it decreases the pitch angle and causes the helicopter to descend.
Question 6: During a pre-flight inspection of a UH-60 Black Hawk, a crew chief notices that the main rotor blades can flap and lead/lag. This design feature is essential to compensate for which aerodynamic principle in forward flight?
- Translational Thrust
- Dissymmetry of Lift (Correct answer)
- Ground Effect
- Effective Translational Lift
Correct answer: Dissymmetry of Lift
Blade flapping is a primary method of compensating for dissymmetry of lift. The advancing blade, which produces more lift, flaps upward, decreasing its angle of attack. The retreating blade flaps downward, increasing its angle of attack. This action equalizes lift across the rotor disc.
SIFT Army Aviation Information Questions and Answers
Which of the following U.S.
Army helicopter designations correctly identifies an attack helicopter?