SIFT Complete Aviation Knowledge
As air becomes less dense, it causes the following change in force:
A reduction in power at the engine intakes
A helicopter center of gravity is usually located
A short distance fore and aft of the main rotor mast
What is true about induced drag?
It always pushes in a direction opposite of lift
Lowering the collective while the helicopter is flying straight and level will have what effect, assuming everything else remains constant?
It will cause the nose to pitch down, the helicopter's airspeed to increase, and will produce left yaw
What maneuver should be avoided when flying with a heavy load?
Large angle banking turns
Which direction(s) are the anti-torque pedals designed to move the nose?
Left and right
If the cyclic pitch control is pushed to the left, which way will the rotor disk tip and which way will the helicopter move?
Left; left
The combination of factors that reduce helicopter performance the most is
Low density altitude, light gross weight, and calm or no wind
Hovering steps
****
AH-64
-Apache -Attack
UH-60
-Blackhawk -Utility. Troop transport and sling loads operations
CH-47
-Chinook -Cargo and troop transport
UH-72
-Lakota -Utility
MH-6
-Little Bird -Observation
Maximum ground effect occurs during a hover up to a height equal to ___ percent of the main rotor's diameter:
100
Because of gyroscopic precession, if a wind gust applies a downward force on the left side of a helicopter's main rotor disk as it spins clockwise (as viewed from above), the movement response occurs at the __ o'clock position:
12
Helicopters experience effective translational lift while transitioning to forward flight at approximately __ to __ knots:
16; 24
A helicopter begins a descent at 300 feet above the ground, with the intent to lower to 200 feet above the ground. The pilot begins the descent at a steady rate of 400 FPM. At what altitude should he begin leveling out the helicopter?
240 feet
Helicopters typically have between __ and __ main rotor blade(s):
2; 6
Which type of climb produces the most altitude in a given distance?
A best angle of climb
What would make a good reference point when attempting to hover?
A building
Depending on the type of helicopter, main rotor system components can include:
A stabilizer bar, upper and lower swashplates, counterweights, pitch horns, teeter or coning hinges, blade grips, pitch and scissor links, and control rods
Multi-engine helicopters have:
A throttle lever for each engine
A helicopter is:
A type of rotorcraft
What item was developed to reduce compass reading errors?
A vertical card compass
Which instrument indicates if an aircraft is in a climb, in a descent, or in a level flight?
A vertical speed indicator
What do these acronyms stand for? A. AGW/AUW B. MLW C. MRW D. MTOW E. OEW
AGW aka AUW: aircraft gross weight, aka all-up weight MLW: maximum landing weight. MRW: maximum ramp weight. MTOW: maximum takeoff weight. OEW: operating empty weight.
At what pace should a helicopter in forward flight move?
About as fast as a brisk walk
If magnetic north is a positive 15-degree variation (west) from true north, to convert true north to magnetic north when flying eastbound, what is the adjustment a pilot must make to the magnetic compass?
Add 15 degrees
What is a complication unique to sideward hovering flight, as opposed to forward and rearward flight?
Additional pressure needed on the anti-torque pedals to deal with the weathervane
What is the preferred method of ground movement for helicopters on airports?
Air taxi
The angle of attack (AOA) is the angle between the
Airfoil chord line and the resultant relative wind
What factors affect the lift produced by spinning rotor blades:
Airfoil coefficient of lift, air density, and blade area.
In the case of helicopters, lift is produced by ________ moving through the air at a speed sufficient to create _______________:
Airfoils; a pressure differential
Which pilot-static instrument makes use of both pitot and static pressure?
Airspeed indicator
A helicopter's cyclic control is a mechanical linkage used to change the pitch of the main rotor blades:
All at the same time
Where there is too much lift, the main rotor blades will:
Flap
What would NOT be included in the maximum internal weight?
An object supported by a winch
A pilot is performing a straight and level flight when he realizes that the helicopter has drifted to the left of the intended path. What should he do?
Apply rightward pressure to the cyclic
When climbing at cruising speed, in addition to raising the collective, the rate of climb can be increased by which actions?
Applying rearward cyclic pressure to reduce airspeed
Which term is used to describe the weight of an aircraft, including all hydraulic and oil systems, full, trapped and unusable fuel, and all fixed equipment?
Basic empty weight
Ground effect is most likely to result in which problem?
Becoming airborne before reaching appropriate takeoff speed
The atmospheric pressure on the top surface of an airfoil decreases as the velocity of the air moving past it increases. This is an example of
Bernoulli's principle
A pilot wishes to reposition the helicopter while hovering to get to a designated runway for a surface takeoff. After performing a hovering turn to set her bearing properly, the pilot needs to move the helicopter forward. To do this, she should do what?
Briefly apply pressure to the cyclic, then release the cyclic
The angle between the ________ of a rotor blade and its direction of motion relative to the ________ is the angle of attack (AOA), which is ________ angle.:
Chord line; air; an aerodynamic
The angle of incidence is between the ________ line of each blade and the rotor system's ________:
Chord; plane of rotation
What effect is principally used to counteract main rotor torque with the NOTAR system used on the MD-520N and MD-900 helicopters?
Coanda effect
The method of control by which the pitch of all main rotor blades is varied equally and simultaneously is the
Collective control
While performing a banking left turn, the pilot notices that the helicopter has begun to skid. What can he do to get out of this?
Decrease pressure on the left anti-torque pedal or increase pressure on the right anti-torque pedal
What are the dangers of overloading a helicopter?
Decreased performance and structural damage
If sufficient takeoff power is in doubt, what should the pilot do?
Delay the takeoff until the aircraft is lighter and wait until the density altitude has decreased
When performing an air taxi, what should be avoided?
Flying in the shaded area of the height-velocity diagram, flying over other aircraft, vehicles, and personnel, and flying in crosswind conditions
The lift differential that exists between the advancing main rotor blade and the retreating main rotor blade is known as
Dissymmetry of lift
What are the three regions of a rotor in autorotation?
Driven, driving, and stall
The _______ region is normally between a blade's _______ and _______ regions:
Driving; stall; driven
How would a pilot recognize the onset of transverse flow effect?
During takeoff, a vibration and a right rolling motion occurs as the aircraft accelerates through 10 to 20 knots
When a helicopter engine ________, a clutch mechanism called a __________________:
Fails; freewheeling unit automatically disconnects the engine from the main rotor, allowing it to spin freely
If the helicopter is nose down while attempting to hover, and there are no winds, then it most likely has which of the following?
Front-loaded center of gravity
What is the load factor of a 2000-pound helicopter that is currently experiencing an effective load of 4000 pounds?
G=L1/L0. Using 4000 as L1 and 2000 as L0, the result would be G=4000/2000, which equals 2.
When generating lift, what should the pressure below the airfoil be in relation to the pressure above the airfoil?
Greater than it
During a hover, a helicopter tends to drift to the right. To compensate for this effect, some helicopters
Have the rotor mast rigged to the left side
Which of the following should not need to be maintained while performing a hovering turn?
Heading
A helicopter pilot is attempting to take off when she notices that the helicopter's nose tilts down after leaving the ground. What is most likely the problem?
Imbalanced center of gravity
On the advancing rotor blade, lift ________ and the blade __________________:
Increases; moves upward
If there is no increase in thrust, which action would result in an ultimate stall?
Increasing pitch
What would increase the torque on the helicopter?
Increasing the throttle
Vortices produced by spinning rotor blades create:
Induced drag
Which type of drag is caused by production of lift?
Induced drag
What is true regarding the governor?
It adjusts the throttle as needed, it uses an electronic sensor, it regulates the power to maintain RPM, and it requires almost no manual control
What effect does the cyclic control have on the rotor system?
It alters the pitch of the main rotor blades individually and cyclically
What action should a helicopter pilot take if engine failure occurs at altitude?
Lower the collective pitch control to maintain rotor RPM
For helicopters with a main rotor disk that spins counter-clockwise, the ________ airflow speed happens when each blade reaches the ________ position:
Maximum; three o'clock (right)
Helicopter turbine engines produce _________ thrust per pound than piston engines:
More
The driven region is ________ the blade tips and normally __ percent of the radius:
Nearest; 30
Many helicopters have a horizontal stabilizer located:
On the tail boom
A pilot can worsen a helicopter's pendular action by:
Over-controlling the aircraft
Thrust acts ________ to the aircraft's ________________________:
Parallel; longitudinal axis
Which type or types of drag increase as the speed increases?
Parasitic drag and profile drag
How would a high-density altitude affect the performance of a helicopter?
Performance would be decreased due to low value of the air density
Risk management is composed of which four risk elements?
Pilot, aircraft, environment, and external pressures
The degree of movement of an aircraft around its lateral axis is known as
Pitch
What three conditions are necessary for a helicopter to be in danger of a dynamic rollover?
Pivot point, rolling motion, and exceeding critical angle
Although both parasitic drag and profile drag increase as speed increases, what is the difference between the two?
Profile drag starts out as more significant, but parasitic drag becomes more significant at higher speeds
Centrifugal force ________ spinning helicopter main rotor blades ________.
Pulls; outward
When the pilot wants the helicopter's nose to move left or right, he or she:
Pushes on the corresponding pedal
What decreases upon an increase to the collective pitch controller?
RPM
What does not need to be checked before beginning a normal takeoff from hover?
RPM
A pilot has successfully identified that the helicopter has an aft-loaded center of balance. What method would correct this?
Removing cargo from the back of the helicopter
Lift differential (the result of one rotor losing lift because of an advancing aircraft's forward airspeed) that exists between the advancing main rotor and the retreating rotor blade is known as
Retreating blade stall
What is resultant relative wind?
Rotational relative wind modified by induced flow
What aerodynamic condition can occur when a helicopter is descending at greater than 300 fpm, has 20 to 100 percent power applied, and an airspeed less than effective translational lift?
Settling with power
When an aircraft is approaching to land, the leading and trailing edges of its flaps are extended to create the following force (s).
Since airspeed is decreased, maximum lift is required plus high drag to slow the aircraft.
When performing a vertical takeoff to a hover, what should be done if the heading begins to change?
Slowly adjust the anti-torque pedals
Wheels on ______ types of helicopters are ________:
Some; retractable
A helicopter performing a takeoff from hover has just entered effective translational lift and has begun to increase the collective. Which step of the takeoff is the helicopter currently in?
Step three
What type of helicopter design uses a ducted fan in place of a tail rotor to cancel torque effect?
The NOTAR design
Translational lift is
The additional lift gained when the helicopter leaves the disturbed air from its rotor downwash
What control is a rate-controlled instrument?
The anti-torque pedals
After achieving the desired altitude, the pilot decides to perform a takeoff from a hover and applies forward pressure on the cyclic to begin forward movement. Which control/s will he need to use while doing so, assuming ideal conditions?
The collective, anti-torque pedals, and the throttle
While hovering, a pilot wishes to increase her altitude, so she uses the collective. Which control will the pilot NOT need to use while doing so, assuming ideal conditions?
The cyclic
In a straight-and-level flight, which control is primarily used to increase airspeed?
The cyclic pitch control
A pilot notices that as the helicopter flies, the nose slowly drops. The cyclic is in its neutral position. What is most likely the cause of this?
The fuel in the rear of the helicopter is being used up, slowly shifting the center of balance forward
When a pilot banks a helicopter, causing it to turn, ___________________________:
The machine's weight increases
When the pilot pushes the cyclic forward:
The main rotor disk tilts forward
When raised elevators push down on the tail of an aircraft, what effect does that have on the aircraft?
The nose of the aircraft rises
What isn't included in a helicopter's base empty weight?
The pilot
Which is true of helicopter performance in ground effect (IGE)?
The rotor system becomes more efficient since the ground interferes with the circulation pattern, and less power is required to hover
Which aircraft component(s) affect yaw?
The rudder
Newton's Third Law of Motion applies to helicopters because:
The spinning main rotor makes the aircraft try to spin in the opposite direction
What part of a rotary-wing aircraft makes directional control possible?
The swashplate
What gives the pilot control over the yaw axis of the aircraft?
The tail rotor pedals
What flight control maintains the engine within optimal flight parameters?
The throttle
What happens when a helicopter's main rotor blades spin rapidly?
The upper and lower sides of each blade experience a difference in pressure.
What influences the G load?
The weather and air density
The function of the flybar is:
To decrease crosswind thrust on the blades and enhance flight stability by keeping the bar stable as the rotor spins
The purpose of the tail rotor is:
To produce an anti-torque force acting perpendicular to the helicopter's longitudinal axis
When plotted on a graph, L/DMAX is the point where the helicopter's _____________.
Total lift-to-drag ratio is the greatest
From a physics perspective, the ______ force is deemed to act through a helicopter's __________:
Total weight; center of gravity
What causes a rotary-wing aircraft to drift laterally due to tail rotor thrust?
Translating tendency
What are the four fundamental maneuvers?
Turning, straight and level flight, climbing, and descending
If left uncorrected, greater lift produced by the advancing side of the rotor disk compared to the lift created by the disk's retreating side could make the helicopter ___________.
Uncontrollable
During an autorotation in forward flight, the rotor disk takes in ________ air and the driven, driving, and stall regions of each blade move ________ along its length (span), but only on the ________ side of the disk:
Upward flowing; outboard; retreating
Which aerodynamic force(s) must a rotary-wing aircraft balance in order to hover?
Weight, lift, thrust, and drag
When performing a hovering turn on a windy day, at what point is weathervane most likely to cause problems?
When the helicopter's heading is with the wind
What does not affect density altitude?
Wind velocity
Night Myopia
lightly nearsighted individuals viewing blue-green light may experience blurred vision
