FLIGHT CONTROL SYS

Question 1

Name the four types of mechanical compensation (control mixing) and the one type of electrical compensation.

Answer 1

Collective to yaw
Collective to lateral
Collective to longitudinal
Yaw to longitudinal

Collective / airspeed to yaw

Question 2

Collective to yaw (control mixing)

Answer 2

main rotor torque causes the nose of the aircraft to yaw to the right with increased collective

to compensate, the tail rotor thrust is increased

Question 3

Collective to lateral (control mixing)

Answer 3

the tractor tail rotor causes the helo to drift right with increased collective

to compensate, the rotor disc is tilted to the left

Question 4

Collective to longitudinal (control mixing)

Answer 4

rotor downwash on the stabilator causes the nose to pitch up and the helo to drift aft with increased collective

to compensate, the rotor disc is tilted forward

Question 5

Yaw to longitudinal (control mixing)

Answer 5

the tail rotors 2.5% lift factor causes the nose to pitch down and the helo to drift forward when left pedal is applied

to compensate, the rotor disc is tilted aft

Question 6

Collective / airspeed to yaw (control mixing)

Answer 6

because the tail pylon is a vertical airfoil, the nose will tend to yaw to the left as airspeed increases which means that less anti-torque is required

the trim will compensate by washing out pedal requirements as airspeed increases

Question 7

How are the cyclic, collective, and pedal flight control inputs routed to the rotor system?

Answer 7

routed aft and outboard of each pilot seat, vertically up each side of the aircraft, and are combined for each axis at the overhead torque shafts in the hydraulics bay.

the overhead torque shafts transfer inputs through the pilot assist servos and the mixing unit.

from the mixing unit, the FAL inputs are transferred to the swashplate assembly via the primary servos and the bridge assembly.

from the swashplate, the inputs move upward through the pitch control rods to the pitch change horns

Question 8

What type of system is our main rotor?

Answer 8

fully articulated system

Question 9

How is the swashplate assembly attached to the low pressure plate?

Answer 9

the rotating and stationary swashplate are attached to a low pressure plate via the rotating scissors

Question 10

The main rotor blades are attached to the rotor head via a _____ ______ ______.

Answer 10

hinged spindle assembly

Question 11

What enables the main rotor blades to flap, lead/lag, and move for pitch changes?

Answer 11

elastomeric bearings

Question 12

What prevents extremely high/low blade flapping at low Nr?

Answer 12

droop stops and flap restraints

Question 13

The main rotor blades have _______ swept tips to increase efficiency and ________ to extend their useful life.

Answer 13

20 degree, abrasion strips

Question 14

What type of system is our tail rotor?

Answer 14

crossbeam blade system

Question 15

How many degrees is our tail rotor canted?

Answer 15

20 degrees

Question 16

Explain the spring tension and centering spring feature in the tail rotor.

Answer 16

there are two spring cylinders connected to the quadrant that provide tension to the tail rotor cables.

the spring tension feature allows for a fail safe if one cable breaks whereas the centering spring allows for present spring-loaded position of the tail rotor in the event both cables fail.

either failure will trigger the [TAIL ROTOR QUADRANT] caution

Question 17

Explain the fly home capability of the tail rotor system.

Answer 17

if both tail rotor cables fail, the fixed tail rotor setting provides a fly home capability of balanced flight to a 19,500 lb. aircraft on a standard day at sea level at 25 or 145 kts.

Question 18

Which direction will the nose want to go in a cable failure at 100 kts in a 19,500lb. aircraft on a standard day?

Answer 18

Right

Question 19

How do the cable failure airspeeds change if the aircraft is heavier than 19,500lb.?

Answer 19

the airspeed range decreases, i.e. above 25kts and below 145kts