Hydraulics / Flight Controls Flashcards
Where are the servoactuators?
Longitudinal: #2 side
Collective: middle
Lateral: #1 side
What do you loose if there is a failure in the primary hydraulic system?
BUCS & FMC
What drives the hydraulic pumps?
The main transmission AGB drives the hydraulic pump. During normal aircraft operations, the aircraft engines drive the transmission.
What does the utility hydraulic system provide pressure to?
The Utility side of the flight control servoactuators, tail wheel lock actuator, Area Weapon System (AWS) azimuth drive motor, AWS elevation actuator, ammunition carrier drive motor, and the four pylons.
It also provides a source of stored, high-pressure hydraulic fluid for rotor brake operation, APU starter motor operation, and emergency operation of the flight control servoactuators.
How does emergency hydraulics work?
The low-level switch provides a signal to the SP when the oil level has dropped to a minimum operating level. It also provides a 28 Vdc signal to actuate the emergency hydraulic shutoff valve, shutting off fluid flow to the tail wheel unlock actuator and the Utility side of the tail rotor servo.
The low-level valve, when moved by the reservoir piston, prevents system operating pressure (3000 psi) from being routed to the auxiliary isolation valve, allowing it to close and shut off pressurized fluid to the auxiliary components.
The auxiliary isolation valve automatically eliminates fluid pressure to the following auxiliary components during an emergency (loss of system pump pressure) or low fluid level conditions in the reservoir: AWS elevation actuator and azimuth drive motor, Ammunition carrier drive motor, and Pylons.
The FMC provides rate dampening, command augmentation, attitude and altitude hold within what authority of the system?
+/- 10% all axis except forward pitch which is 20%
In automatic stabilator mode, automatic scheduling is provided in accordance with what 3 items?
Collective position
Airspeed
Pitch rate
What is the trailing edge ranges for the different modes of stabilator operation?
Auto: -5 deg up to +25 deg trailing edge down
Manual: -10 deg up to +35 deg trailing edge down
NOE: 25 deg trailing edge down up to 80 knots
At what speed will turn coordination automatically be provided by the stabilization system?
40 knots
When can position hold be engaged?
Below 5 knots ground speed
Velocity hold can be engaged at ground speeds between ____________:
5 - 40 knots (30 knots when decelerating in attitude hold mode)
Vertical velocity limits for attitude hold mode engagement:
<400 fpm at cruise
When will altitude hold mode automatically disengage?
Collective displaced more than 1/2 inch from reference position
Nr >104, or Nr <97
Either engine exceeds 100% torque
TGT exceeds 866 Celsius
When will radar altitude hold be engaged?
0 - 40 knots ground speed and 0 - 1428 AGL
What 2 systems are required for BUCS to work?
Primary hydraulics and FMC
BUCS: In a jam, the FMC will wash in full authority in ________
3 seconds
BUCS: In a severance, the FMC will wash in full authority in ________
1 second
The utility hydraulic system provides power to:
Utility side of all 4 servos Area weapon turret drive Ammunition handling system External stores elevation actuator - Emergency hydraulics APU start Rotor brake
Flight control loss will occur when the emergency accumulator drops to _______.
1650 psi
How long will it take for emergency hydraulics to bleed off?
About 6 minutes
Moving the controls at a 1 Hz rate may reduce this to as little as 30 - 41 seconds
How much pressure is applied to the rotor brake when set to brake and lock?
Brake: 337 psi
Lock: 3000 psi
