Hydraulics/Flight Controls Flashcards
What does the utility hydraulic system power?
Wing flaps Main landing gear Nose landing gear Normal brakes Nosewheel steering Aerial refueling reels Half of the aileron, rudder, and elevator control boost
What does the booster hydraulic system power?
Half of the flight control boost system
What does the auxiliary hydraulic system power?
ramp and cargo door emergency brakes emergency nose landing gear extension (AR system in case of utility failure)
How is the auxiliary system connected to the utility system on the ground?
ground test valve
Utility system reservoir
5.5 gallons
Booster system reservoir
3.1 gallons
Describe the utility/booster system reservoirs
non-pressurized gravity-fed
Suction boost pump pressures
0-20 gallons/min 70-90 psi
What are the engine-driven hydraulic pumps rated at?
3000 psi
The flow capacity of each engine-driven hydraulic pump depends on what?
engine RPM
When do the pressure relief valves open in the hydraulic system?
3450 psi and reset at 3100 psi they bypass 23 gallons/min when fully open
Where is the hydraulic ground test valve located?
aft of the left main landing gear wheelwell
What is the hydraulic ground test valve used for?
allows the aux hyd system to be tied to the utility hyd system ground maintenance and operational checkout of the utility hydraulic system
Why are the suction boost pumps turn on prior to starting engines?
To prevent cavitation
What utility hydraulic system pressure triggers the ACAWS caution UTIL SYS PRESS HI?
3450 psi
When the FIRE handle is pulled, which valves in the hydraulic systems are shut off?
the suction line shutoff valve the pressure line shutoff valve
Auxiliary hydraulic reservoir
5.3 gallons
How is the auxiliary hydraulic pump driven?
electrically-driven
Where can we read auxiliary hydraulic pressure at all times?
direct-reading pressure indicator
What is the benefit of the ground test valve in the hydraulic system?
eliminates the need for engine operation normally required to supply utility hydraulic system pressure
How are the flight control surfaces moved?
by hydraulic booster assemblies connected through a series of cables, pulleys, and torque tubes.
What does the aileron diverter valve do?
provides improved handling qualities at speeds below 270 kts when the autopilot is not engaged directs either low limit or high limit booster and utility hyd pressure to the aileron booster assembly
What is the difference between the left and right aileron trim tabs?
left - moved by an electrical actuator right - fixed in place and only adjustable while the a/c is on the ground
What system controls the elevator auto trim system?
the flap system
What physically moves the elevator trim tabs?
mechanical jackscrews (which in turn are connected to an electric motor via a flex drive cable)
ADV system What happens to pressure once airspeed increases beyond 270 kts?
reduced until airspeed is once again less than 265 kts
What are the conditions that allow the MCs to activate the Aileron Diverter Valve?
lateral autopilot disengaged airspeed less than 270 hyd system px is within limits aileron system px transducers have not failed prop speed of two cross-side engines is greater than 80 percent
When you move the aileron trim tab to the left, what direction does the trim tab move?
moves the left hand trim tab DOWN which forces the left aileron up and lowers the left wing
When you move the aileron trim tab to the right, what direction does the trim tab move?
moves the left hand trim tab UP which forces the left aileron down and lowers the right wing
When you move the rudder trim tab to the left, what direction does the trim tab move?
to the right - this forces the rudder to the left
When you move the elevator trim tab to NOSE DOWN, what direction does the trim tab move?
up - forcing the elevators down and pitching the nose down
Describe the flaps
Fowler high-lift type (4 flaps total) flap motion is a combination of an aft movement to increase wing area and a downward tilting movement to alter the airfoil section to increase lift and drag
What mechanically raises and lowers the flaps?
8 jackscrews (2 in each flap)
What holds the flaps in the selected position and prevents movements by aerodynamic loads?
a spring-loaded flap brake
How does hydraulic pressure raise and lower the flaps?
Hydraulic pressure goes to the flap drive motor Flap drive motor provides torque to the flap drive gearbox
What component prevents movement of the flaps when an asymmetric flap condition is sensed?
emergency flap brake
Which component drives the flap travel through both hydraulic and mechanical action?
flap drive gearbox
When will the landing gear warning audio go off?
When flap lever is set to 70 percent or more with refueling pods NOT attached When flap lever is set to 80 percent or more with refueling pods attached and with landing gear not down and locked
When will the defensive system pylon chaff dispensers be disabled?
When flaps are extended greater than 15 percent
Describe how the flaps move.
Flap lever -> moves control cables -> sets switch plate which sends an electrical signal to wing flap selector valve -> directs hyd pressure to flap motor flap motor drives flap drive gearbox which spins the torque tubes -> torque tubes spin the 90 degree gearboxes which turn the jackscrews
What are the two basic reasons that we could have a flap failure?
electrically and hydraulically
What may result from pressing the manual reset on the emergency flap brake valve while the aircraft is in flight?
asymmetrical condition
What do the brake fuses do?
prevent excessive hydraulic fluid from escaping the brake system in the even of a brake line failure
How much brake fluid can escape the system before the brake fuse closes?
approx. 10 cubic inches
If emergency brakes are selected, what system is inoperative?
anti-skid system
What type of wheel brakes are installed on the aircraft?
hydraulically operated multiple disk
How is the anti-skid system activated?
anti-skid system provides touchdown protection, preventing brake application, until a wheel spin-up or WOW signal from either landing gear is sensed
What prevents the MLG from moving in the event of a hydraulic pressure loss?
an uplock brake
What serve as downlocks and prevent the MLG from retracting?
friction washers
What is the purpose of the nose landing gear pin when its installed?
prevents the release of the internal downlock and accidental retraction of the NLG
When the landing gear is NOT in the down and locked postion, when will the landing gear aural warning sound?
when power levers are within 5 degrees of FLT IDLE and the aircraft is below 1500 ft AGL (can be hushed) when extending the flaps more than 70 percent without refueling pods or 80 percent with refueling pods (cannot be hushed)
What does the Ground Beta Enable Valve do?
removes the hydraulic low pitch stop (13.0 +/-2 degrees) and isolates the OSG during ground beta operations to prevent it from reacting to overspeed transients.
