Utility System Flashcards
How many accumulators are there in the utility system?
5
APU start accum
APU start signal accum
Utility reservoir accum
Wheel/brake accum
Swivel lock accum
The Utility Hydraulic System supplied hydraulic power for non-flight essential hydraulic systems. The systems are?
a. Wheel Brakes
b. Power Steering
c. Swivel Locks
d. Centering Cams
e. Ramp Actuation Cylinders
f. Cargo Door Motor
g. Center Cargo Hook
h. Cargo/Rescue Winch
i. Engine Starters
j. Power Transfer Units
k. APU Start Circuit
Reservoir Cooler Fan goes on and off at what temps?
Thermostatically controlled
Temperature range 54°C to 63°C
What are the two controllable check valves on the utility system?
One directs the APU Start accumulator pressure to the subsystems for emergency operation
The other controllable check valve is in the bootstrap 79-TA-1313 accumulator line to maintain the pressure on the reservoir during APU Start.
What to remember when preflighting the hydraulic fill module or filling it in flight?
Do not allow fluid level to go below site glass, air will be induced
What PSI does the Utility reservoir cooler bypass at?
25psi
What are the two purposes of the bleed relief valve of the utility reservoir?
- Manually operated to bleed air from the reservoir.
- Protects the reservoir against over-pressurization.
Are the flight control coolers similar in operation to the utility cooler?
The utility reservoir/cooler is identical in operation to the No.1 and No.2 flight control hydraulic reservoir/coolers. The temperature sensor, thermal switch and the relief valve are interchangeable with the No. 1 and No.2 flight control hydraulic reservoir/coolers.
How do the PTU’s operate?
When Solenoid is open, pressure operate valve closes and removes pressure from system
Solenoid is open when #1 DC bus is online
Closed when no power to DC bus
Closed when you flip PTU switch (you must have DC power to flip switch)…this allows pressure to flow through POV and onto PTU motor.
Only 1 switch needs to be flipped to close solenoid at pressure control module…this allows pressure to flow to both PTU’s and continue to the motor via the opened solenoid of the chose system. You must electrically open up the other system at the motor pump with the switch: 1 solenoid on the PCM and 1 solenoid on each PTU.
What are pump fault lights associated with?
Associated with an increased flow rate within the case drain line (1gpm +/- .25).
What is the difference between a case drain and a seal drain?
A case drain is for the fluid that passes between the internal piston of the pump and the pump housing.
A seal drain allows for fluid leakage between the pump and the component it is bolted to (ex: transmission), to be drained from system.
