NATOPS APU Flashcards
What types of APUs do we have?
Turbomach/Sundstrand APU
Garret APU
What does the APU do?
It provides pneumatic power for starting the engines and operating the Environmental Control System (ECS)
What does the APU consist of?
It is a gas turbine engine with a power section, a reduction gearbox, appropriate controls, and accessories.
Fuel consumption at rated power is ___.
150 lbs per hour
Operations of the APU in flight (should/shall) be limited to ___.
Shall
essential operations only
What are the acceptable in-flight uses of the APU?
- EPs
- Single-engine training
- practice autorotations
- powering the ECS during extreme temperature operations
What are the APU system accessories?
- prime/boost pump
- hydraulic accumulator (with hand pump)
- hydraulic starter
- ac generator
What does the prime boost pump do?
Used to prime the engine or APU fuel lines.
Also provides fuel under pressure to the APU during starting and operations at pressure altitudes above 8000 ft
What does the hydraulic accumulator do?
provides the hydraulic pressure for driving the APU starter
What is the minimum accumulator pressure required for starting the APU?
2650 psi
With AC power available, the accumulator is charged by the ____.
backup hydraulic pump
What is the APU controlled and monitored by?
Electronic Sequence Unit (ESU) or Digital Electronic Sequence Unit (DESU)
Will automatically shut down the APU if a start sequence fails or a monitored parameter is exceeded during operation (exception of APU OIL TEMP HI)
The DESU for the Turbomach/Sundstrand APU has the added capability to control what?
APU overtemperatures by regulating the main fuel valve and start bypass valve
What does APU FAIL mean?
APU has failed due to:
- High/Low Ng
- High/Low TGT
- Low Oil Pressure
- Start sequence failure
Where is fuel supplied from for the APU?
The right fuel cell by the prime/boost pump