APU Flashcards
(33 cards)
What information should be entered on the −13 if the APU ON caution light fails to come on?
Record the BITE information from the ESU
The APU switch should be place to OFF if the APU fails to start or automatically shuts down. When this happens where should the battery switch be positioned?
Leave the battery switch on.
What action should you take if the UTIL HYD SYS caution light has not gone out within 30 seconds after the APU ON caution light comes on?
Place the APU switch to OFF position.
What 2 components are driven by the APU?
APU motor/pump, and APU generator
Control and monitoring of the APU is accomplished through what components.
The ESU.
What restriction is placed on APU operation during flight?
Emergencies only.
How long do you delay in the RUN position before going to START?
5 seconds.
What does the APU ON caution light indicate?
APU is operating properly.
How long must the APU switch be held at the START position during the start procedure?
2 seconds.
What is the maximum tail wind for starting the APU?
25 Knots.
After the APU control caution light comes on, how long may the utility Hydraulic caution capsule remain on?
30 seconds.
When the APU is shutdown, how long should you wait before attempting a restart?
1 minute.
How many horsepower is the APU
Max rating 95 SHP
Fuel consumption of APU
89-115 pounds per hour out of left main tank
Where does electrical power come from to control apu operations
Normally, electrical power to control apu operation is from the 28-volt essential DC bus through the APU CONT NORM circuit breaker on No. 1 power distribution panel.
What does the APU start module do?
Provides signal pressure for the APU motor pump.
What does the APU motor pump do?
Motor drives the APU during the start sequence.
Pump provides the pressure for the utility hydraulic system during ground operations.
What does the APU electronic sequencing unit do?
Monitors the APU during start and shut down.
What is the APU fault relay?
Closes the fuel solenoid valve during ESU shut down of the APU.
What does the APU fuel boost pump do?
Boost fuel pressure during APU start.
What does the APU fuel solenoid valve do?
Stops fuel flow to the APU.
What is the APU generator rated at?
20 KVA
What’s the main difference between the APU engine and the 47’s 714 engine?
The APU is not a free-air type turbine. The compressor rotor and power turbine rotor are directly mounted to a common shaft. This is different from the T55−GA−714 Engine where the compressor section and power turbine section are free to rotate independently of one another.
What does the manual depressurization valve do?
It is used to depressurize the APU start accumulator and the reservoir pressurization accumulator (URPA) to facilitate maintenance on the utility system. The valve is located on the bottom center of the apu start module.
