APU Flashcards
What is the name of the APU?
Honeywell GTCP36-150
How does the APU protect itself from faults that would cause automatic shutdown?
It has a fully automatic start system and is self monitoring
What type of power does the APU require for starting, fuel supply, and control input signals for operation?
DC power
What bottle supplies fire extinguishing to the APU compartment?
2 Fire Bottle
What are the major sections and subsystems of the APU?
Power section
Electronic Control Unit
Air inlet system
Exhaust system
Accessory gearbox
Fuel supply
Oil and lubrication
Bleed air system
Electrical system
What does the electronic control unit do for the APU?
Monitors selected APU parameters for operational limits, and if exceeded, will automatically shut down the APU or prevent starts depending on the mode of operation
What controls the air inlet door on the APU?
The APU MASTER switch - when turned on or off
What is the power section of the APU comprised of?
Single stage centrifugal compressor, a reverse flow annular combustor, and a single stage radial inflow turbine
What does the accessory gearbox do for the APU?
Converts high turbine speeds to values required to drive the APU & accessories which are:
Starter-generator
Oil pump
Fuel control unit
How many fuel nozzles are in the combustion chamber? How many igniters?
Six, one igniter
When is the APU fuel shutoff valve opened?
During the start cycle when turbine speed reaches 7-10%
How many quarts of oil are in the APU?
2 quarts
What is the purpose of the monopole pickup transducer?
Provides input to the ECU after APU has started. Includes:
Initiation of fuel flow and ignition at 7 to 10%
Starter drop out at 50%
Acceleration fuel scheduling
Ignition drop out at 95%
Generator arming at 95% +4 seconds
What control valve arming at 95% +90 seconds
On-speed fuel governing at 100%
What does BITE mean in regards to the ECU performing a “BITE” check?
Built in test equipment
When is the APU in Essential mode?
When APU is operated weight off wheels and for 15 minutes after transition to weight on wheels
