200 auxiliary power unit Flashcards
What is the primary and secondary function of the APU?
The primary is electrical the secondary is pneumatic.
The primary function of the APU is to operate the assessory gearbox Mounted 30 kVA generator. BAP use a secondary function is to supply bleed air for air conditioning and engine starting
What is the maximum operating altitude of the APU?
36,000 feet PSA
Does the APU vary it’s RPM
The APU is required to run at a constant 12,000 RPM to maintain a frequency of 400 Hz
What controls and monitors all APU operations?
An automatic electronic control unit (ECU) Controls all of the APU operations.
Is the APU ECU DC or AC powered?
The ECU is DC powered
What is the maximum altitude to start the APU?
30,000 feet
What is the maximum altitude to use APU bleed air?
15,000 feet
What is the maximum altitude to start an engine with the APU?
13,000 feet
Where is the APU air intake located?
The intake is located on the upper left rear side of the fuselage.
How many positions does the APU intake door have?
It has three positions, open, mid, or closed.
What factors determine the position of the APU intake door?
The position is determined by the ECU and is based on aircraft altitude and true airspeed.
What is a limitation if the APU intake door is failed open or if the door position is unknown?
The airspeed is restricted to 300 knots or the APU must remain running then there will not be a restriction.
How many feet is the APU exhaust danger area?
15 feet
How was the APU lubricated?
The APU has a self-contained lubrication system. There is a gearbox mounted oil pump, oil cooler assembly, and an integral oil tank.
Where does the APU normally receive fuel?
The APU receives fuel from both wing tanks.
How is the APU shut down normally?
By pressing the APU START/STOP switch light there is a simulated overspeed signal generated to close the fuel solenoid SOV. This will stop the flow of fuel and the APU will shutdown.
How many pounds per hour does the APU burn?
Approximately 120 pounds
With electrical and bleed air loading
What does the green AVAIL in the APU START/STOP switch light indicate?
The light means that the APU is ready to accept bleed air loading. The slight will come on for seconds after the RPM is at 99% or more.
Which battery is used for starting the APU?
Both the main and APU batteries are required to start and operate the APU. The APU battery is used to turn on the APU starter and the main battery is used to operate the APU ECU.
What is the minimum battery voltage to start the APU?
22 V on both the main and APU battery.
Can the APU be shutdown from outside the aircraft?
There is a remote cut off switch located at the external services panel in the aft equipment bay on the APU.
