APU Flashcards
Where is the APU located?
Inboard of the right engine nacelle aft of the main transmission in the aft equipment bay under a Kevlar enclosure
What is the approximate fuel burn for the APU per hour?
175 lbs per hour
What three things does the APU enclosure provide for the APU?
- Confines the APU in the event of a fire for extinguishing purposes
- Inlet screen allows cool air to flow across the APU for cooling
- APU air inlet screen is used to allow ambient air to be used for combustion
Where does the APU receive its fuel in the AH-64E model aircraft?
AFT fuel cell (only)
What does the APU Electronic Control Unit (ECU) provide?
Operational sequencing control for automatic starting, PTO clutch operation, normal operation, and APU protection.
What does the PTO clutch provide?
Coupling and de-coupling between the APU and the main transmission accessory assembly via the number seven drive shaft
Where is the APU oil level sight gauge located?
Underneath the No. 2 engine nacelle panel RN5
When viewing the APU oil level, where should the oil level be in the sight gauge?
Ball bearing is in the center when the APU is properly serviced (1/2 full)
The APU is divided into two major sections. What are they?
Power Section
Accessory Section
The PTO clutch normally engages when the APU reaches what percent speed?
60% APU speed
During cold weather operation with the transmission oil temperature below 0 degree Fahrenheit, when will the PTO clutch engage?
95% APU speed
The load control valve will open at 95% APU speed and will remain open until what two actions occur?
APU is shutoff or if the APU FIRE/ READY switch is pressed
Where is the APU start push button located?
Pilots Power Lever Quadrant Control Panel
What are the minimum aircraft requirements that must be present prior to starting the APU?
(a) Battery or external power
(b) Minimum 2600 PSI
(c) Fuel in the AFT cell
(d) APU oil level in the sight glass half full
How do you start the APU?
- Master ignition switch is rotated to BATT or EXT PWR
- APU control Switch depressed