APU Flashcards
Actions and Limits: “LOW OIL LEVEL” ECAM
If ECAM displayed on the APU SD page prior to start: Advise Maintenence. Limited to 15 hrs use after message is displayed
Starter Limits
3 starts, 60 min cooldown
Start limit (normal aircraft supply vs. APU battery only) altitudes
Normal: 41450 ft
APU BAT: 25000 ft
Operating Envelope Altitude Limit: APU Electrical Use
41450 ft
Operating Envelope Altitude Limit: APU Electrical Use + APU bleed for 1 pack
22500 ft
Operating Envelope Altitude Limit: Engine Start using APU bleed
20000 ft
Operating Envelope Altitude Limit: APU Electrical Use + APU bleed for 2 packs
17500 ft
Exterior Locations to shutdown APU
- Refueling Panel
- External Power Panel
APU Bleed valves automatically close climbing through ____ and reopen passing _____
ECB (Electronic Control Box) closes APU Bleed Valves climbing thru FL250 and reopen descending thru FL230
What happens in case of APU Fire on ground
- APU FIRE Warnings in Cockpit
- Horn in nose gear bay sounds
- APU “AVAIL” light extinguishes
- “FAULT” light in Master sw illuminates
- APU Shutsdown
- APU Fire extinguisher discharges
APU Master sw FAULT means?
Automatic shutdown of APU has occurred.
On ground: overspeed, ECB (Electric Control Box) critical failure, underspeed, start abort, low oil pressure, high oil temp, load compressor overtemp, generator high oil temp, DC power interruption (disconnect when aircraft on BAT only), overtemp
In Flight: Overspeed, certain critical ECB internal Failures
APU Master sw FAULT means?
An automatic shutdown of APU has occurred.
On ground: Overspeed, ECB (Electric Control Box) critical failure, under speed, start abort, low oil pressure, high oil temp, load compressor overtemp, generator high oil temp, DC power interruption (disconnect when aircraft on BAT only), overtemp
In Flight: Overspeed, certain critical ECB internal Failures
APU MASTER SW pb
Controls the electric supply for APU operation, its protective features, and start/shutdown sequences
FAULT: Automatic shutdown occurred
ON/R: Electric power to APU system, ECB power up test, APU air intake flap opens, APU fuel isolation valve and APU LP valve open, fuel made available
OFF: Manual Shutdown sequence; APU first runs for 15 s (no break in power transfer), if APU BLEED selected, APU performs cooling period for 85 sec at 82% N, at N 7% air inlet closes.
APU START pb
ON: blue light, when flap is completely open APU is energized, when N = 7% ignition on, N = 50% starter de-energized/ignition off, N = 95% “ON” light extinguishes.
AVAIL: green light, when N reached 95%, bleed air and electrical power available.
note: “AVAIL” remains on during, cooldown can take up to 2 min
APU Fuel Supply
- Engine 1 Collector Cells: on ground after 2 minutes (except during trim tank refueling), or inflight below FL255, or above FL255 when trim tank empty.
- Trim Pipe: first 2 min on ground, or during trim tank refueling, or during aft transfer
- Trim Tank: Above FL255, or during forward transfer
Fuel must be maintained in trim tank transfer line (trim pipe) for APU to function.
