ELEC GEN OFF APU
π Sources: QRH 6.4 (R53), FCOM 6.30.1
1. QRH Reference & Condition
- QRH Section: 6.4
- EICAS Level: Advisory
- Condition: The generator control breaker is open.
2. Non-Normal Checklist
CAUTION
Attempt only one reset per flight.
| Step | Action |
|---|---|
| 1 | APU GEN switch β¦ β¦ Off, then ON |
- If message blanks: β β β β
- If message stays: APU generator remains failed
3. System Explanation
The APU generator OFF light illuminates when the APU is operating and the APU generator breaker is open due to: (FCOM 6.20.2)
- A fault detected with APU GEN switch ON β generator cannot connect to busses
- APU GEN switch manually selected OFF
The APU generator is electrically identical to the IDG generators (120 kVA). Loss of APU generator means:
- No backup AC source for main bus transfer
- Reduced redundancy on ground (if IDGs not available)
- In flight: IDGs remain primary, impact is reduced redundancy
4. Cross-References
- Electrical System β APU generator description
- APU System β APU operations
- ELEC GEN OFF L, R β Engine generator off