# SDR 97UAL900203

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: March 12, 1997
- Submitted: March 26, 2000
- Operation: Air carrier
- Aircraft: [N780UA](https://openairdocs.org/aircraft/N780UA), registered now
- Make and model: Boeing 777222
- Aircraft serial: 26944
- Engine: Pwa PW4077
- System (JASC): [4940 · APU Start/Ignition System](https://openairdocs.org/jasc/4940)
- Part: Gear
- Part number: 38608231
- Condition: Failed
- Location: Apu Starter
- Part time: 1,518 hours
- Stage of operation: NR
- Nature of condition: O
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/97UAL900203

## Discrepancy

APU WILL NOT START.  BATTERY REPLACED FOR LOW VOLTAGE AND STARTER REPLACED.  STILL NO START.  FOUND STARTER GEAR (P/N 3860823-1) WORN AND ELECTRIC CLUTCH PACK DAMAGED.  ADDITIONAL, DAMAGE FOUND IN AREA OF CLUTCH HOUSING DURING CLUTCH REMOVAL RESULTED IN APU REPLACEMENT.  *S/D*  PREVIOUS OCCURANCES TRACED TO STARTER ENGAGEMENT DURING APU OPERATION AS A RESULT OF OPENING CERTAIN CIRCUIT BREAKERS WHILE PERFORMING OTHER MAINTENANCE.  BOEING IS PLANNING ON RELEASING A SERVICE BULLETIN TO PREVENT STARTER ENGAGEMENT WHEN AFFECTED CIRCUIT BREAKERS ARE OPEN.

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