# SDR 2008UALA01004

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: February 24, 2008
- Submitted: February 26, 2008
- Operation: Air carrier
- Aircraft: [N228UA](https://openairdocs.org/aircraft/N228UA), registered now
- Make and model: Boeing 777222
- Aircraft serial: 30556
- Aircraft time: 24,583 hours, 3,168 cycles
- Engine: Pwa PW4090
- Engine time: 25,331 hours, 3,631 cycles
- System (JASC): [7260 · Turbine Engine Accessory Drive](https://openairdocs.org/jasc/7260)
- Part: Bearing
- Condition: Failed
- Location: Main Gearbox
- Stage of operation: IN
- How discovered: O
- Nature of condition: W
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/2008UALA01004

## Discrepancy

FOUND EXCESSIVE BLACK METAL COVERING CHIP DETECTOR HEAD, AT NR 2 ENG MAIN OIL TANK (MCD).  FOUND GEARBOX (MCD) FULL OF METAL CONTAMINATION.  ENGINE REPLACED AT ORD. THE MB-7 AND MB-8 BEARINGS IN THE MAIN GEARBOX WERE FOUND TO HAVE FAILED. PRATT & WHITNEY HAS RECEIVED THIS HARDWARE, AND ARE INVESTIGATING FURTHER. THEIR HYPOTHESIS IS THAT THE MB-8 BEARING IS BACKING OFF THE DRIVESHAFT SHOULDER.  THIS CAUSES CROSS LOADING ON THE MB-7 BEARING, WHICH SUBSEQUENTLY FAILS.



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