# SDR 98ZZZX3543

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: September 1, 1998
- Submitted: March 26, 2000
- Operation: General aviation
- Aircraft: [N100VB](https://openairdocs.org/aircraft/N100VB), registered now
- Make and model: Bell 47G-3B-1
- Registry model: [Bell 47G-3B-1](https://openairdocs.org/model/bell-47g-3b-1) (OpenAirDocs)
- Aircraft serial: 3552
- System (JASC): [6320 · Main Rotor Gearbox](https://openairdocs.org/jasc/6320)
- Part: Bearing
- Part number: 476206283
- Condition: Misinstalled
- Location: Transmission
- Component: 4762060027
- Stage of operation: IN
- Nature of condition: W
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/98ZZZX3543

## Discrepancy

BEARING FAILED AFTER INCORRECT INSTALL.  INSP OF WHAT APPEARED TO BE EXCESS BACKLASH ON THE 47-620-497-1 FAN DRIVE GEAR ASSY.  UPON REMOVAL OF FAN DRIVE QUILL ASSY, NOTED NEW GEAR PATTERN AFT AND HIGH RUNNING OFF HEEL OF 530 GEAR.  UPON REMOVAL OF CLUTCH, DETERMINED 47-620-628-3 DUPLEX BEARING SET FAILED DUE TO IMPROPER INSTALL WHEN NEW CLUTCH ASSY INSTALLED 56.7 HRS PRIOR.  PER BELL TECH BULLETIN NR 47-75-4, REV A, PAGE 4 OF 4, FIG 4, DUPLEX BEARING SET IS TO BE INSTALLED WITH THRUST SIDE OF EACH BEARING OTBD AS WRITTEN ON BEARING RACE.  HOWEVER, BEARING SET HAD BEEN INSTALLED IN A TANDUM CONFIG AND FAILED WITHIN 56.7 HOURS.  TRANS TSO:  165.1 HRS.  DUPLEX BEARING:  56.7 HRS SINCE INCORRECT ASSY AND INSTALL.

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