# SDR 99ZZZX4578

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: September 8, 1999
- Submitted: March 26, 2000
- Operation: General aviation
- Aircraft: [N407AL](https://openairdocs.org/aircraft/N407AL), registered now
- Make and model: Bell 407
- Registry model: [Bell 407](https://openairdocs.org/model/bell-helicopter-textron-canada-407) (OpenAirDocs)
- Aircraft serial: 53044
- System (JASC): [6520 · Tail Rotor Gearbox](https://openairdocs.org/jasc/6520)
- Part: Case
- Part number: 406040406101
- Condition: Worn
- Location: T/R Gearbox
- Part time: 3,616 hours
- Component: 407040400115
- Stage of operation: IN
- Nature of condition: O
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/99ZZZX4578

## Discrepancy

PRE-FLIGHT INSPECTION FOUND MOUNTING PADS WORN BEYOND LIMITS IN BHT 407 CR&O MANUAL.  ONE EACH DOW ALIGNMENT PIN BROKEN.  FURTHER TEAR-DOWN REVEALED HIGH GEAR BACKLASH AND SCARING OF THE GEAR TEETH.  POSSIBLY DUE TO  LOW OR ABSENCE OF OIL AT THE SAME TIME.  HIGH VIBRATION CAUSED GEARBOX TO LOOSEN UP.

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