# SDR 95ZZZX4496

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: August 15, 1995
- Submitted: March 26, 2000
- Operation: General aviation
- Aircraft: [N8450E](https://openairdocs.org/aircraft/N8450E), registered now
- Make and model: Cessna 172
- Registry model: [Cessna 172](https://openairdocs.org/model/cessna-172) (OpenAirDocs)
- Aircraft serial: 17272205
- Engine: Lyc O320D2J
- System (JASC): [8540 · Reciprocating Engine Rear Section](https://openairdocs.org/jasc/8540)
- Part: Idler Gear
- Part number: 74996
- Condition: Teeth Missing
- Location: Lt Magneto
- Stage of operation: NR
- Nature of condition: R
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/95ZZZX4496

## Discrepancy

PILOT REPORTED BAD LT MAG DROP.  LT MAG REMOVED AND VISUAL INSPECTION REVEALED MISSING TOOTH ON IDLER GEAR.  ALL REMAINING TEETH FOUND TO BE DISTORTED.  IDLER GEAR BOSS ON CRANKCASE FOUND LOOSE.  LT BOLT SAFETY BROKEN.  RT HAD STUD WITH COTTER PIN THROUGH NUT, HOWEVER, SHOULD HAVE BEEN BOLT WITH SAFETY WIRE.  THE STUD APPEARS TO HAVE BACKED OUT NUT, COTTER PIN AND ALL.  PILOT OF A/C WENT TO OFF ON MAG SWITCH AND BACK ON AND NOTICED BACKFIRE.  THIS AND IMPROPER INSTALLATION OF GEAR ARE SUSPECT TO THE FAILURE.

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