# SDR JYD2002F00001

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: December 6, 2001
- Submitted: February 11, 2002
- Operation: Air carrier
- Aircraft: [N157AC](https://openairdocs.org/aircraft/N157AC), registered now
- Make and model: Skrsky S64F
- Aircraft serial: 64065
- System (JASC): [6320 · Main Rotor Gearbox](https://openairdocs.org/jasc/6320)
- Part: Support
- Part number: 643520026012
- Part serial: 33
- Condition: Cracked
- Location: M/R Gearbox
- Part time: 1,296 hours
- Stage of operation: IN
- How discovered: V
- Nature of condition: O
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/JYD2002F00001

## Discrepancy

3 CRACKS WERE FOUND IN LWR SUPPT E MODEL MN GEARBOX WAS REMOVED FROM SERVICE FOR O/H IN1995.  IN DECEMBER OF 2001, SUPPT WAS MACHINED TO REMOVE CORROSION.  AFTER MACHINING, CRACK WAS VISUALLY DETECTED IN MOUNTING LUG HOLE NR 4 AS INSTALLED ON AC.  FLUORESCENT PENETRANT INSP VERIFIED THIS WHILE DETECTING 2 ADDITIONAL CRACKS IN MOUNTING LUG HOLE NR 1 AND NR 4, FOR A TOTAL OF 3 CRACKS.  LONGEST CRACK WAS .750 INCH STARTING FROM BOTTOM (MATING) SURFACE EXTENDING AT A 45 DEGREE ANGLE THROUGH 45 DEGREE CHAMFER AND UP INTO WALL OF.9730 DIA MOUNTING HOLE.  NOTE: 12 MOUNTING HOLES EXIST.  HOLES ARE FOR BOLTS WHICH ATTACH THE MN GEARBOX TO AIRFRAME.  NO PROBABLE CAUSE DETERMINED AT THIS TIME.

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