Service difficulty report · Bolt · Cessna 172RG

Difficulty date
November 13, 2016
Submitted
December 5, 2016
Operation
General aviation
Aircraft
N751DW
Make and model
Cessna 172RG
Aircraft serial
172RG1002
Engine
Lyc O360F1A6
Engine time
7,217 hours
Part
Bolt
Part number
SL75061
Condition
Broken
Location
Connecting Rod
Stage of operation
NR
How discovered
9
Nature of condition
O
Precautionary procedure
O

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

BOLTS USED FOR THE NUMBER TWO CONNECTING ROD AND END CAP. ONE OF THE BOLTS SHOWED SIGNS OF A 45 DEGREE FRACTURE AND SIGNS OF BEING STRETCHED AND BENDING CAUSING THE BOLT TO BREAK. THE END CAP ALSO SHOWED SIGNS OF BEING DEFORMED FROM ONE OF THE TWO BOLTS FAILING CAUSING THE REMAINING BOLT TO CARRY THE LOAD OF TWO. THE OTHER BOLT HAD FRACTURED AT THE LOWER THREADED AREA WITH SIGNS OF STRESS FATIGUE AND IS BELIEVED TO BE THE FIRST BOLT TO FAIL. THIS APPEARS TO BE THE REASON FOR THE NUMBER TWO CONNECTING ROD FAILURE.

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