Service difficulty report · Tappet · Cessna 172M

Difficulty date
September 10, 2012
Submitted
September 14, 2015
Operation
General aviation
Make and model
Cessna 172M
Aircraft time
4,874 hours
Engine
Lyc O320E2D
Part
Tappet
Condition
Failed
Location
Engine
Stage of operation
NR
How discovered
O
Nature of condition
B
Precautionary procedure
O

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

What was found

(CAN) O/H ON O-320-E2D WITH NEW CAM AND TAPPET BODIES. SMOKE IN EXHAUST AT TAXI WHEN ENGINE WARM. OIL IN INDUCTION. CYLINDERS HONED AND CROSS HATCHED, ASSUMED TO BE THE PROBLEM) SMOKE AND OIL PROBLEM. NEW CYLINDERS INSTALLED. SMOKE AND OIL PERSISTS. ENGINE REBUILT. SMOKE AND OIL PERSISTS. ENGINE DISASSEMBLED AND FOUND THAT NEW TAPPET BODIES HAD A CLEARANCE WITHIN THE CRANKCASE OF .009-, .010 AND SERVICE LIMITS IAW O/H MANUAL 60294-7 ARE MAXIMUM .004. IT IS OF OUR OPINION THAT THIS ENABLED EXCESS OIL TO BE PUSHED DOWN THE PUSH ROD TUBE WHERE IT COLLECTED AND COULD NOT BE MOVED OUT OF THE VALVE TRAIN AREA UNDER THE ROCKER HAT FAST ENOUGH, AND CAUSED EXCESS OILING IN THE COMBUSTION CHAMBER AND INDUCTION SYS BECAUSE THE VACUUM AT IDLE IS HIGHER. INSTALLED O/H SET OF TAPPET BODIES FROM ACFT SPECIALTIES WHICH WERE WITHIN SERVICE LIMITS IAW O/H MANUAL AND THE PROBLEM WAS FIXED.

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