Service difficulty report · Pawl · Cessna 172N

Difficulty date
February 28, 2012
Submitted
April 19, 2012
Operation
General aviation
Aircraft
N739QL
Make and model
Cessna 172N
Aircraft serial
17270720
Engine
Lyc O320D2G
Part
Pawl
Condition
Loose
Location
Magneto
Part time
633 hours
Component
Magneto
Component part number
4371
Stage of operation
IN
How discovered
V
Nature of condition
O
Precautionary procedure
K

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

What was found

TRIED TO START ACFT, PROP WOULD TURN BUT IMPULSE COUPLING COULD NOT BE HEARD SNAPPING. REMOVED LEFT MAGNETO AND FOUND THAT THE RIVET HOLDING ONE OF THE PAWLS HAD BROKEN OFF AND THE PAWL WAS BEATING THE EDGE OF THE MAGNETO, DESTROYING THE LIP. THERE WAS ALOT OF AN OIL METAL PASTE ON ENGINE TO MAG SPACER AND WASHER THAT IS BETWEEN THE PAWL AND IMPULSE COUPLING WAS ON THE SPACER BUT THAT THE SPRING WAS MISSING. REMOVED FILTER AND FOUND THAT THERE WAS METAL IN THE FILTER. CAUSE OF THIS WAS THE RIVET THAT HOLDS THE PAWLS.

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