Service difficulty report · Brushes · Cessna 172M

Difficulty date
January 21, 2009
Submitted
March 5, 2009
Operation
General aviation
Make and model
Cessna 172M
Aircraft time
20,960 hours
Engine
Lyc O360A4M
Part
Brushes
Part number
K3215
Condition
Damaged
Location
Magneto
Component
Magneto · Slick
Component part number
43704371
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

WHILE PERFORMING SB3-08 ON BOTH LEFT AND RIGHT MAGNETOS LT P/N 4370 LT S/N 08010485 LT TSN 64.7 AND RT P/N 4371 RT S/N 07111952 RT TSO 400.6 THERE WAS EVIDENCE OF IMPROPER WEAR OF THE CARBON BRUSH. THE COIL TAB HAD RESIDUE COATING AND UNACCEPTABLE WEAR MARKS. UNDERCUTTING WAS ALSO NOTED ON THE CARBON BRUSH. IT WAS LATER LEARNED THAT BOTH MAGNETOS HAD THE NEW BRUSH REPLACEMENT AND TERMINATING ACTION IMPLEMENTED. THE AFFECTED MAGNETOS WERE SUBSEQUENTLY REPLACED WITH OTHERS AND WERE SENT OUT FOR REPAIR.

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