Service difficulty report · Magneto · Cessna 172S

Difficulty date
June 16, 2008
Submitted
July 10, 2008
Operation
General aviation
Aircraft
N987AP
Make and model
Cessna 172S
Aircraft serial
172S10710
Engine
Lyc IO360L2A
Part
Magneto
Part number
4371
Part serial
07112028
Condition
Out Of Position
Location
Engine
Stage of operation
IN
How discovered
C
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

CHECKED THE MAGNETO TIMING AND FOUND THAT BOTH MAGNETOS WERE OFF APPROX 5 DEGREES. CURRENTLY SET AT APPROX 30 DEGREES BEFORE TOP DEAD CENTER. MFG SPEC IS 25 DEGREES BTDC. THE AIRCRAFT ENGINE TO MAGNETO TIMING WAS CHECKED WHEN NEW, SHORTLY AFTER DELIVERY 4/14/2008- 3.5 HRS TIS AND FOUND OK. IT APPEARS THE MAGNETOS HAVE DRIFTED SIGNIFICALLY TO THE ADVANCED POSITION. ORANGE FACTORY PUTTY NOTED ON MAGNETO HOLDOWN NUTS. IT APPEARS THE MAGNETOS HAVE DRIFTED SIGNIFICALLY TO THE ADVANCED POSITION IN 80 HRS TIS. THE MAGNETOS DRIFTING TO THE ADVANCED POSITION TO THE ENGINE TIMING HAS BEEN AN ONGOING ISSUE WITH MFG. SB SB2-08 DOES NOT ADDRESS AN ADVANCED CONDITION OF THE MAGNETOS, AS IN THIS CASE.

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