Service difficulty report · Magneto · Cessna 172S

Difficulty date
June 11, 2008
Submitted
July 10, 2008
Operation
General aviation
Aircraft
N712DS
Make and model
Cessna 172S
Aircraft serial
172S10711
Engine
Lyc IO360L2A
Part
Magneto
Part number
4371
Part serial
07110316LT
Condition
Out Of Position
Location
Powerplant
Part time
98 hours
Stage of operation
IN
How discovered
9
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

DURING THE AC FIRST PHASE 2 INSPECTION (100 HR) FOUND THAT BOTH MAGNETOS WERE OFF APPROXIMATELY 5 DEGREES. CURRENTLY SET 30 DEGREES BEFORE TOP DEAD CENTER PLUS (MFG SUM SAYS 25 DEGREES BTDC) THE AIRCRAFT MAGNETO TO ENGINE TIMING WAS CHECKED WHEN NEW, SHORTLY AFTER DELIVERY 4/25/2008, 4.3 HRS TIS. IT APPEARS THE MAGNETOS HAVE DRIFTED TO THE ADVANCED POSITION. ORANGE PUTTY ON THE MAGNETO HOLD-DOWN STUDS WAS NOTED. IT APPEARS THE MAGNETOS HAVE DRIFTED SIGNIFICANTLY TO THE ADVANCED POSITION IN 93 HOURS TIS. THE MAGNETOS DRIFTING TO THE ADVANCED POSITION TO THE ENGINE TIMING HAS BEEN AN ONGOING ISSUE WITH MFG OF ENGINE AND MFG OF MAGNETO SB2-08 DOES NOT ADDRESS AN ADVANCED CONDITION OF THE MAGNETOS AS IN THIS CASE. (K)

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