Service difficulty report · Magneto · Cessna 172N

Difficulty date
October 1, 2018
Submitted
January 15, 2020
Operation
General aviation
Aircraft
N4844F
Make and model
Cessna 172N
Aircraft serial
17273088
Engine
Lyc O320H2AD
Part
Magneto
Part number
1068255514
Part serial
G04LA114R
Condition
Malfunctioned
Location
Engine
Stage of operation
NR
How discovered
9
Nature of condition
O
Precautionary procedure
O

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

What was found

RIGHT SIDE OF MAG FAILED CHECK. UPON INSPECTION IT WAS FOUND THAT THE LEFT SIDE WAS TIMED TO 22 AND THE RIGHT SIDE WAS TIMED TO 10 BTDC, ALSO THE RIGHT POINTS WERE ONLY OPENING EVERY OTHER CYLINDER CAUSING IT TO ONLY FIRE 2 OF THE 4 CYLINDERS. WHEN I OPENED THE MAG FOR AN INTERNAL INSPECTION I FOUND THAT THE POINTS WERE NOT TORQUED AND HAD MOVED TO THE POINT THAT THEY WERE NOT OPENING AT THE PROPER E-GAP. RESETTING THE INTERNAL TIMING AND RE-TIMING THE MAG TO THE ENGINE SOLVED THE MAG ISSUE. MY CONCLUSION IS THAT WHEN QUALITY AIRCRAFT ACCESSORIES OVERHAULED THE MAG THEY DID NOT PROPERLY TORQUE THE POINTS CAUSING THEM TO SHIFT UNDER USE.

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