Service difficulty report · Coil · Cessna 172M

Difficulty date
July 2, 2008
Submitted
November 3, 2008
Operation
General aviation
Make and model
Cessna 172M
Aircraft time
12,513 hours
Engine
Lyc O320E2D
Propeller
Mcauly 1C160DTM
Part
Coil
Part number
M3975
Condition
Worn
Location
Magneto
Part time
1,286 hours
Component
Magneto · Slick · 4370
Stage of operation
IN
How discovered
V
Nature of condition
W
Precautionary procedure
O

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

What was found

(CAN) SB 3-08 DEALS WITH THE PROBLEM OF COIL HIGH-VOLTAGE OUTPUT TABS BEING BENT SLIGHTLY DURING MAGNETO MFG. THE DISTRIBUTOR ROTOR HAS A SPRING-LOADED CARBON BRUSH THAT RIDES ON THIS TAB, AND IF THE TAB IS NOT PERPENDICULAR TO THE ROTOR SHAFT, L THE BRUSH IS THRUST SIDEWAYS IN THE ROTOR SHAFT BORE, WEARING THE SIDES OF THE BRUSH AND CUTTING A HALF-MOON DEPRESSION IN THE COIL TAB. THIS TAB WAS SLIGHTLY OFF-LEVEL AND WAS WORN AS DESCRIBED. THE BRUSH WAS ALSO SOMEWHAT WORN ON ITS SIDES.

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