Service difficulty report · Ignition Switch · Cessna 172S

Difficulty date
January 6, 2011
Submitted
January 6, 2011
Operation
General aviation
Aircraft
N348ME
Make and model
Cessna 172S
Aircraft serial
172S8582
Aircraft time
3,471 hours, 3,471 cycles
Engine
Lyc IO360LYC*
Part
Ignition Switch
Part number
A5109C292501107
Part serial
JUL072000
Condition
Failed
Part time
3,471 hours, 3,471 cycles
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

THE IGNITION SWITCH HAS NEVER BEEN INSPECTED IAW SEB91-5R1 TO COMPLY WITH AD 93-05-06. UPON DISASSEMBLY OF THE SWITCH, THE CIRCUIT BOARD PLATE WAS FOUND TO BE SEVERLY WORN AND 1 CONTACT POINT WAS BURNED. 1 CONTACT CUP WAS BURNED COMPLETELY THROUGH CREATING A HOLE IN THE CONTACT POINT. THE SCREW HEADS HOLDING THE BODY OF THE SWITCH TO THE TERMINAL BOARD ASSY WERE PAINTED RED AS REQUIRED BY SEB91-5R1 AND AS DESCRIBED BY IDENTIFICATION OF A FACTORY NEW SWITCH; HOWEVER THERE WAS NO VISIBLE GREASE ON THE CUPS OR CIRCUIT BOARD. DISCUSSIONS WITH OTHER MECHANICS AND INSPECTORS LEADS ME TO BELIEVE THAT THIS AD IS OVERLOOKED DUE IN PART TO MECHANICS ASSUMING THAT NO AD EXISTS FOR SWITCHES MFG AFTER 1993. THE TEXT OF THE AD AS WELL AS THE TEXT IN SEB91-5R1 AND ACS SB92-01 DO NOT SUPPORT THIS ASSUMPTION.

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