Service difficulty report · Control Cable · Cessna 172

Difficulty date
December 10, 2020
Submitted
December 10, 2020
Operation
General aviation
Aircraft
N5907E
Make and model
Cessna 172
Aircraft serial
17271957
Aircraft time
4,265 hours
Engine
Lyc O360A4M
Engine time
553 hours
Part
Control Cable
Part number
98620105
Condition
Binding
Location
Mixture
Part time
4,265 hours
Stage of operation
NR
How discovered
O
Nature of condition
R
Precautionary procedure
O

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

What was found

APPROXIMATELY 20 HOURS AFTER ANNUAL, THE VERNIER MIXTURE CONTROL BECAME VERY STIFF. THERE WERE NO KNOWN ANOMALIES OR WEAR NOTED AT THE ANNUAL. DUE TO THE AGE OF THE PART, IT WAS REPLACED. UPON, DISASSEMBLY THE VERNIER PART OF THE CONTROL APPEARED TO STILL WORK APPROPRIATELY, BUT THERE APPEARED TO BE A LARGE AMOUNT OF BLACK MATERIAL THAT HAD BUILT UP ON THE LENGTH OF THE CABLE (ESPECIALLY NEAR THE TOP OF THE CABLE ASSEMBLE, NEAR THE TOP OF THE VERNIER CONTROL). THE CABLE APPEARED TO BE GUMMY IN NATURE. UPON POLLING OWNERS, SOME OWNERS MAY HAVE USED SANITIZER THAT INCLUDED PHENOLS AND/OR METHANOL THAT MAY HAVE BROKEN DOWN THE BLACK PHENOLIC HOUSING OF THE VERNIER MIXTURE. A LIGHT LOCALIZED CLEANING REMOVED THE RESIDUE AND APPEARED TO BE INCONSISTENT WITH DIRT.

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