20 November 2017

Maintenance: Propeller governor leak

My prop governor was leaking a tiny drip of oil every few days.  This was prior to my running the engine.  I have Hartzell's S-1-79 governor.  I removed the governor head (model 102889 Rev. 6) and found the below.  You can see that the o-ring apparently was pinched when installed.  I spoke to a Hartzell A&P and he thought it happened during assembly at the plant and was the first time he'd seen this.


The o-ring part number is  C-3317-035 with a 2016 list price of $2.70.  The replacement part was covered under warranty.


The damaged ring on the left and the new ring on the right.


When replacing the ring, I learned that it's important to lubricate it with oil and to stretch it in place not roll it.  It's trivial to reinstall.  The 9/32" hex cap head screws must be torqued to 21-25 in-lbs per the manual (HC-SL-61-277 Rev. 3 D(1)(b)g).

Then I needed to be sure the speeder compress spring sits properly when reassembling.  Left image is of course incorrect, whilst the right is correct.


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