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Date:  4-19-2022
Number of Hours:  3.00
Manual Reference:  23-?
Brief Description:  Engine forward seal retainer

Latest COBA mag speaks of the requirement for engine crankshaft seal retainers, a concept I was familiar with and had intended to do. Why not now! Details in the JAN22 issue #145 page 14.

Do a bit of research and in incomplete and confusing picture emerges of multiple ways of going about it. CSA #64 JAN01 page 25 and CSA#30 APR93 page 18 gave more information, but not templates, or agreement on materials or what it should look like or how to mount it. I find the genuine Lycoming part #74113 which looks way skimpier than any examples of installed versions I can find. An incredibly annoying video from a RV builder shows the cased drilled and tapped for the retainers, without mentioning ANYTHING about them...

Decide on 0.063" 2024, as this is reference on one site that sells the genuine Lycoming part. Made a paper template, and confirm that one side is the mirror of the other (vertically). The aim was for the attach points to have a reasonable edge radius from the holes, (unlike the Lycoming part), but be about the same clearance from the crankshaft. Use the paper to make two retainer plates and drill 1/8" pilot holes. I prop the plates in position with sticks and magnets and chewing gum and mark the crankcase and drill matching 1/8" holes 1/2" deep, securing each hole with a 1/8" rivet, as cleco won't fit behind the flange. There are no explosions or fountains of oil so I am much encouraged.

The COBA article indicates you need to remove one of the bosses from the prop flange to do this job, but I could access all the holes either through the centre of the boss or through the lightening holes betwixt, so I didn't. I didn't understand the instructions anyhow...

Now waiting for a 1/4" UNF bottom tap from Ebay Aerospace.
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Drilly, drilly.

Drilly, drilly.

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Um. Looks OK to me!

Um. Looks OK to me!

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