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Lycoming Fixed Pitch

Mel

Legacy Member
Mentor
Lycoming Shipping for Fixed Pitch

When I built my RV-6, eons ago, Lycoming shipped new engines with both front crankshaft plugs in place. To use a fixed pitch prop, one must remove the front plug, remove or puncture the rear plug, and install a new front plug.

I inspected an airplane yesterday and the builder is under the impression that Lycoming now ships new engines without the rear plug if you specify fixed pitch operation. I've not heard of this and suggested that he remove the front plug to verify. Anyone know if this is true?
 
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I inspected an airplane yesterday and the builder is under the impression that Lycoming now ships new engines without the rear plug if you specify fixed pitch operation. I've not heard of this and suggested that he remove the front plug to verify. Anyone know if this is true?

It is my understanding that on a new engine purchased from Van's, the engine is shipped as a constant speed configured engine with a plug installed in the front, for storage and shipping purposes, and if it is to be used with a fixed pitch prop it needs to be modified (and I think it comes with a document in the box indicating that, and how to modify it if needed).
 
Yep.....

It is my understanding that on a new engine purchased from Van's, the engine is shipped as a constant speed configured engine with a plug installed in the front, for storage and shipping purposes, and if it is to be used with a fixed pitch prop it needs to be modified (and I think it comes with a document in the box indicating that, and how to modify it if needed).

That is my understanding also, and I just talked with Lycoming and they confirmed same.
The interesting thing is that documentation that came with the engine states that it was shipped set up for fixed pitch. The engine is a AEIO-320-EXP. I'm recommending that he remove the front plug and verify.
 
Crank plugs

Mel,

Certain engines were shipped with BOTH plugs in the crankshaft, with the oil return line to the governor pad. BUT, the governor pad cover was MODIFIED to allow the oil to return to the sump. My engine came this way from Mattituck when they were out on Long Island..... It's still setup this way after 1672 Hrs...
 
IO360M1B

The documentation that came with my Vans supplied Lycoming IO360M1B says,

Crankshaft expansion plug,

If the engine installation requires a variable pitch propeller, you must remove the expansion plug from the front of the crankshaft prior to installing the propeller.

If the installation requires a fixed pitch propeller, the plug should remain in place.


The above is verbatim from the installation documents supplied, I have a fixed pitch Catto and left the plug in and the oil pressure etc performs as advertised.
 
Mel,

Certain engines were shipped with BOTH plugs in the crankshaft, with the oil return line to the governor pad. BUT, the governor pad cover was MODIFIED to allow the oil to return to the sump. My engine came this way from Mattituck when they were out on Long Island..... It's still setup this way after 1672 Hrs...

…..my YO360-A1A bought from Van's around 15 or so years ago has the modified governor pad cover and after discussing with tech support at Lycoming I didn't remove either of the crank plugs for my FP prop installation. I guess a potential problem over time is that the governor pipe might accumulate crud, become blocked and allow pressure to build up on the crank nose plug. I'll see if I can find a picture of the pad cover with the return drain groove. The square boss on the bottom left allows for a groove in the cover that lets oil drain from the crank nose bearing through the governor oil tube and back into sump.

Jim Sharkey
RV6 - flying since 2009
 
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