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Lycoming AD 1198-02-08 Crankshaft Bore

edclee

Well Known Member
Patron
If one has put 8.5:1 compression cylinders on a Lycoming 0-320-E2-A does this AD apply? As I read the AD, it applies to engines with hollow cranks of 160 hp if O-320 and all O-360 engines. Has anyone here had issues with this. My engine logs have never mentioned this AD but recently has had cylinder assemblies changed to 8.5:1. The E2-A is a 150 hp engine from a Cherokee 140.

How big a deal is it to remove the "freeze plug" from the snout of the crank and inspect for the possible corrosion pitting?
Ed
 
Crank bore corrosion

AD or not this is a area that should be inspected on some interval. Not all but many engines build up oil sludge in this area which contains combustion byproducts. Sometimes this gunk will cause rust in the crank bore. I have found rust and pitting in several cranks so cleaning out the sludge periodically might save you from buying a replacement crank $$$. The freeze plug is easy to remove and reinstall. I like the slide hammer method these days. On my planes I have a look every 5 years or more often if convenient. If you have the prop off for any reason you over 1/2 way there so consider it then. Good time to change the alternator belt too.

Don Broussard
RV9 Rebuild in Progress
57 Pacer
 
Like Don said...do it.

I had the same question of applicably about a year ago. I reality it doesn't matter unless you find pitting out of limits...then there's debate on legality. As far as the EAA is concerned AD's aren't applicable, but if your engine is ever removed and sold to be placed on a certified aircraft again, then there is conformity that needs to happen. Of course, the fact you have 8.5:1 on an -e2a make it experimental anyways.

It's a very easy inspection and the new freeze plug is cheap. You can also check your alternator belt at the same time and replace it since you have the prop off
 
If one has put 8.5:1 compression cylinders on a Lycoming 0-320-E2-A does this AD apply? As I read the AD, it applies to engines with hollow cranks of 160 hp if O-320 and all O-360 engines. Has anyone here had issues with this. My engine logs have never mentioned this AD but recently has had cylinder assemblies changed to 8.5:1. The E2-A is a 150 hp engine from a Cherokee 140.

How big a deal is it to remove the "freeze plug" from the snout of the crank and inspect for the possible corrosion pitting?
Ed
As was said you don't strictly have to comply with an AD in an experimental but.... why not. Next annual (err condition inspection) do this inspection. My RV4 I built and sold had an O320 and constant speed prop. The CS prop cranks tends not to have issues as oil is always flowing in that hollow crank shaft area near the flange. Never the less I looked when prop was off....

This AD decades old (1998) references a Lyc Textron Lycoming Mandatory Service Bulletin (MSB) No. 505A, dated October 18, 1994.
https://www.lycoming.com/sites/default/files/Inspection of Crankshaft ID for Corrosion.pdf

https://rgl.faa.gov/Regulatory_and_...E7B86DE103CB30E78625684D006644B5?OpenDocument

Hollow cavity for CS prop on a fixed pitch prop planes are prone to collect moisture on the ID of the crankshaft.... this causes corrosion pitting and eventual a fatigue crack. Out of the tens of thousands of engines over many decades there has been 10 failures at the time of the AD.

Big deal to remove freeze plug and replace it with a new one? No.
https://youtu.be/rHhj7myY1s8

You will clean the ID of crank and look for pits. If no corrosion good to go (until next engine OH or 5 years). However if you find PITS you should do a dye pen or florescent penetrant inspection. The SB says if corrosion found repeat inspection every 100 hours until crank is replaced. For dye pen inspection get someone who knows what they are doing and has the kit/tools to do the inspection. In the unlikely event you have pitting and a crack, after many flight hours it could lead to separation of the crank flange and your prop....
 
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Did it!

Big deal to remove freeze plug and replace it with a new one? No.
https://youtu.be/rHhj7myY1s8


Decided it is best to do it. I bought two new plugs from Aircraft Spruce, then drilled a hole in the middle of the plug and pried it out. You would not believe the dry oil crud in that hollow crank end! It took a while to get it all out and then clean it up so I could inspect it, but I found a perfect surface with no corrosion evidence at all. :D

Putting the new plug in, it fits nice and close. Make sure the sealing surface is clean, then take a large, say 1/2' drive extension that has a rounded end (the end that goes in a socket) and hit the extension with a hammer in the center of the plug. This expands it into the crankshaft. Works a charm.

Anyone having an engine needing this inspection should do it, not big deal and you can sleep better at night...either way it turns out. Thanks very much for the comments and the video reference.
Ed
 
Bad Advice.......

Big deal to remove freeze plug and replace it with a new one? No.
https://youtu.be/rHhj7myY1s8
Decided it is best to do it. I bought two new plugs from Aircraft Spruce, then drilled a hole in the middle of the plug and pried it out. You would not believe the dry oil crud in that hollow crank end! It took a while to get it all out and then clean it up so I could inspect it, but I found a perfect surface with no corrosion evidence at all. :D
Ed

PLEASE DO NOT DRILL the old plug out! Use a large punch instead. With drilling, there's always a chance that you won't get ALL the chips out.
 
Drilling

PLEASE DO NOT DRILL the old plug out! Use a large punch instead. With drilling, there's always a chance that you won't get ALL the chips out.

I used a high suction shop vacuum with a small extension tip held right at the drill hole to suck the chips out as I drilled. It seemed to work since I found no chips inside. In my case, the bore had a hard caked layer all around about 1/4" thick and chips would not have been an issue anyway. It took an hour to get all that out and get down to the metal. Any chips would certainly have been removed. YMMV.
Ed
 
Freeze plug removal

Each to his own and if you don’t drill you can’t make drill shavings or chips. The first 50 of these I changed used the hammer and punch method and that works as advertised. The next 50 or so I’ve drilled a hole and used a slide hammer. Put a dab of grease where you drilling to collect the chips and just barely penetrate the plug with the drill bit, don’t drill thru and stick the bit 2-3” inside the crank bore. Almost never see a chip inside the bore this way, but when I have it’s near the open forward end of the crank where it’s easily seen and removed.

Don Broussard
RV9 Rebuild in Progress
57 Pacer
 
You would not believe the dry oil crud in that hollow crank end! It took a while to get it all out and then clean it up so I could inspect it, but I found a perfect surface with no corrosion evidence at all. :D
Ed

Yep there is crud in all of them... I have pulled Constant Speed props and found crank ID had sludge in the inner bore a quarter inch thick... Glad it cleaned out nice for you, no corrosion. Cheers

+1 on drilling with care, grease on bit, vacuum, min penetration's, all good ideas.
 
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