Lycoming AD

210TC · Post by **210TC** » Tue Sep 04, 2007 3:01 pm

http://www.lycoming.com/support/publica ... SB569A.pdf

http://www.avweb.com/cgi-bin/texis/scri ... &x=32&y=10[/quote]

http://www.avweb.com/cgi-bin/texis/scri ... g&x=32&y=7

Green Hornet · Post by **Green Hornet** » Tue Sep 04, 2007 6:18 pm

210TC, thanks for the links. The engine was removed today and will be split by tomorrow. I'll get the crank shaft SN # and do my due diligence. In past 2 annuals the engine SN # was not on the list of of the SB. I am just hoping that the crank is not damaged or one mfg. with the alloy mix that has been recalled. I may still have to replace bearings along with the cam/lifters. I find it difficult to comprehend that only 960 hrs the cam is peeling metal? Believe me when I tell you this aircraft was & is well taken care of by all the owners. I am a retired Quality professional so I always seek out root cause. So far the speculation as to root cause are not comforting. I would really like to get a failure analysis on the cam after it is removed.
Thanks Again,
Bill

210TC · Post by **210TC** » Tue Sep 04, 2007 7:15 pm

Please post pic's of your cam and lifters.......We would all like to see.

210TC · Post by **210TC** » Wed Sep 05, 2007 3:07 pm

Sojorrn's lifter and cam. It appears that metal traveled throughout the oil galleries, damaging the bearings.

Green Hornet · Post by **Green Hornet** » Wed Sep 05, 2007 3:22 pm

David,
Thanks for posting the 2 clear photo's I will try to get some more but these pretty much tell the story. All 4 tappets exhibit the same pitting and the cam lobes (2) are peeling metal as well as pitting. We will replace the 4 tappets, all lifters, and cams. The engine specialist said the lobes are the culprits.
The good news is the crank shaft is not from the bad batch from SB 569A and is in good shape. Although the bearings will need replacing since the casing around the bearing exhibits damage.
Root cause is still an open question for me. Why would the metal on the lobes peel after only 960 hours?

a64pilot · Post by **a64pilot** » Wed Sep 05, 2007 6:10 pm

Unfortunately the cam and tappets is about the highest "loaded" part in any engine. All it takes is a small defect, scratch or corrosion on either to start wearing both of them at a high rate. I've seen engines completely destroyed from the metal that ate the bearings out.
What is the deal with the new roller tappets from Lycoming? Is that certified for your engine?

Green Hornet · Post by **Green Hornet** » Wed Sep 05, 2007 6:18 pm

I am the wrong person to ask about the roller tappets but they are original equipment for the 1997 LYC as far as my logs state. So I am assuming they are certified?

maules.com · Post by **maules.com** » Wed Sep 05, 2007 9:55 pm

Roller tappets are certified and in present production Lycomings if so identified. I understand Maule is getting them for new production.

One culprit for premature lobe wear is using oil without the additive specified in Lycs bulletins which is also in Exxon Elite and Aeroshell Plus oils. It helps the oil stay on the shiny surfaces inside the engine when hot after shutdown, thus giving some protection at next startup even if it is a week or more.
There is moisture in the cooling crankcase which rises to the shiny surfaces which if not protected, can settle, causing corrosion, thus the need for regular oil changes, to help eliminate these moistures and acids or a dry air pump can be used to help.
The camshaft on a Lyc is on top of the engine and so not bathed in oil. At startup when cold there is no oil pumped to the lobes so it must be splashed up there and when the oil is thick, this takes a while and if idled after startup, no oil gets there for a while.

a64pilot · Post by **a64pilot** » Thu Sep 06, 2007 4:15 am

That is not a roller tappet in that picture. Unless I'm nuts roller tappets have a big roller on the surface that contacts the cam. I think the rollers are relatively a new thing. I feel pretty sure they were not OEM in a 97 engine. If possible, I would put a roller cam and tappets in at overhaul.

Green Hornet · Post by **Green Hornet** » Thu Sep 06, 2007 5:30 am

The engine has been getting AeroShell W100 Plus for several years. How about Engine oil additive for Lycoming 0-320 H engines. One bottle to be added at each oil change. Must be replenished at 50 hour intervals if oil change period exceeds 50 hours. I have a 540 ? or is this over kill?
or Marvel Mystery Oil 32 oz ?- Standard for break-in on new or overhauled engines, carbon removal from cylinder heads, piston rings, valves, etc. Mix with regular oil for perfect engine operation temperatures to -20° F. Lubricates tight nuts, control hinges and landing gear. Dust does not adhere readily. 1 Quart.

210TC · Post by **210TC** » Thu Sep 06, 2007 11:08 am

Sojorrn,
I just had lunch with someone whom has sent the cam and lifters out for complete metallurgical profile. His company wanted to manufacture new cams and lifters. They found that Lycoming had used the finist metals available.
He said the roller cam is no better against rust.
He stated the same as Jeremy, The cam sets in a place that makes it highly vulnerable for rust. His company does not use the oil additive ,nor do I. This is not a recomendation (about additive).
Lycoming just made a boo boo in the location of the camshaft.

http://www.cessnapilotsassociationofaus ... ticle.html

210TC · Post by **210TC** » Thu Sep 06, 2007 12:36 pm

I think it would be worth a quick email to lycoming with your crank serial #, just in case. Who knows, they could expand this issue to include your #??????????????????? at any time.

a64pilot · Post by **a64pilot** » Thu Sep 06, 2007 1:24 pm

I'll admit to putting Marvel Mystery oil in every now and again and flying for an hour just prior to an oil change. Normally I do not recommend adding anything to oil, I do not believe in additives unless the manufacturer recommends it.

a64pilot · Post by **a64pilot** » Thu Sep 06, 2007 1:39 pm

The best thing you can do to combat internal engine corrosion is to fly it every week. If you can't fly it, get someone else to. Time and time again I see abused beat to death ramp tramp rental trainers make it to TBO, while the Dr's pristine, pampered airplane doesn't.

Green Hornet · Post by **Green Hornet** » Thu Sep 06, 2007 4:25 pm

Let me Vent!
Well all I can say is that 251TT was previously owned by a commercial jet jockey, a Doctor (God Knows they didn't fly it every week) and now an old fart that didn't fly it every week. God knows I tried but either the weather or some other crap got in my way. However since I am pouring more $$ into her I will fly her once a week even if it is just around the patch. I was under the mistaken impression that 115 hours for the first year was avearage?
Nevertheless from a quality point of view the engine design was not well thought out. I guess the design review, DOE application meeting wasn't called? Pesky design review meetings- why do it right the first time when it can be done over and over again?
In the semiconductor Industry if an application could impact human life it was Class S (Space level) and Govt source inspected from design to finshed product never mind a locked BOM (Build of Materials). The crankshaft recall SB569A speaks volumes- change the design via alloy mix . I would like to see the reliability #'s on that ECN.
Why is it always Pilot error? AH! I feel much better

GA seems to lean on inspection rather than process control. With any luck Toyota will make a SEL airplane engine before I go broke.
I got to go I just got an AD from Lycoming in the mail I have to read

Lycoming AD

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