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Oil leak from a through bolt.

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Re: Oil leak from a through bolt.

Postby diablo » Wed Nov 06, 2019 9:50 am

Good to hear yo got to the bottom of it Clive.

As you can appreciate, there is nothing better than eye balling very carefully. It obviously fooled you and your mechanic for a good while.

This is a first one for me. Cylinder cracks are pretty rare but not unheard of. There have been cases of wrong nuts causing stress on cylinder base (looks like that is what did yours). Are you sure that when you rebuilt engine (1000 hours) correct nuts and new thru bolts were used ? a big flange on cylinder nuts would cause just that and it is documented on build guide ! I think it is weird it was not detected before. However, the presence of sealer as mentioned would not have helped (may have masked problem). It should have been pretty easy to spot with some engineers blue ...

BTW, your honing also looks a little weird. The honing pattern specified is a Cross Hatch (see image). Yours seems to be straight ...

1425302361_cross-hatch-correct.jpg
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Re: Oil leak from a through bolt.

Postby Clive » Wed Nov 06, 2019 8:02 pm

Hi Dean, The barrels are pretty much done and it was just a quick glaze bust and not too much as they are almost out of spec. The straight pattern is wear, that is if you eye ball it carefully. ;)
Just an interim tart up until the new barrels become available. To be honest I was looking more at the other end where they were worn the most.

The 1000hr was just a top end, I didn't do it I was working away and paid Southery, can't remember what was changed but the bolts and the barrels weren't, the nuts were radiused for sure, I do remember all the hot air about that. I'll check the eye watering bill.

The reason for the crack is not surprising, we had a bolt snap about 150 hrs ago when the plane was being used for training by two pilots. Might be rare but Roger guessed it straight away. Don't know how long we were flying on three bolts but the crack is adjacent to the bottom bolt that didn't crack so it took all the load. The engine ran fine just a load of oil out the bottom which sent me looking for a problem. Fitted a new set of the 3/8" bolts and the tall nuts, that's when I found the worn valve top, rattling in the collets.
That bit was all fine and I was in two minds to just refit them but I thought I'd do the bottom end now so the barrels and pistons is a quick job when the parts are available.

Regards, Clive
P.S. can you approve Chris to the board
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Re: Oil leak from a through bolt.

Postby diablo » Fri Nov 08, 2019 4:44 pm

I can see a little cross hatching but a lot of what looks like pretty straight lines going around the bore. From here, it does not look like wear but I suppose it needs a betted butchers :shock: :lol:

Roger has been off the scene for a long while. I have not heard anything anywhere about Roger since he moved to in France. If i remember correctly, his company was registered at an Estate Agents near my side of town which I thought was rather odd (see link).

http://www.jabiruownersgroup.org/viewtopic.php?f=24&t=807

So, is he back on the scene ? Is he still in France ?

I have spoken to Kevin on a few occasions. He seems like a pretty serious and knowledgeable chap. I dont really know the other chap (older guy .. marshal ?? ) but my inspector does. He was not registered as a LAA inspector so probably worth staying with someone that is registered with the LAA as it avoids any complications and issues with getting things approved.

John Cook and Bob Boyle of the LAA are great. Bob is the LAAs inspector of Inspectors and has all of the contacts within the LAA so it is much easier to things done. BTW, I am also on the way to getting my ticket. Still a way to go, but with a bit of hard work and the never ending passion for flight and flying machines, one day, i may be issuing permits.
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Re: Oil leak from a through bolt.

Postby Clive » Sat Nov 09, 2019 12:07 pm

Roger has retired but I've stayed in touch.

Kevin has been great and runs a tight ship and knows his stuff. Very handy guy for the Jabiru community. Good luck with your ticket, I have to admit I've enjoyed the investigation work even though it took a while. She's running lovely now, almost time to hand it over to Chris, it will be at Popham near his new home.
Regards Clive
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