Last month I had an emergency with my C182 / Continental O470U. After take off and at about 3000 ft, I began to hear a loud noise in the cabin, and decided to land as quickly as posibly, that happend 17 minutes after take off. When the mechanic checked the airplane, he saw a fracture in the exaust tube of the 3rd cylinder, that was the cause of the loud noise, but also 4 of the 6 deck cylinder studs of the same cylinder were broken. Before this happened I had never experienced any power loss, wrong indications of oil or temperature. The mechanic made compression test and they were ok.

The engine had 373 hours from its overhaul, by Airmark Overhaul Inc. These people just said that the problem could be due to detonation, but all the parts, spark plugs, cylinders, etc were ok.

We are changing all of the cylinder deck studs, to be safe. I would like to ask if anybody had something similar happen to them?

I’ve been told this issue could be due to over-torque of the studs.

Sounds like a torque problem to me or studs installed wrong. I have a friend with a Mooney with IO360 Lycoming that had a cylinder come loose shortly after overhaul. It was decided that our other friend and mechanic that did the major overhaul didn't torque it right.

I've heard similar issues to what Marty mentioned: Something between the cylinder flange and the case like a sealant or something... it gets compressed, effective torque on the studs is reduced, they work loose, then start slamming like a slide hammer and the studs give up.

Sounds like it could be an under torque issue or detonated.
1. I would check the timing and that should tell you if you have a detonation issue. A timing shift advanced would certainly cause detonation.
2. Borescope that cylinder. Also if it was detonating that bad I wonder if the piston might be pitted? Or the head cracked. I guess if your changing studs then you will get a good look.
3. Make sure you do a soapy water bubble check when you do a compression check.
4. Torque check all the other base nuts and through studs.
Good luck!

Who did the overhaul and was the case sent out to be trued and line bored? Fretting of the case can cause the bolts to break.
DENNY

Put some pictures Jean Carlo.

Is that black permatex between barrel and case? I think they should be installed dry with only the o-ring in there. The permatex messes with the torque over time and bolts “loosen” up and then break. Looks like it can be saved though, to me the cylinder and valves look good.

Rod

Either someone forgot to torque them or their torque wrench was really out of calibration! Saw the same thing on an O-470R on a 182, and that's what we traced it to.
John

DENNY wrote:Who did the overhaul and was the case sent out to be trued and line bored? Fretting of the case can cause the bolts to break.
DENNY

Airmark did the overhaul, when I Asked the for the info on the case, they told me that they after 1 year they Put away the file that contains the info.

Had the same issue on a 182/180... under torque is what I figured... replaced and re-torqued the entire engine... has several hundred hours on it since...he might even chime in on this thread...

Of the engines I have been involved with that suffered detonation issues all they did was burn holes in the pistons and throw the resulting crap in the engine...

Brian

jeacarl wrote:

DENNY wrote:Who did the overhaul and was the case sent out to be trued and line bored? Fretting of the case can cause the bolts to break.

Airmark did the overhaul, when I Asked the for the info on the case, they told me that they after 1 year they Put away the file that contains the info.

I'm sure that no one is gonna put "did not torque cylinder hold-down nuts" in a logbook entry or work order.
Also doubt they would specify the torque value, even if the torking was noted.
But FWIW if they're a CRS, I believe they're required to keep their records for a specified period of time, and it's longer than a year.
But I'm not aware of any record-keeping requirements for a mechanic, signing off stuff as an A&P.