Engine catastrophe in flight today

[Guest]

I want to thank everyone that responded to this post.  I feel like I was clearly emotional about it yesterday, and it was for that reason I did not put the overhaul shops name on here.  Hopefully I have not trashed anyone at this point, because as some have said that is really unfair at this point until more is known.  Looking at my engine log from when the new (overhauled engine) was installed it has two entries that concern me.  The engine was done as stated in 01/09.  In April of 2011 the #4 cylinder (the one that is dead now) was "repaired" for oil blow by. This repair was done by the original shop that did the overhaul (someone said it was a field overhaul if I gave that impression it was wrong it was done by a "national" shop). The newly repaired cylinder was replaced and signed off on.  At annual in 2014 (February) the compressions were as follows #1 73 #2 72 #3 76 and #4 64.  While I know that 64 is within tolerance it concerns me that this same cylinder is causing the problems again yesterday.  I think what I am going to do is just go with a brand new cylinder and have all the checks done to make sure it is not more than that.  If the original shop wants to help great if not so be it.  At least I will feel better about it going forward.  From what I have learned so far I guess I did ok landing with 2 1/2 quarts of oil left as far as Lycoming is concerned, but it was really an interesting experience.  Again thank you all for your opinions I am clearly not an expert at this!!

Mike,

You won't regret choosing a new cylinder assembly. Be sure to have the installing shop verify that cylinder number 3 was not honed out to 0.010" oversize (common in re-used cylinder assemblies) If it was you will be buying 2 cylinder assemblies as Lycoming does not allow oversized pistons and cylinders on opposite sides.

Clarence

[82Mike]

Thanks Clarence I am asking about that now

[philiplane]

Large and sudden oil loss from a single cylinder is rarely a simple ring problem. It is usually a hole in the piston, caused by pre-igntion. You can have broken ring lands from detonation, but even so, the oil loss will be much slower. Holes in the piston crown cause compression to go straight to the crankcase, where it blasts out the breather, taking your oil along with it. This can empty an 8 quart pan in a matter of 15 minutes.

 

Other possibilities are a broken-off valve head, which again, punches a hole in the piston with the same results.

 

Broken valve heads occur when people re-use exhaust valves (even though they are required to be replaced at overhaul) instead of installing new ones. 

Detonation occurs due to ignition & fuel system problems in combination.

Pre-igntiion occurs from faulty Slick magnetos that have jumped internal timing or cracked distributor blocks, or burned distributor blocks from high resistance Champion spark plugs, or from Champion fine-wire spark plugs with broken nose insulators.

 

The only one of these an improper overhaul could have directly caused is the re-use of old exhaust valves. 

[82Mike]

The problem is a broken piston ring?

[KSMooniac]

Could be... hone the cylinder, install new rings, break-in and enjoy.  Hopefully that is all you have going on!

[82Mike]

No I have a picture of it now. It is a broken ring.