So my knowledgeable friends, my TB20 is having its annual and the engineer reports that cylinder number 5 of my plane’s engine is showing 45-50 psi “at best”. Certified limit is 65/80 apparently.
Do I:
1) inspect the engine myself before authorising any work (they have invited me to do so – I wouldn’t know if what they were showing me proved that an overhaul / new cylinder was warranted….
or
2) ask for the cylinder to be overhauled?
or
3) Ask for the cylinder to be replaced at a cost of 50% more than an overhaul?
The engine is “on condition” – more than 12 years old. I don’t remember the hours, but perhaps 600 or 700 is correct. I think a cylinder or two have been replaced before by the previous owner.
All advice welcome.
Thanks
Howard
Sounds like overreaction. Ask them to determine if the leakage is past the rings or past the valves. Ask them to do a borescope inpection of that cylinder. Then take the next step afterwards.
Watch this… came out just a couple of days ago…
Thanks bosco…Your advice is well received.
Sadly, I can’t watch Mike Busch videos because he takes 45 minutes to say what other would say in 5 and I end up shouting at my computer….and then stopping his videos. He’s a hugely well respected and brilliant engineer but I find him to be a rather lousy, boring, long-winded presenter, sadly. I find that life’s simply too short to listen to him. I wish it wasn’t.
He story is over after minute 20…
It fit so well, because the case is similar to yours…
ok,…so I watched it on fast-forward. Thanks
That Mike Busch video is about oil pressure but the message is totally valid on “Rushing to Judgement”. He has done a specific video about compressions and, from memory, he mentioned that there is new Lycoming guidance which is something like this:-
Now that borescopes can show so much detail there has been a shift in the last few years even by the Engine manufacturers.
I totally agree about the Mike Busch videos, if he wants to make them that long he should just put more examples in. They are, however, a really good source of useful information.
Thanks Howard for putting into words my exact feelings about Mike Busch.
It seems to be the way with American experts, I don’t doubt what it hey have to say is valid but snappy presentation seems not to be their strong suit. I watched a presentation on the Piper wing spar problems and the presenters could have said all there was to say in 25% of the time.
So I have an update: Cylinder number 5’s compression issues relate to a leaking exhaust valve and the worst reading the engineer got was 20/80, and the best (when he told me that he did something with oil that I didn’t understand) was 50/80. He used to be a consulting engineer for Continental apparently. He knows engines. He says he could lap the valve, but he wouldn’t recommend it. He recommends either sending the cylinder away for a complete overhaul, or buying a new cylinder.
The engine has 650 hours on it and is 14 years old. Two years ago the inlet valve on this cylinder number 5 was lapped.
All opinions as to what to do: lap, overhaul, or replace, gratefully received. I fly 30-50 hours each year…when my plane is not in the shop. A good number of flights are over water. Some touring flights are 3 hours.
Tricky as you are already over the barrel. Some food for thought on the subject from guess who..
https://www.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2013-07_compression-in-context.pdf local copy
If there are no hotspots which should be the case as he says he could lap the valve then it should look ok in the boroscope. maybe it could get a second chance, unitl next time fine tune your leaning technique.
