- Apr 5, 2019
. Click above on "Toobuilder post " to see complete replyEarly top OH and cam changes in Lycomings are almost certainly a result of operator error. Treated properly, cooled adequately and flown often, a Lycoming will go WAY past TBO with nothing more than routine oil changes.
Reply: Agree . There is a whole industry built around supplying replacement cylinders. So early replacement is a major consideration to owners of aircraft engines. No real data check on my part, but would hazard a guess that 30/50% of owners do actually replace at least one cylinder prior to TBO no matter what type of airplane the engine is in. I think the biggest key is regular use.
[QUOTE="Toobuilder, post: 487108, member: 6803"
There is also nothing wrong with installing a good used cylinder (or a whole set) to replace bad ones. Just so long as it's documented as a"repair" and not an "overhaul".
Reply: Agree. My point, which I didn't make very well was that in order to save money, an individual might purchase a used cylinder and install it on a certified airplane himself and put no entry in the log book. Definitely illegal Maybe he just wants to sell the airplane and figures he can do an adequate job.........no harm/no foul as far as he is concerned. Big Trouble if anyone finds out though. I have seen things like that.
Going to the homebuilt/noncertified.Same guy, same engine, experimental airplane. Same guy does the same thing to same engine with same cylinder.......but does not tell the AP who performed the last inspection. He also doesn't record it in the non-required engine log book even though he uses that for documentation. Engine is running fine at yearly inspection and everything appears normal as it did when the AP performed last years inspection. The fly in the ointment here is that used cylinder was one that was replaced because of a factory defect. It sat on a shelf in a corner and was forgotten. The owner of the cylinder(s) passes away and his heir has an estate sale to get rid of all those old aircraft parts that were in the shop. Someone buys them and they look like they are good cylinders wear wise, so he sells them on Craigslist. No one is aware that this cylinder has a defect, and it gets installed on the experimental engine. Compression tests are normal.
In this case, no one did anything illegal, and money was saved.......tick...tick...tick
What you said is correct, but with thousands of used engines in not just RVs, but other types of homebuilts as well, I'm reasonably confident that there are a lot of decisions made relative to engine maintenance where money causes less than optimal decisions to be made. Its true that it takes a lot more effort to adapt an alternative engine. A successful conversion places the owner/builder in a position where he can deal with any problems himself and usually at a very reasonable cost. What I would like to see here on this thread is a bunch of knowledgeable people discuss with the OP possible ways to make his project work for him rather than just tell him it won't work. When the variable cam timing was introduced, its purpose was to increase economy and help with emission control. Then the hot rod industry got involved and found ways to actually make it help produce more HP (or was it Torque). So maybe instead of saying it won't work well, and just attacking that....maybe we might encourage him to try and keep us posted on his results. Its not like he can't disable or remove it if it doesn't test out well for him.