Where are they in valve sticking? They are suggesting via SB 338C or ? a time specific exhaust valve wobble test and if required a guide reaming. No Golden Parachute for some.
Gary
The major part of EX valve sticking has to do with lack of oil flow to both cool and lubricate the guide and stem.
A secondary issue is buildup of lead in the guide. This is more of an issue in low compression engines where the lack of oil flow has shows itself as the culprit with higher powered engines.
We should do a call out to those that have lived exclusively with Mogas, my experience was mostly with an O-200 which was Mogas only with a flawless experience. Glenn G has chimed in with a long and comfortable history with small Continentals.
Local people I know who have been dealing with sticking valves I have talked into hauling Mogas in, they are impressed how much better their plane runs.
This may not be for everyone and my experience for the most part was being one of the first to buy the STC back in the '80s. Today's auto fuel is not even close to the ASTM 439 that was originally specified in the beginning but there is nothing wrong with the fuel today as long as you keep the ethanol out.
The issue with ethanol has nothing to do with flight parameters but to do with the rubber and plastics used in our planes as well as any older vehicle. This pertains to hoses, diaphragms in fuel pumps and other soft parts in the fuel system.
You should look up what Ducati went through when it's fuel tanks swelled when the fuel changed, their replacement tanks failed just as quick, no clue how much that cost them.
In the race cars I build the fuel bladders were going stiff with a result of failing. At first the manufacturers changed to stupid short life cycles till the formulation of resins used was changed.
I am quite sure the bladders in aircraft would fail as well but most of them are feeding higher power non auto fuel eligible engines.
The SB 338C is just another, Their way of saying our engineers have once again F'ed up and you need to pay for it. I do not see that they have made any production changes to cure the issue.
Every batch of Lycoming crankshafts still need a material sample sent to an independent lab for material evaluation. So much for the problems being solved. There are not many companies forging the cranks and we have recently seen more cranks pulled from service.
Personally now that the Chinese are building a new Continental factory down south with a very clear statement that they are not intending to build the same product we have been living with. Get ready for a new line of heavy fuel engines for our use.
