I just got my plane back from Annual, It ran perfectly beforehand and no squawks going in.
(A little history ... Converted the engine to Ovation 3 (310hp) at last annual – Only engine change required is increasing prop governor speed and increasing fuel flow. Anyway as I said it ran perfectly for a whole year.)
Nothing was found to be an issue during annual except the Spark plugs were apparently out of tolerance and replaced. They ran engine afterwards and everything was OK.
Went down today to fly it for the first time since signed off a couple days ago. Engine running rough. #1 cylinder not making power. They checked it out and thought fuel injector nozzle to cylinder #1 was getting plugged (as part of the annual they ultrasonically cleaned all injectors). Recleaned the injector put back together. The issue then changed to Cylinder #2, Repeated the process, Recleaned put back together. The issue change to Cylinder #3, Repeated the process, Recleaned put back together. The issue changed back to Cylinder #1, - They tried with the old plugs back in; They rechecked magneto timing - no change. (BTW The Magneto is hundreds of hours away from it’s 500hr overhaul)
They disconnected and checked the fuel going to each cylinder using the fuel pump and reported has debris?? They think a gasket or something might be disintegrating in the Fuel manifold that sits atop the engine. That’s as far as they got today. (BTW The spark plugs were changed from Champion fine wire to Tempest, but they’re convinced it’s the fuel side of combustion that’s causing the problem.)
Questions:
1) Is this just incredibly bad and coincidental timing – (first time check out after annual – running fine beforehand) or could it be related to annual. To my knowledge the only part of the annual that involves the fuel system is cleaning the fuel screens and Injectors.
2) Does it make sense to jump from Cylinder to cylinder?
3) Any other thoughts as to cause, or what’s gone on would be appreciated
Thanks in advance
Roger