Ed_Wischmeyer
Well Known Member
This was my second post-COVID flight to see if I was really recovered enough to fly, but that turned out not to be the issue.
Runup in the RV-9A was nominal, but wanting to beat traffic and not remembering that oil didn't warm up quickly in 50° weather, I took off before the oil was warm and oil pressure was high. We turned downwind to the crossing runway and as I retarded the throttle all the way on base, there were a few seconds of what my A&P/CFI in the right seat diagnosed as afterfire (fuel air mixture igniting in the exhaust system) and he heard what he thought was something coming loose. Mixture was probably leaned a little bit. I added a touch of power and all was fine again. Premature end of flight, but at least the plane was back in the hangar.
O-320, mags, carburetor adjusted to run rich for summertime cooling. Constant speed prop.
Hmmm:
* We added a gas two weeks before at another airport, but the plane ran fine on the flight back home from there, and it ran fine except for those few seconds.
* Mag check after we landed was nominal.
* Visual inspection of the intake and exhaust manifolds showed nothing.
* No evidence of spark plug blow by, as from a loose plug.
Did not inspect the carburetor linkages, and will do that tomorrow. Also, will inspect the exhaust system (crossover, no mufflers) for anything that might be hiding there.
Any ideas? Hypotheses? Seen it before?
Thanks!
Ed
Runup in the RV-9A was nominal, but wanting to beat traffic and not remembering that oil didn't warm up quickly in 50° weather, I took off before the oil was warm and oil pressure was high. We turned downwind to the crossing runway and as I retarded the throttle all the way on base, there were a few seconds of what my A&P/CFI in the right seat diagnosed as afterfire (fuel air mixture igniting in the exhaust system) and he heard what he thought was something coming loose. Mixture was probably leaned a little bit. I added a touch of power and all was fine again. Premature end of flight, but at least the plane was back in the hangar.
O-320, mags, carburetor adjusted to run rich for summertime cooling. Constant speed prop.
Hmmm:
* We added a gas two weeks before at another airport, but the plane ran fine on the flight back home from there, and it ran fine except for those few seconds.
* Mag check after we landed was nominal.
* Visual inspection of the intake and exhaust manifolds showed nothing.
* No evidence of spark plug blow by, as from a loose plug.
Did not inspect the carburetor linkages, and will do that tomorrow. Also, will inspect the exhaust system (crossover, no mufflers) for anything that might be hiding there.
Any ideas? Hypotheses? Seen it before?
Thanks!
Ed