retailguy
Line Up and Wait
Cross posted to Beechtalk...
Need some advice and suggestions here.
Basics:
1961 Beechcraft Travel Air (Left Engine if that matters)
IO-360 B1B - converted to Bendix fuel injection in 2009.
1997 overhaul - ~900 hours, no cylinders have been off plane since overhaul.
chrome cylinders, iron rings.
quick backstory. Flew this plane 70 hours from January until April when it went in for annual. Probably put a quart of oil in each 10 hours of flight but was so insignificant none of us really tracked it.
Coming out of annual it has used a quart of oil consistently about every 3 or 4 hours. It has done this for 50 hours since June 1st when we got it back after annual and some avionics upgrades.
Yesterday, we pulled the 4 lower spark plugs. 3 had carbon deposits, no sign of oil. One, (cylinder #3), was wet, and showed carbon deposits as well. At that time we didn't take the top plugs out and began to suspect that the oil control ring was stuck or broken.
This morning we flew about 50 miles to a friends hangar who had a boroscope and some compression equipment. Took the top plug out of cylinder and found it dry with no sign of oil at all. Needless to say we were surprised. With the kind of oil consumption we have, we expected it to be wet, it wasn't, and didn't look like it had ever been wet.
Compression check - 78/80.
Pulled other three top plugs at that point. No issues. All 4 looked identical, no carbon deposits, no oil, exactly as you'd expect plugs to look.
Boroscope on cylinder #3 was unremarkable. No scoring, no obvious issues anywhere. Looked perfectly normal.
What we know:
- consistent oil consumption
- oil on underside of wing behind exhaust pipes and oil breather
(cleaned it off, back 12 hours later)
- no oil smoke on startup
- runs well, no issues with performance
- We changed the oil ourselves 12 hours ago, did not have it analyzed, did not find anything in oil or filter.
Thoughts as to what we should do next?
Need some advice and suggestions here.
Basics:
1961 Beechcraft Travel Air (Left Engine if that matters)
IO-360 B1B - converted to Bendix fuel injection in 2009.
1997 overhaul - ~900 hours, no cylinders have been off plane since overhaul.
chrome cylinders, iron rings.
quick backstory. Flew this plane 70 hours from January until April when it went in for annual. Probably put a quart of oil in each 10 hours of flight but was so insignificant none of us really tracked it.
Coming out of annual it has used a quart of oil consistently about every 3 or 4 hours. It has done this for 50 hours since June 1st when we got it back after annual and some avionics upgrades.
Yesterday, we pulled the 4 lower spark plugs. 3 had carbon deposits, no sign of oil. One, (cylinder #3), was wet, and showed carbon deposits as well. At that time we didn't take the top plugs out and began to suspect that the oil control ring was stuck or broken.
This morning we flew about 50 miles to a friends hangar who had a boroscope and some compression equipment. Took the top plug out of cylinder and found it dry with no sign of oil at all. Needless to say we were surprised. With the kind of oil consumption we have, we expected it to be wet, it wasn't, and didn't look like it had ever been wet.
Compression check - 78/80.
Pulled other three top plugs at that point. No issues. All 4 looked identical, no carbon deposits, no oil, exactly as you'd expect plugs to look.
Boroscope on cylinder #3 was unremarkable. No scoring, no obvious issues anywhere. Looked perfectly normal.
What we know:
- consistent oil consumption
- oil on underside of wing behind exhaust pipes and oil breather
(cleaned it off, back 12 hours later)
- no oil smoke on startup
- runs well, no issues with performance
- We changed the oil ourselves 12 hours ago, did not have it analyzed, did not find anything in oil or filter.
Thoughts as to what we should do next?