Thanks in advance to all who respond. I'm a mechnical neophyte, bought a 1998 RV-6 a year ago, 120 hours on it since purchase (560 total time since built). This forum has been very helpful already with starter issues. Two new issues just arose, perhaps by sheer coincidence both in flights (#3-#5)shortly following installation of a new starter and vacuum pump, along with retiming and 2 new plugs. The engine is an IO-360-AIA with constant speed Hartzell prop.
1. After a completely normal start and run-up, 2nd flight of the day--the 4th flight following A&P installation the new components listed above--after bringing the rpm back to 1000, it started rythmically rising and falling, e.g. up to 1150, down to 990, up to 1130, down to 950, taking about 2-3 seconds for each rise, 2-3 seconds to fall. It flew fine without any noticeable surging during takeoff, cruise or in the landing pattern, paying attention to both sound & rpm gauge. The plane had been on the ground for 30 minutes following its 1st flight of the day with no issues (see point #2 below however). The same thing happened on the following runup, an hour later. Has anyone run into this issue? Is it a problem with the prop governor? Could dirty injectors be the culprit? Also please see the 'related consideration' at the bottom.
2. It may be coincidence, but starting with the flight before the surging issue, after one 'everything's fine' post-repair checkout flight and an uneventful flight home, during takeoff on every flight the oil pressure exceeds 100, which has never happened since I purchased the plane. I never take off without Oil TEMP at least 100. The oil pressure drops to below 100 within 5 seconds and during cruise is okay, upper 70s/lower 80s.
Related consideration: Wouldn't be complete without bringing up the mags also. Ever since I purchased the plane the left mag had consistently dropped 120, right mag 50. Plugs were cleaned, gapped, 2 changed without an impact. An A&P friend noticed the plane running rough (it had since day 1--and had previously been owned by an A&P) and offered to adjust the timing, which helped the roughness and brought the left mag drop to 110. After the new Skytec starter was installed--replacing an automotive starter--it was retimed and I was told the left mag had been off 3-5 degrees. In order to have all sparkplugs match (4 were 38E and 2 40E), I also had the mechanic install 2 new 38Es (bottom cylinders #2 & #4). Since then the mag drop has been worse and at the last flight the left dropped 160, right 50. Obviously something is not right and needs immediate attention. Plans are to clean the injectors, recheck the timing, and check the plugs.
And for what it's worth, a friend of the previous owner told me that the owner had 'always' complained about the plane backfiring. The original builder has passed away and the previous owner had it for hours 70-440. I experienced some ocassional backfiring and 'popping' in the landing pattern but found that more slowly retarding the throttle helped and it completely disappeared after the first retiming.
Thanks for taking the time to read this. I'm trying to climb a steep learning curve and appreciate your input. It's all very educational.
1. After a completely normal start and run-up, 2nd flight of the day--the 4th flight following A&P installation the new components listed above--after bringing the rpm back to 1000, it started rythmically rising and falling, e.g. up to 1150, down to 990, up to 1130, down to 950, taking about 2-3 seconds for each rise, 2-3 seconds to fall. It flew fine without any noticeable surging during takeoff, cruise or in the landing pattern, paying attention to both sound & rpm gauge. The plane had been on the ground for 30 minutes following its 1st flight of the day with no issues (see point #2 below however). The same thing happened on the following runup, an hour later. Has anyone run into this issue? Is it a problem with the prop governor? Could dirty injectors be the culprit? Also please see the 'related consideration' at the bottom.
2. It may be coincidence, but starting with the flight before the surging issue, after one 'everything's fine' post-repair checkout flight and an uneventful flight home, during takeoff on every flight the oil pressure exceeds 100, which has never happened since I purchased the plane. I never take off without Oil TEMP at least 100. The oil pressure drops to below 100 within 5 seconds and during cruise is okay, upper 70s/lower 80s.
Related consideration: Wouldn't be complete without bringing up the mags also. Ever since I purchased the plane the left mag had consistently dropped 120, right mag 50. Plugs were cleaned, gapped, 2 changed without an impact. An A&P friend noticed the plane running rough (it had since day 1--and had previously been owned by an A&P) and offered to adjust the timing, which helped the roughness and brought the left mag drop to 110. After the new Skytec starter was installed--replacing an automotive starter--it was retimed and I was told the left mag had been off 3-5 degrees. In order to have all sparkplugs match (4 were 38E and 2 40E), I also had the mechanic install 2 new 38Es (bottom cylinders #2 & #4). Since then the mag drop has been worse and at the last flight the left dropped 160, right 50. Obviously something is not right and needs immediate attention. Plans are to clean the injectors, recheck the timing, and check the plugs.
And for what it's worth, a friend of the previous owner told me that the owner had 'always' complained about the plane backfiring. The original builder has passed away and the previous owner had it for hours 70-440. I experienced some ocassional backfiring and 'popping' in the landing pattern but found that more slowly retarding the throttle helped and it completely disappeared after the first retiming.
Thanks for taking the time to read this. I'm trying to climb a steep learning curve and appreciate your input. It's all very educational.
