cgmg
08-31-2004, 07:42 PM
I had posted earlier about my recent experience with having our 503 rebuilt, and all the problems we encountered. Well, the problems have come to an end.
I finally got the engine running well, EGT and CHT's where they belong. Had a problem with one of the carbs flooding itself, corrected that.
But Cathy was flying last week, and twice the machine shuddered with her, she said it felt like the whole back end fell off. She made it back to the airstrip, and landed with no more problems. I checked the machine out, everything was in place, and tight. Fired it up, started and ran ok, until I tried to prerotate. It felt like the prop hit something, twice, and the engine surged a couple of times. Had to quit for the night, too dark.
The next morning, checked the carbs out, one fuel bowl was lower than the other. Adjusted the float needle again, and fast taxied on the runway several times, no engine surges, or sharp knocks. Too windy to test a questionable engine, so went home. Finally, a week later, get to test fly the gyro. Everything ran ok, no surging, no sharp knocks, for 75 minutes.
Two nights later, I'm flying again, and waiting for Cathy to come up so she can practice again(I would not let her fly until I had 2 hours of no-incident running). After 40 minutes of flying, Cathy shows up, and I land. I taxi back to the hangar, re-fuel, and we get Cathy set up to fly. For some reason, don't ask me why, I spin the propeller while she is putting her helmet on.
The propeller spins freely in my hand, like it has a clutch. Only we have a B-gearbox, with no clutch! If I spin it right, I hear this funny rubbing noise occasionally. Now we know why the machine shuddered with her, and I felt what seemed like a rudder strike.
Tore the gearbox apart, and the small gear on the crankshaft is cracked clear through, and there's about a tooth and a half gone. The strengthening ribs on the inside of the case are torn up, and one is bent at a 45 degree angle, with a 1/4" section broken clear through. There's about a 1/4" high pile of metal shavings on the drain plug, and shavings all over the inside of the gearbox.
Call the guy who did the rebuild, and he finally admits it's most likely that he cracked the gear when he used his impact wrench to re-assemble the engine, after going through the gearbox, and reporting to me that it was all ok. Now this engine had 300 plus hours of gearbox trouble-free running prior to the engine rebuild, and his gearbox check-out for me. I have less than 14 hours running time since the rebuild. He has offered to rebuild the gearbox at his expense, but that's not going to happen.
When I got home, and Cathy and I discussed the situation, she raised a good point. How do we trust the engine, with all the problems I had getting it running properly after the rebuild work, and especially now that we know it's had several severe shocks to the crankshaft as the gearbox disintegrated? So we rebuild the gearbox, and fly again. We've already had two near misses and lived to fly again, will we be as lucky the next time? We have absolutely no faith in this engine or the gearbox, thanks to our rebuilder.
What we are doing is to quit flying with this engine. We are trading it in through the Rotax engine exchange program after we find out if I still have a job at the end of September. We'll buy a new gearbox with the engine. As far as the money we've already spent, we've probably lost that, as I doubt the guy will be interested in refunding all our money. I sent him an email tonight, telling him he won't be doing any more work for us, and why.
If I get cut at work, we won't be flying until I get a new job, and save the money back up to buy the engine.
Other than not using the same guy we did to do our rebuild, there is one other lesson someone else might learn from our experience. If I had taken the time to pull the drain plug after Cathy's problems, and my feeling of a sharp knock on the ground, I might have discovered the gearbox problem sooner. So if anyone else has something like this happen, take the 10 minutes to pull the drain plug. It may save you from an unplanned landing, a very expensive repair bill, or worse.
It really scares me to think I was about to let Cathy fly the machine again without really determining the cause of the shuddering.
I finally got the engine running well, EGT and CHT's where they belong. Had a problem with one of the carbs flooding itself, corrected that.
But Cathy was flying last week, and twice the machine shuddered with her, she said it felt like the whole back end fell off. She made it back to the airstrip, and landed with no more problems. I checked the machine out, everything was in place, and tight. Fired it up, started and ran ok, until I tried to prerotate. It felt like the prop hit something, twice, and the engine surged a couple of times. Had to quit for the night, too dark.
The next morning, checked the carbs out, one fuel bowl was lower than the other. Adjusted the float needle again, and fast taxied on the runway several times, no engine surges, or sharp knocks. Too windy to test a questionable engine, so went home. Finally, a week later, get to test fly the gyro. Everything ran ok, no surging, no sharp knocks, for 75 minutes.
Two nights later, I'm flying again, and waiting for Cathy to come up so she can practice again(I would not let her fly until I had 2 hours of no-incident running). After 40 minutes of flying, Cathy shows up, and I land. I taxi back to the hangar, re-fuel, and we get Cathy set up to fly. For some reason, don't ask me why, I spin the propeller while she is putting her helmet on.
The propeller spins freely in my hand, like it has a clutch. Only we have a B-gearbox, with no clutch! If I spin it right, I hear this funny rubbing noise occasionally. Now we know why the machine shuddered with her, and I felt what seemed like a rudder strike.
Tore the gearbox apart, and the small gear on the crankshaft is cracked clear through, and there's about a tooth and a half gone. The strengthening ribs on the inside of the case are torn up, and one is bent at a 45 degree angle, with a 1/4" section broken clear through. There's about a 1/4" high pile of metal shavings on the drain plug, and shavings all over the inside of the gearbox.
Call the guy who did the rebuild, and he finally admits it's most likely that he cracked the gear when he used his impact wrench to re-assemble the engine, after going through the gearbox, and reporting to me that it was all ok. Now this engine had 300 plus hours of gearbox trouble-free running prior to the engine rebuild, and his gearbox check-out for me. I have less than 14 hours running time since the rebuild. He has offered to rebuild the gearbox at his expense, but that's not going to happen.
When I got home, and Cathy and I discussed the situation, she raised a good point. How do we trust the engine, with all the problems I had getting it running properly after the rebuild work, and especially now that we know it's had several severe shocks to the crankshaft as the gearbox disintegrated? So we rebuild the gearbox, and fly again. We've already had two near misses and lived to fly again, will we be as lucky the next time? We have absolutely no faith in this engine or the gearbox, thanks to our rebuilder.
What we are doing is to quit flying with this engine. We are trading it in through the Rotax engine exchange program after we find out if I still have a job at the end of September. We'll buy a new gearbox with the engine. As far as the money we've already spent, we've probably lost that, as I doubt the guy will be interested in refunding all our money. I sent him an email tonight, telling him he won't be doing any more work for us, and why.
If I get cut at work, we won't be flying until I get a new job, and save the money back up to buy the engine.
Other than not using the same guy we did to do our rebuild, there is one other lesson someone else might learn from our experience. If I had taken the time to pull the drain plug after Cathy's problems, and my feeling of a sharp knock on the ground, I might have discovered the gearbox problem sooner. So if anyone else has something like this happen, take the 10 minutes to pull the drain plug. It may save you from an unplanned landing, a very expensive repair bill, or worse.
It really scares me to think I was about to let Cathy fly the machine again without really determining the cause of the shuddering.