We own an ultralight aircraft Sova (nowadays named Skyleader) with a Rotax 912ULS engine dated 2003. Since new we ensure that all advisable maintenance has been undertaken by a local Rotax mechanic professional.
About three years ago in the 1250h inspection it was detected a slightly “out of roundness” deviation on the crankshaft and since then every 50h inspection maintenance a measure on the crankshaft journal has been done accordingly to Rotax “Crankshaft Out-of-Roundness Inspection” procedure.
The measures done were as follows:
Ago 2015 - 1250h: 0,10mm
Mar 2017 - 1300h: 0,09mm
Set 2018 - 1350h: 0,11mm
Through all its life time there were no propeller strike or any kind of crankshaft effort event. We even doubt if it’s recommend to perform this measure even if there’s no special strike event that leads to this procedure. The engine always preform very well, keeping good compression ratios.
Anyway the fact is that we found these measures and with this scenario, we would like to get some opinion in what would be the advisable action, if any, in order to have confidence in the engine operation concerning this issue.
Thus, we face these following options:
- Can we stay comfortable and carry on operating the engine as it is and keep just measuring it on a 50h inspection basis?
- Should be better to disassembling the crankshaft and have it measured on all its parts?
- Should we need to replace the crankshaft?
- Should we replace the engine?
We also have it operating for 15 years which we believe has reach the TBO age condition and is not too far from the 1500h TBO as well.
We would much appreciate your comments on this issue.
About three years ago in the 1250h inspection it was detected a slightly “out of roundness” deviation on the crankshaft and since then every 50h inspection maintenance a measure on the crankshaft journal has been done accordingly to Rotax “Crankshaft Out-of-Roundness Inspection” procedure.
The measures done were as follows:
Ago 2015 - 1250h: 0,10mm
Mar 2017 - 1300h: 0,09mm
Set 2018 - 1350h: 0,11mm
Through all its life time there were no propeller strike or any kind of crankshaft effort event. We even doubt if it’s recommend to perform this measure even if there’s no special strike event that leads to this procedure. The engine always preform very well, keeping good compression ratios.
Anyway the fact is that we found these measures and with this scenario, we would like to get some opinion in what would be the advisable action, if any, in order to have confidence in the engine operation concerning this issue.
Thus, we face these following options:
- Can we stay comfortable and carry on operating the engine as it is and keep just measuring it on a 50h inspection basis?
- Should be better to disassembling the crankshaft and have it measured on all its parts?
- Should we need to replace the crankshaft?
- Should we replace the engine?
We also have it operating for 15 years which we believe has reach the TBO age condition and is not too far from the 1500h TBO as well.
We would much appreciate your comments on this issue.
