There have been some RV-12s built with Viking 110 engines, so I just wanted to post some news on this engine here.
In the last 6 months there have been 2 in flight fatigue failures of the gearbox input drive flange ears, one each on 2 different aircraft. One failed at 130 hours total, the second failed at approximately 800 hours. I am attaching a picture showing the fatigue crack on the 800 hour engine where the drive ear departed the airframe after tearing apart the radiator and cooling tube on the side of the engine.
Both failures occurred during take off. one caused the total loss of the airplane, the second the pilot was able to do a 180 and downwind landing on the same runway used for take off. Both had the potential to be fatal accidents, it was just a question of how high above ground the airplane was able to get prior to failure.
If you have one of these engines, PLEASE remove the gearbox and inspect both drive flanges for fatigue cracks. Dye penetrant will find even small cracks. Al that is needed is a new centering bushing from Viking so that the gearbox is properly located when it is put back on.
If you inspect your drive flanges and do find cracks, inform the factory, you will need to get replacement parts. Replacing the flange on the flywheel side is pretty simple but for the pressed on gearbox input flange you may want to ship it back to Viking to get replaced. I'm assuming none of the replacement parts will be free, but if quite a few are needed Viking will be able to make a bigger batch which may save some money. Viking is claiming that only engines that did not comply with the flywheel and drive flange AD are at risk, but based on my investigation the failure at 130 hours was in full compliance with all the correct parts. I would suggest better safe than sorry. Im pretty sure the centering bushing does not cost much if indeed your parts turn out to be fine.
Be careful out there...
Keith Olivier
In the last 6 months there have been 2 in flight fatigue failures of the gearbox input drive flange ears, one each on 2 different aircraft. One failed at 130 hours total, the second failed at approximately 800 hours. I am attaching a picture showing the fatigue crack on the 800 hour engine where the drive ear departed the airframe after tearing apart the radiator and cooling tube on the side of the engine.
Both failures occurred during take off. one caused the total loss of the airplane, the second the pilot was able to do a 180 and downwind landing on the same runway used for take off. Both had the potential to be fatal accidents, it was just a question of how high above ground the airplane was able to get prior to failure.
If you have one of these engines, PLEASE remove the gearbox and inspect both drive flanges for fatigue cracks. Dye penetrant will find even small cracks. Al that is needed is a new centering bushing from Viking so that the gearbox is properly located when it is put back on.
If you inspect your drive flanges and do find cracks, inform the factory, you will need to get replacement parts. Replacing the flange on the flywheel side is pretty simple but for the pressed on gearbox input flange you may want to ship it back to Viking to get replaced. I'm assuming none of the replacement parts will be free, but if quite a few are needed Viking will be able to make a bigger batch which may save some money. Viking is claiming that only engines that did not comply with the flywheel and drive flange AD are at risk, but based on my investigation the failure at 130 hours was in full compliance with all the correct parts. I would suggest better safe than sorry. Im pretty sure the centering bushing does not cost much if indeed your parts turn out to be fine.
Be careful out there...
Keith Olivier