Be nervous or not? Rotax 912 O'Ring Failure
So here is what happen. Departed the airport to head over to our test block area. About 15 miles from the airport start to smell oil, look over at oil pressure and its at 45 PSI. Immediately turn back towards the airport, reduce power down to 4900 RPM. On final the oil pressure is now 30 PSI, just over the numbers throttle reduced to Idle the oil pressure drops to below 20 PSI. Taxi back to parking shut down engine, oil running everywhere out the bottom of the cowling. Removed cowling and found that the front left cylinder aft push rod tube O'ring had failed. Heads were off to due a piston change and the o'ring got pinched putting it back together. Weird thing is that we have flown 8 hours before it finally blew. Drained the remaining oil out of the oil tank and the engine sump and had approx. 2 1/2 quarts left between the two. Our kitfox is Tricycle gear on the level in the sump would be even through the entire engine not like if it were a tail dragger and the oil would naturally pool at the back of the engine. Called Mississippi Light Aircraft, they do Rotax overhaul and they suggested replacing the o'ring run the engine for about 15 mins, then remove and check the oil filter, if no brass or metal run the engine for an additional 45 mins at low power. They said if your going to through a rod it will happen within the first hour of running. With as much oil as was left in the sump I can only assume that the crank was still bathed in oil and that the oil pump was still moving oil, even though there was on oil pressure due to the fact the case couldn't build up the pressure due to the o'ring. So should I be real nervous or not?
Reply With Quote
