Oil Pressure failure

RGaines · #1 11-04-2009, 09:37 PM

I was flying today and had an oil pressure alarm in the -12. Dynon alarm went off and oil pressure was zero. I was over a local field at 2,000 and did a precautionary landing at idle. Oil temp did not increase. On the ground there was lots of oil in the sump. I had been aloft for about 30 minutes. I burped the engine and there was the same quantity that I left with. No engine oil in the engine compartment and everything was in place and dry. electrical connections were heat srinked and solid. I started it again and had oil pressure but the engine stopped because I didn't have enough throttle open. Restarted and zero oil pressure and shut down. I got a ride home from a local A&P friend. Nobody around knows anything about rotax engines so the next step is completely unknown. I called van's and the help desk line was busy and went to the operator and then they were closed.

Any long time rotax users have any ideas? It seems to me that when the engine burps that the engine driven pump must be working working. So a sender issue? Very disappointing for a 12 hr old engine.

I will be calling van's in the am but I don't think they have much experience with this engine past the design phase. Raises big questions about sophisticated electronic systems without a wiring diagram.

JBPILOT · #2 11-04-2009, 09:49 PM

I'd check the wire from the sender where we had to cut the wire off and put ends on it and the wires from the harness. I'd check those first. Would be easy to have a bad crimp or loose connection there would be my first guess.

John Bender

badmrb · #3 11-04-2009, 10:58 PM

I had something similar happen on a trip in a Zodiac 601HD with subaru while crossing western Kansas for CO. Oil pressure kept dropping. . .I kept pulling power and headed for nearest airport. . .just waiting for motor to seize. Little town did have a parts store but not the right sender unit.

I ended up using a $15 mechanical guage they had. It showed good pressure. I taped it under the dash. Flew over the airport until I felt confident it was just a bad guage and continued on. Now if there had really been no oil pressure, different story.

Skybolt Al · #4 11-04-2009, 11:02 PM

I rent a Remos G-3 (Rotax 912) regularly and there are always problems with false readings with the oil temp, and egt on the Dynon. The FBO is always getting the senders replaced but they don't seem to last very long before they malfunction again. The engine seems to be pretty bullet proof.

Jeromiemead · #5 11-04-2009, 11:39 PM

Don't sweat it. If the integrity of the wiring is good from the sending unit to the dynon then you most likley have a bad sending unit on the motor. This is "common". Not a high failure rate but they do die occasionally. Replaced a lot of them over the years. best way to verify this is to tee in a mechanical test gauge with the sending unit and run the motor on the ground (tie the plane so you can run it at higher rpm). verify the problem is the sending unit and not the motor. I HIGHLY doubt it is the motor. One thing to remember is the oil pump sucks the oil from the tank like sucking thru a straw, a long straw so if you show a oil pressure issue in the engine check here first. One last thing, if you need a new sending unit and it is not covered under warranty you will find that it is a VERY exspensive part from Rotax but we have a solution. The same part from another supplier for a good price. I will post it when I get to the office in the morning.

turbo · #6 11-05-2009, 05:36 AM

i like a direct mechanical oil pressure guage on my lyc. very dependable. does rotax have one of those? prblem solved.

Geico266 · #7 11-05-2009, 07:17 AM

Good advice from all. It's not the engine.

David-aviator · #8 11-05-2009, 08:26 AM

Another way to know if pressure is lost is to use Van's oil pressure switch (IE SPDT PRES-15 SW) and connect a light to it.

With the RV-12 it would probably take a factory authorized mod to do it but it would be a good back up pressure indication. If there is a pressure activated Hobbs meter in the system, the switch is already installed.

RGaines · #9 11-05-2009, 08:22 PM

After a long day and the help for many friends we were able to isolate the problem to the sending unit. Hooked up a mechanical guage and it worked fine. Flew it home and took the sender off. Now the problem is going to be getting a new one. The price is $400 and it lasted almost 12 hours. We will see how happy the regional rotax place is about that. Pretty price little part to fail like that.

frankh · #10 11-05-2009, 10:17 PM

and I don't suppose you can pick one up from Dynon and remote mount it on your firewall?

Frank