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Oil Pressure Fluctuations

bernsbm

bernsbm

Active Member
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Hi All,
My RV12 has 50 hours TT, and I'm really enjoying the way it flies. Over the past 5 hours or so, I've noticed the oil pressure continuously fluctuates by 1-2 PSI around ~55, with onset after the oil warms up. I've replaced the spade connectors with butt connectors (no change in fluctuations). All other engine indications are normal. The Rotax was purchased in April 2016 and has the standard oil pressure sensor (ROTAX 456-180) mounted on the oil pump.

Here's what the oil pressure looks like:
https://photos.google.com/photo/AF1QipN1aPKt6cnjS58b2pto-hGZ1tXTKeD385CT7I6v

I've reviewed the oil pressure fluctuation video on Rotax-Owner.com and wonder if an engine with 50 hours would have problems with the oil pressure relief valve, or is this more likely a problem with the sender.

Thoughts and suggestions to troubleshoot greatly appreciated
Barry
 
1 or 2 psi fluctuation sounds normal to me. It is even better than normal. There is no problem to troubleshoot.
 
I'm with Joe. 1-2 psi OP variation is excellent for the 912. The apparent accuracy of digital readouts has led many to envision issues where none exist. Fly on and enjoy!
 
Normal

Don't even begin to worry about it. The senders attached directly to the oil pump do begin to fluctuate after a time. They really work best when remote mounted with a restrictor in the line. It reduces the pulses from the oil pump, and the senders last longer.

Vic
 
Gagarin737 said:
It started with small fluctuations, becoming larger and after +/-50 hours my oil pressure sensor failed. I bought the remote oil sensor kit from aircraftspecialty.com and the pressure is stable since then.

ROTAX 912 REMOTE OIL SENDER INSTALL MANUAL REV 2 7-12-2015
Click to expand...

I note you live in Wisconsin. If you plan to fly in the colder months I highly recommend you install not inly the Aircraft Specialty remote sensor, but also their oil thermostat kit. Without the thermostat the warmup to 122 degrees takes an excessively long time, and the oil will not get hot enough to boil off moisure.

http://aircraftspecialty.com/rv-12.html
 
Last edited:
Thanks for your thoughts on my "twitchy" oil pressure readings, comments this is normal, and suggestions to move the sender to the firewall. Have also thought long and hard about the thermostat kit (while shivering/waiting this past winter for the oil to reach the magical 120F).

I'm a compulsive downloader of Skyview Data Logs. On review of early flights, it appears the oil pressure fluctuations have been there since Day 0... Maybe a bit more pronounced recently. Will definitely consider remote mounting my sensor!
 
Barry,
I would suggest that you read a somewhat related thread on the rotax-owner.com discussion forum. Search for "severe jittering oil pressure" in the 912/914 Technical Questions section. You might find it interesting.
Alex
 
SV Density Altitude/OAT Fluctations

Unable to find a post regarding causes of DA/Temp fluctuating indications. Any suggestions?

Oil pressure Fluctuations are not unique to the RV-12. I moved the sensor on a Ran's S-19 to the firewall and they stopped.
 
Last edited:
Doug,
Since DA calculations use temperature, look for a loose connection from the OAT probe to the SV.
Alex
 
Thank you Alex, that is where I will start then.

I didn't build the bird, but looking at the KAI and the probe location I'm heading for the port wing root area and looking for a loose 22 gauge pin??? I should say, with the engine shut down it reads as it should, steady, its just with engine turning that both flicker and reading appear to vacillate...

Thanks again for your response.

alexe said:
Doug,
Since DA calculations use temperature, look for a loose connection from the OAT probe to the SV.
Alex
Click to expand...
 
Doug,

I'm at home and all my documentation is at the hangar. I wont be there until tomorrow afternoon. From my recollection, the OAT wiring harness goes back to the ADAHRS-200 (in the fuselage) and terminates on a nine pin connector. There might be an intermediate connection in between, but I'm not sure at this point.

If anybody has the KAI or schematics handy, please speak up.

Alex
 
No intermediate connection. It goes all the way back to the ADAHRS. The OAT connector is the small one to the left of the d-sub 9 (see picture below).

OAT wiring see page 14

adahrs-201-front.jpg
 
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