Fluctuating oil pressure on a G1000.......

[ScubaMan]

Good evening......

 

 

I have started having irregular oil pressure readings on my G1000. Oil pressure fluctuates from in the red at about 8 psi up to over 60 psi. My mechanic has checked the oil pressure with a mechanical gauge and has determined the oil pressure is spot on. He has worked over the wiring and I still have the same problem. He even contacted Mooney and they do NOT feel it’s a transducer problem or G1000 issue. Has anyone experienced this problem?

 

Thanks in advance for the help

 

Mike Johnson

Mooney Ovation N871TX

[jsclafani]

I experienced a similar problem in a Columbia 400 with an Avidyene MFD that drove me nuts. Everything tested ok but It turned out there was an intermittent short caused by a very small nick in the insulation in the transducer wiring going to the Avidyne MFD and analog gauge and the circuit shorted intermittently from engine vibration. 

[Nathan Peterson]

Mike,  how cold outside was it when she starts to fluctuate?… or does it happen anytime?  

[N601RX]

Transducers generally have a power and ground wire that supplies the power. There is also a 3rd signal out wire that is usually 1-5 volts and that voltage is representative of the pressure it is measuring, 1 volt would be zero psi and 5 volts would be whatever the upper limit of the transducer is perhaps 200 psi? Some have a 4th wire that is the signal common to reduce noise while others just use the power ground for the signal ground.With a meter and wiring diagram it should be easy to see where the oscillations are coming from.

[ScubaMan]

Mike,  how cold outside was it when she starts to fluctuate?… or does it happen anytime?

It's happened on the ground during run up and rock solid for an hour on other flights.

[Nathan Peterson]

Mike, I know you said in was not your transducer.  I had the same problem with the Manifold Pressure…. both transducer's are located in the same area for me.  Disconnected both of them and cleaned them and used dielectric and worked them back and forth… so as to make sure there was a good connection… no problems since. 

[philiplane]

It's almost always the transducer  connector causing this fault. Remove the connector, check for distorted pins & sockets, correct as needed, then apply Stabliant 22 to the contacts and re-install. Very common problem on anything with this style transducer. Cirrus, Mooney, and Beech use it. 

[ScubaMan]

Thanks so much for the advice.... I'll see if I can get my mechanic looking in the right direction......

 

Thanks again

Mike

[Jeff_S]

Hey all,

I'm stirring this topic up because I recently started having similar problems with my MP readouts. I was climbing to 7000' yesterday en-route home to Atlanta and was tickled to see 32" MP.  I didn't realize my Ovation had evolved into an Acclaim all on its own!  <smile>  Then after a few minutes the MP started coming down, which gave my heart a bit of a flutter until it stablized at a reasonable 24.5" and from that point on the readings seemed normal. I went out to the plane this morning and did a power-off test, and the MP started out about right at 28.5" and then climbed to 30.9" before stopping. I didn't try a powered on test.

So from what I read above, first step is to check and clean the contacts. My question is, is this something that my normal A/P can do or does it require someone who knows G1000-specific stuff?  Any thougts are appreciated.

Jeff

[philiplane]

Use Stabilant 22 on the contacts at least annually and your problems will likely disappear.

 

[Jeff_S]

Yes, it was nothing more than the connector that needed some tightening up and cleaning out.  Glad to know there is at least something that's an easy fix on an airplane!