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Oil pressure went to zero, fuel pressure maxed out

Top Cat

Well Known Member
Today cruising at 5500ft oil pressure suddenly started fluctuating on the low side before going to zero with red X. Along with continuous audible warning “Oil Pressure”.
Very shortly after this my fuel flow went to the upper green limit then into caution along with “Fuel Flow” audible warning.

The engine itself performed normally, no vibration, ran smoothly, no obvious oil leaks. Nothing else abnormal.

On descent to the field at above idle the oil pressure indication returned to normal as did fuel pressure. Landing and taxi uneventful and post flight inspection showed no oil loss or anything else abnormal.

Ran it by my Rotax trained and qualified mechanic and his suggestion was to contact Dynon Tech Support which I will do tomorrow as it sounded to him like it was a Dynon issue.

Thought I’d post the experience here to ask for suggestions and/or comments.
Thanks in advance e.
 
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A big red X usually means you have an electrical circuit problem. If you did in fact lose OP then the reading would likely go to @ 0 psi (+ 2-3 PSI) without a red X. Check all of your OP and FP wiring. Could be a sender but more likely a poor wiring connection.
 
Thanks for the info.

Coincidentally I’d just uploaded the latest Dynon software update.

I did wonder about a poor connection but then why would readings be normal at lower power and why does fuel flow increase whilst oil pressure goes down with the same increase in power? How could they be related?

I see by your address that you’re near Santa Rosa? I hope all is well with you and your family with all the tragic fires.
 
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Thanks Top Cat for the kind thought -- we are fine but a number of our RV family here in SR have lost theirs homes, cars, household contents, etc. The fires have been horrific.

Electrons are funny things -- all sorts of strange instrument indications can be seen if the wiring is not 100% up to snuff. In my experience, the RV-12's FP can be erratic for "yet-to-be-fully-understood" reasons -- never seems to interfere with the engine's operation however.
 
Howard--the fuel pressure indicated high? Does sound like a instrumentation issue to me. I wonder if yo would mind sharing your 'normal' pressure indications with us.
Tom
 
Normally oil pressure is around 60 psi and fuel flow about 5.2.

When the oil pressure started fluctuating it dropped to almost zero went up and down until resting on zero flowed by the red X and continuous audible “oil pressure” warning.

The fuel flow to top of green then to the upper caution range followed by “fuel flow” warning.

Reducing throttle brought everything back to normal and that’s the part I don’t get, especially if it’s a bad connection.

Appreciate the help!
 
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Very shortly after this my fuel pressure went to the upper green limit then into caution along with ?Fuel Pressure? audible warning.

The fuel flow to top of green then to the upper caution range followed by ?fuel flow? warning.

Reducing throttle brought everything back to normal and that?s the part I don?t get, especially if it?s a bad connection.

Was it high fuel pressure, or fuel flow?

An intermittent connection usually means something is influencing the connection to make and break. That influence often times is vibration. Vibration changes with engine RPM.

Because you have more than one indication changing at the same time, something that is common to both should be looked at (system grounds).
 
Steve,
My average fuel pressure with engine off and electric pump on is 2.6 psi.
At cruise with both pumps on, the average pressure is 4.3
Keep in mind that the senders are notorious inaccurate. The actual value displayed is meaningless without being verified with a calibrated gauge. It is up to the pilot to learn what is normal in her plane, then take notice if the pressure deviates from normal.
 
Scott,

Sorry yes I meant fuel FLOW went high to the max limit. Ill correct my post.
Now I can't recall if the audible was fuel flow...either way there was a warning audible concurrent with the incessant" oil pressure" warning.
 
I had very much the same condition, I.e. various parameters going high and low in somewhat random fashion. Talked to Dynon at some length. They said it is a strange failure of a pressure transducer. They thought it was the oil px....it turned out to be fuel px transducer.
Good luck
 
UPDATE

Reply from Dynon Tech Support indicated that oil pressure sensor was intermittently shorting the EMS?s 12v supply to ground. They advised me to do a short flight with oil pressure sensor disconnected.
This resulted in all indications normal apart from the obvious lack of oil pressure.

I reconnected the sensor to see if perhaps the connection would be better and did a short flight. Oil pressure fluctauted from start up ghrough taxi and run up all other indications were normal. Briefly the oil pressure returned to normal until take off roll and inflight. Fuel flow was normal.

I downloaded another diagnostic and sent it to Dynon Tech for evaluation.
My main question now is the oil pressure sensor in need of replacement or is there a short from the oil pressure sensor alone?

On a side note, my airplane is an SLSA RV-12 and I?ve seen that there is an option to install a remote oil pressure sensor? Is this an option for an SLSA having been approved by Vans or do I have to simply replace the oil pressure sensor in original location (if this turns out to be the reccomendation)?
 
oil px tranducer

Sounds like you've isolated the problem to the oil transducer. Based on my experience, I also think that's the problem. I would replace and mount at the bulkhead. Don't forget to bleed the line to remove the air bubbles.
Good Luck
MikeB
 
UPDATE

Reply from Dynon Tech Support indicated that oil pressure sensor was intermittently shorting the EMS’s 12v supply to ground. They advised me to do a short flight with oil pressure sensor disconnected.
This resulted in all indications normal apart from the obvious lack of oil pressure.

I reconnected the sensor to see if perhaps the connection would be better and did a short flight. Oil pressure fluctauted from start up ghrough taxi and run up all other indications were normal. Briefly the oil pressure returned to normal until take off roll and inflight. Fuel flow was normal.

I downloaded another diagnostic and sent it to Dynon Tech for evaluation.
My main question now is the oil pressure sensor in need of replacement or is there a short from the oil pressure sensor alone?

On a side note, my airplane is an SLSA RV-12 and I’ve seen that there is an option to install a remote oil pressure sensor? Is this an option for an SLSA having been approved by Vans or do I have to simply replace the oil pressure sensor in original location (if this turns out to be the reccomendation)?

The kit has not been evaluated by Vans for approval on SLSA Aircraft.

It is flying on a lot of ELSA rv-12 aircraft as well as a myriad of other Rotax installations.

In addition we have been able to adapt around the rotax service bulletin that has Rotax owners drill and re tap their engine for new metric style transfucers. If you would like to install the kit, I would recommend calling Vans and letting them know and see what they say.

The remote oil pressure relocation seems to greatly help with erratic indications that are introduced by vibration associated with direct mounting to the engine.

Here is a link to the page showing our remote install kit.

http://aircraftspecialty.com/rv-12.html

If you have any questions, please feel free to reach out to us.

Steve
 
UPDATE

Dynon reviewed my last diagnostic file and determined the oil pressure sensor is the culprit. Intermittently grounding the EMS 12v wire.

I’ll call Vans but I’m pretty sure because I have an SLSA I’ll have to just replace with new sensor in same spot.
 
UPDATE Part Deux

My Rotax. Echanic looked at my plane today and had a new oil pressure sensor which would have required more rewriting to install. He found that they did stock the one on the engine (Keller?) and was about to order one ($250) when he spent a few minutes cleaning the connection and reconnecting. We think the clip may have been slipping, enough to allow the connection to be loose enough to send erroneous readings to EMS.

I did a test flight and oil pressure and fuel flow were normal, as it was on the 30 minute flight home. It would be good if Vans could approve relocating the oil pressure sensor to the firewall for a SLSA.

On a side note the SkyView screen went blank and rebooted on taxi out first flight of day, and did same on short final on last flight home.
 
Lockwood part GAOPSNDHK ($130) is a direct replacement for the Honeywell unit. No requiring for 5V required. I tried reterminating my Honeywell and thought the fluctuation was Fixed, after a couple of flights the issue returned. This Lockwood part solved the problem, and it has a plug connection for easier replacement if required.
 
Thanks for that. We did have one part from Lockwood that was about that price.
My mechanic guy knows the folks at Lockwood well.
I think the Kellar was a one for one replacement and the other required some desiring.
So far we haven?t replaced unit so fingers crossed.
 
UPDATE Part Deux

My Rotax. Echanic looked at my plane today and had a new oil pressure sensor which would have required more rewriting to install. He found that they did stock the one on the engine (Keller?) and was about to order one ($250) when he spent a few minutes cleaning the connection and reconnecting. We think the clip may have been slipping, enough to allow the connection to be loose enough to send erroneous readings to EMS.

I did a test flight and oil pressure and fuel flow were normal, as it was on the 30 minute flight home. It would be good if Vans could approve relocating the oil pressure sensor to the firewall for a SLSA.

On a side note the SkyView screen went blank and rebooted on taxi out first flight of day, and did same on short final on last flight home.

If enough people call vans and ask them to approve the sender relocation, maybe they will come up with a relocation kit. On firewall forward packages for all of our rotax kits, we always relocate the sender to the firewall as it is a much better place for it and also greatly reduces the issues with vibration induced problems. Also, if you happen to have an older style engine with an npt sender, and need a newer style metric transducer, you don?t have to drill and re tap your engine port per the rotax service bulletin if you remotely mount your sender. Unfortunately, this is not available on SLSA aircraft due to a lack of approval from the manufacturer.
 
Thanks I?ll contact them and ask if they will review it for the SLSA.

They did approve the relocation of the VR earlier this year when I asked and I was the first SLSA!
 
Thanks I?ll contact them and ask if they will review it for the SLSA.

They did approve the relocation of the VR earlier this year when I asked and I was the first SLSA!

Sounds good. We have an installation manual already drawn up so they wouldn?t even need to make a new one. It?s a very straightforward and simple install.

Have a great weekend
Steve
 
UPDATE

Vans replied to me that they don?t have any plans at present to approve and document relocating the oil pressure sensor to the firewall for the SLSA.

They did tell me that if I?m using the newer sensor in post 2013(?) engines then it is such that solid state improvements have increased performance and reliability.
This is likely true as in my case (2014 SLSA) I?m still using the original OP sensor but after checking the connections the EMS readings returned to normal.

Please don?t shoot the messenger I?m just passing info on!

On a side not I flew an hour and a half with no screen rebooting by itself. I wonder if I caused the problem by too frequently adjusting g the k-factor in the air trying to get the fuel flow to read realistically, and. Y impatience caused the reboots.

I have to say a big thank you to Vans engineering for a speedy and thorough response, especially in a holiday week when they?re shorter staffed. Greatly appreciated.
 
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