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Oil Pressure, Voltage, Ammeter, Fuel Pressure Readings on the RV-12 D-180

MartySantic

Well Known Member
Thought I would start a new thread and see if those flying have experienced the same. Maybe what I will describe is common and Van's Engineering can do a bit of investigating and potentially suggest a solution. Please add your comments and observations.

I and many others are seeing a sporadic, erratic, unsteady, jumping, an oscillatory or an oscillating oil pressure indication on the RV-12 D-180. I am trying to use all of the verbs I can think of so all can find this thread in the future.

I see the same on the voltage indication on the D-180 and the ammeter indication on the D-180 and at times on fuel pressure.

Have any of you folks that are flying experienced the same symptoms? If not flying, have you seen any info that can suggest a solution? If so, please chime in!

Looking for a solution that can benefit all of us.
 
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I started looking into the erratic oil pressure readings and called Dynon where it was suggested I run a ground wire from the battery to the closest point near the OP sending unit. There was no appreciable change that I noticed. I was suppose to report back to Dynon, but got sidetract by something or other and never did.

Maybe the Dynon dude will see this and report. I sent him a PM.
 
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Usually erratic readings are linked to a grounding problem.... Especially if you seeing it on different gauges at the same time....
 
ERRATIC!

:eek: Yep, All of the above Marty. I spoke to Jeremy at CPS today. He stated that he has heard the same report from others and thinks it is the DYNON and not necessarly the sensors. He says the DYNON is SO sensitive that it regesters everything.I e-mailed Dynon support today about the problem and I am awaiting their reply.I'll let you know if I get an answer.
Paul Shepard 120007
7.1 on the tach......
 
I agree, sounds like a bad ground.

TODR

I would also tend to agree that there is some type of grounding issue. Unfortunately, none of us have a detailed schematic diagram of the RV-12 switch panel. All of the sensors are connected to the switch panel, the signals are processed and then sent on to the D-180.

If Van's would make the detailed schematic diagram available, I am sure we could diagnose the issue and recommend a solution.

Troubleshooting without it is virtually impossible.
 
So as we understand things so far, there are a few different things at play here. The generator on some of the Rotax engines are really noisy, and because of that, you see fluctuations in the ammeter. Because of the inherent design of the D10/D100 series, we haven't been able to fully counter that in software thus far. We'll take a fresh look and see if there's anything else we can do.

Oil pressure is different though. Again, the fluctuations are real, and we don't have an easy way to filter in software without introducing unacceptable delays. However, there are known solutions to this. Flight Design, for example, relocates the oil pressure sensor from the engine to the firewall, with a restrictor fitting on the engine. This helps keep the sensors around longer (they're prone to failure, both the old and new styles), and also damps the fluctuations. Lockwood sells kit for this purpose, but note that making changes to an ASTM'd engine may not be OK without Vans/Rotaxs' involvement, so make sure you work with them. They may or may not be willing to look at a physical change to the installation. I believe we very recently communicated this option to Vans, so touch base with them to see what their thinking is.

We don't hear too much about fuel pressure. Are a bunch of you seeing those fluctuations? What is the amount of fluctuation?
 
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We'll take a fresh look and see if there's anything else we can do.

Thanks!

Could some kind of electrical "dampener" be put in line on the OP sensor to test to see if the "noisey" generator can be overcome?

One of us could try the relocation thing for the OP and see if that works.
 
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Noisy Alternator

If I have this problem I will simply install coaxial capacitors in the output leads to 'zap' the noise...cheap/effective.
 
On the fuel pressure fluctuation - is the sensor mounted directly on the engine, by chance? That would definitely cause issues in both the readings and reliability of the pressure. Per our manual, the sensor should never be mounted directly on the engine.
 
On the fuel pressure fluctuation - is the sensor mounted directly on the engine, by chance? That would definitely cause issues in both the readings and reliability of the pressure. Per our manual, the sensor should never be mounted directly on the engine.

The fuel pressure sensor is mounted on the firewall and not on the engine.
 
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Well, I changed out the oil pressure retaining cap, spring, and the new "cone" (replaces the steel ball) and I happy to report the oil pressure readings are now rock solid.

This is the Rotax SB that is required for 2000 hr TBO. The "cone" is not, but I can highly recommend it if you have OP fluctuations.
 
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Bullet ball

I had the same experience as Larry. CPS said it was the Dynon being too sensitive. I tried grounding and nothing changed. CPS was really wrong. At the second failure of the expensive oil pressure sensory I talked to Lockwood Aviation. They have a remote mounting kit and suggested putting in the "bullet ball" in the oil pressure regulator. They said that fixed it everytime they did it. The oil pressure is now rock solid. I don't have to guess what the oil pressure is. Also the oil pressure sender (DVO) now costs $35 instead of hundreds. It could not possibly be worse than the honeywell one. You do have to run the oil pressure sending wire directly to the Dynon and not through the switch panel. The "bullet ball" is a Rotax part so it is an approved item.

Rich
 
OIl Pressure

Lockwood installed the bullet fix on our N397JC for the oil pressure problem . They did this even though our oil pressure was not fluctuating! Now it does fluctuate!! Have not had a chance to get back to them yet.
Jim Corley
 
My experience

I installed the 3 new parts, and my readings are much better now. Not 'stable', but much better. It wonders up and down some, but not as far a range, and certainly much better.

John Bender
 
no change

I replaced the ball with the bullet part on the oil pressure regulator. Spent almost $50 and no change noted. Will try a grounding wire next. This is a known problem with no help from Rotax or Van's. Very frustrating. I wish I would have gone with the Honda engine from Viking, much better support than Rotax.
Jake
 
Jake, These are my observations on the oil pressure fluctuations you are seeing. First read my thread on how to fix this problem at this link.

http://www.vansairforce.com/community/showthread.php?t=64145&page=4

Because of the vibration on the front of the engine where the electronic sensor is located this is what's causing the pressure fluctuation. If you move the sensor back to the fire wall as shown in on my post then your problem will go away. This will also increase the working life span of the sensor. The rotax 912 is installed in many different type of aircraft from rv12s to ultra lites to sea planes to flying cars to twins, etc. Since the oil pressure comes with the engine it's easier for Rotax to just attach it to the engine even though it's not the best place for it. Whats nice is we as E-LSA builders can modify our airplanes when we discover these things. So buy the kit from Lockwood that is in my post and move the sensor back to the firewall and your problem will be fixed.;)
 
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Questions for John

Hi John,

Your mailbox is full so I'm asking these here.

HI John,

I'm planning to move the sensor to the firewall at the first Annual this fall. I think I have the answers already to a couple of questions but want to make sure. If I keep the Honeywell sensor and move that to the firewall it looks like you just bundled up the extra wire?

And it also looks like you somehow used a double Adel clamp to mount the sensor on top of the fuel pressure sensor?

Final question-- where does the restrictor go-- at the engine end of the line or at the sensor end-- may see that when I look at the parts.

If possible, please reply to [email protected]-- I can't remember to check messages on VAF

THANKS

Wayne Moyer
120241/143WM 55 hours
 
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