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Erratic D-180

J

JohnF

Well Known Member
I got a NO OIL PRESSURE alarm on my first flight after repairing the plane after its takeoff stall. I landed immediatelyl

The alarm was false. The Dynon D-180 acted differently if turned off then on. Indications vary and with no fuel pump on the fuel pressure shows over 85psi, for example. Turning on the GPS makes makes oil temperature vary from 1 to 40-degrees F, sometime jumping to oveer 100-degrees F.

Oil temp if steady shows 13 or 14-degrees F, temp in hangar was 60-degrees.

Turning on autopilot makes the MAP jump to 99.8-inches, then it drops to zero, sometime steady, sometime not.

Pulling fuse for EFIS makes oil temperature vary from 7-degrees F to 35-degrees and it keeps jumping between these numbers.

Ground from power panel to airframe = zero ohms.

Battery ground to airframe solid, zero ohms.

All connections and their pins fully engaged and tight.

Dynon upgraded my software to version 5.4 which I had not yet done, and naturally destroyed all my settings. Now the Dynon cannot detect the OAT or the magnetometer either.

God ! I wish I had simple, reliable, trouble free, stream gauges.

I asked Van's for help: Dynon more or less said the rest is up to Van's. We'll see what happens.

JohnF
 
Depending on how hard you hit the electronics could be fried. They don't make them like they used to. I have a Blackberry that has been dropped, thrown, rained on, left in the sun etc. and it works fine. My Droid I dropped on the table from 1.5 ft and it was dead as a doornail. Obviously phones, but all it takes is something slightly out of place to make these devices go haywire.

One of the students at our school collapsed the nose gear on our Remos, low speed hit and the Dynon was dead. Not sure what the resolution was but the unit was replaced outright by the insurance. From what I heard it looked fine along with all of its connections.
 
yes, D-180 sent to Dynon; they say its OK and can't duplicate what I see.
They upgraded it to 5.4 which wiped out everything and the OAT/mag and the trim icon.

JohnF
 
Erratic D180

I am now convinced that the D-180 is OK as Dynon said it was. The control panel is likely suspect...before stall accident I could not get the "value" digit to change while trying to calibrate the AST, and it was suggested by a forum member that I 'swap' the return voltage line from the trim pot to another pin on the input to the D180 to "bypass" the control board...I did, and that worked fine. So it seems I had an irregulatity in control panel from the 'gitgo" and now have been offered another control panel to swap out to see if that clears the problem. My feeling is that it will, because this morning I found that the autopilot won't work either...if turned on, the lights on the AP74 come on for a second and go out. Calibration attempts halt mid-way and result in a "unsuccessful" reading...that had not been the case earlier.

All grounds, plugs, pins, were checked, ohm-metered, and nothing abnormal found. I loosened all screws on the panel, pushed, pulled, shook, tapped, etc, re-tightened the control panel; no help, no changes noted while doing these things.

My thinking now is that I was supplied a defective panel at the outset. We'll see how the loaner will work.

thanks for your input; I welcome anymore ideas/suggestions/hints/etc.

JohnF
 
JohnF said:
All grounds, plugs, pins, were checked, ohm-metered, and nothing abnormal found. I loosened all screws on the panel, pushed, pulled, shook, tapped, etc, re-tightened the control panel; no help, no changes noted while doing these things.

My thinking now is that I was supplied a defective panel at the outset. We'll see how the loaner will work.

thanks for your input; I welcome anymore ideas/suggestions/hints/etc.

JohnF
Click to expand...

John,
Do you have the specified ground wire attached to the back side of the switch panel using one of the screws on the back cover plate? If you have the ground wire, have you verified it is indeed a good connection to airframe ground?

I am doubtful that a different switch panel is going solve the prblems you are having, but I have been wrong before. I guess we will see.
 
Yes, that ground wire is in and checked; I also added a separate ground wire from the back of the control panel to the aircraft frame. Everything I could think of has been grounded to everything else without effect.

JohnF
 
John, as you might have seen on the blog I have been having Dynon problems for about two months now. I still don't know what the cause, or causes were, but after going to 5.4 my autopilot did exactly the same thing you described, (on for 2 sec. and then off) along with other issues and this week when I re-uploaded 5.4 to seek a solution the Dynon crashed and indicated "internal error- service required. We tried uploading again, but a window came up on the computer saying the Dynon thought it was a D10A. Dynon is sending back my first return 180 as they feel it is ok. I am awaiting it's arrival to try it out. Hopefully they are right. Good luck to you.
Dick Seiders 120093
 
The D180 was upgraded to version 5.4 by Dynon and of course that wiped out everything. Dynon said they should have recorded my settings and put them back in after updating, which they did not. I am going await the loaner control panel and see if that does the trick; if not, then I'll lug a laptop to the hangar and reload 5.4 myself.

I must say that the erratic and changing symptoms I see sure look like some sort of missing or poor ground, but I believe I have eliminated that possibility. Tomorrow I am running a ground from the battery negative terminal directly to the case of the control panel...its the only thing I have not done yet.

JohnF
 
Erratic Dynon

Recap of problem: All normal on ground after about one hour engine time doing various things. Flew and while in the air got alarm of no oil pressure, and other alarms. Immediate landing. With engine OFF Dynon shows MAP 52.7-inches, and fuel pressure (with or without pump on) at 86.1-psi, and trim icon trim tab white arrows jumping up and down.

Dynon checked the D180; said it was OK.
Reinstalled it; no change. Dynon REPLACED D180 with a new unit.
Installed it this morning; No change in MAP or fuel pressure errors.
Now trim "Value" number changed up to 900 and wildly jumped around with nothing being done to trim switch. Next attempt at setting trim, value won't change, but voltage from the Allen servo into the D180 does change. Can't change position of 'green line' on trim icon. Grounds from Allen servo to D180 are OK.

Plane's battery negative terminal to D180 ground reads 3.6mv (5mv is max Dynon suggests in checking unit's ground connection.)

5-volt reference is normal. Measured 5-volts at fuel pressure sensor.

I really don't know what else to do. I tried by-passing the Allen pot's voltage internal airplane wires by running a line from the trim servo pot "around" the airplane's wiring and putting it directly into the D180. Didn't change anything.

I doubt both the MAP and the fuel pressure gauge sensors would simultaneously fail in flight. But that's a different problem than the trim icon problem, yet they all happened at the same time IN FLIGHT.

Battery terminals are secure and input voltage to D180 is normal. Battery and alternator levels are ok, 13.7-volts with engine running from Rotax, and 12.2-volts or more from battery alone on the grouned.

I re-loaded Version 5.4 and Van's locked files and that went OK.

Dynon has been very cooperative and went that 'extra mile' to help me, but their unit, while seeming to be at fault, really can't be after two replacements.

Because this problem did not exist when I took off, the notion that there is a wiring error seems remote, because wires would have had to jump up and move while in flight. Loose pin connections have been pretty well eliminated by checking each wire/pin on all plugs.

I will discuss this with Van's this afternoon; they sent me a loaner control panel that didn't change anything, so I think that is eliminated as a possible source of my problems.

It would be natural to suspect I don't know what I am doing, but if you saw my resume you'd think differently.

I would still welcome CONSTRUCTIVE ideas/views

JohnF
 
John,

How about making up a simple test harness and connect each of these items "On the Bench" to help put to rest where the root cause of the problem is. If you can connect each item on the bench and it works, you know where to focus your energy. If not, you have more firm data for Dynon.

I had my entire system powered up and working on the bench before ever installing it in my plane. This allowed me to understand it all before taking the plunge.

One suggestion....There is no reason to keep reinstalling 5.4 as long as you are sure the load was fully installed and completed without any errors or such.
 
Last edited:
Hi John,

We had a similar problem on the first flight of or latest RV-12 and it was the oil pressure sender wire bundle about 4 inches behind the oil pressure sender, which had sagged down onto the exhaust manifold and it was well burned on the bottom of the wire which caused the 5 V. system to ground intermittently. You may want to look at this just to be sure it is not the issue cause.

Good luck.

Best regards,
Vern
 
D180 Erratic

Thanks, Vern, I just received an email from Dynon giving me a 'heads up' on this and suggesting I pull the sensor wire and see if that clears things up; I will also check for any damage from exhaust/muffler. thanks..will check later this afternoon.

JohnF
 
Dynon Erratic

I pulled the oil pressure sensor and it did not change anything. Vans had alerted Dynon that some are experiencing other problems when the oil pressure sensor goes bad.

Before I pulled the sensor my Dynon display showed the oil pressure without the engine running as "0", that is, zero. After I put the sensor back on the display now shows a rectangular box with three dashes in it. I ran the engine for a few moments to see if that would change..it did not, and no oil pressure was displayed.

I don't know if my removing/re-installing the sensor cause another problem or not.
 
John, you will need to check out all the wiring and connections and when you are satisfied it's ok go after Dynon Support again. There are several very helpful folks on this blog as you already know. Don't kid yourself that you can't get several bad units. You are probably not getting new units for replacement and repaired units are likely not as reliable. I had to sweat and test my repaired replacement unit for 5-6 weeks before it finally went beserk on a 3rd 5.4 upgrade. Until that happened it was "it must be your airplane that is the problem". Then they gave me my original unit back with some adjustments to make certain all the features were on the unit. It's not a happy experience and it shouldn't be necessary. Dynon should replace defective new 180's with new 180's, but that's not the way they do it and Support tells you that at the outset. Van's needs to take steps to work something out with Dynon and provide a little more customer service than we are getting now. Best of luck in your quest for satisfaction.
Dick Seiders 120093
 
Erratic D180

Yes, Dick, you are correct...I am going to open the leads to the oil pressure sensor to isolate that...seems to be involved with problems like this...unscrewing the sensor itself didn't do anything, and I measure 5Vdc at the MAP and at the fuel pressure sensors which is correct, and also at the Allen servo's pot.

Both Dynon and Scott at Vans have contacted me several times today with ideas and helpful suggestions, but nothing has worked so far.

I am wondering if the oil pressure sensor is bad if the one that California Power Suystems would work.($258.66) ...looks as if it would just screw in. I also note that Rotax recommends AGAINST putting the oil press. sensor on the engine because of vibrations, but suggests putting it on the firewall.

JohnF
 
JohnF said:
I also note that Rotax recommends AGAINST putting the oil press. sensor on the engine because of vibrations, but suggests putting it on the firewall.

JohnF
Click to expand...

John,
Can you direct me to where you found that information?

The reason I am asking is I have never seen that anywhere, and Rotax ships the engines from the factory with the oil pressure sensor already installed on the oil pump housing of the engine.
 
Oil Pressure Mountin Location

Scott, I mis-spoke...it was Dynon, not Rotax that made that recommendation. On page 3-6 of the Dynon D180 installation manual it says,
"Due to vibration issues, never connect the sensor directly to the engine."

JohnF
 
Erratic Dynon

Finally !! Vern gave me the pointer to solve my problems. The oil pressure sender failed. When the wire was clipped that goes into the D180 the MAP went to a normal reading; the fuel pressure went to zero psi, and with the pump on went to 3.6 psi, and the AST trim icon calibrated normally and can be set for proper take off indication and is rock solid.

It would appear from Vern's experience and mine, that the D180 internally affects the MAP, the fuel pressure, and the AST trim icon when it gets incorrect voltage/resistance from the oil pressure sender...I have no way of knowing why, but this seems "normal" D180 response.

Keep that in your mind if you get similiar fault indications.

One other thing: Both Scott at Vans and Dynon (Mike) were extremely helpful and communicative in working with me.

Only wish I had a schematic to work with in trying to resolve this.

JohnF
 
Oil Pressure Sender

Wow John, good work finding that problem! I saw something similar but never made the connection that it was affecting multiple sensor values.

I assume the wire you clipped was the mV sense wire from the really expensive honeywell oil pressure sender that rotax supplies? This wire goes into the control panel and, inside that control panel somewhere there is a dropping resistor in-line before the sense wire goes on to the D-180. The other two wires to the oil pressure sender are the power and ground if I remember correctly.

Due to multiple bad senders in a rotax install I've helped with, they changed out the honeywell sender for a remotely mounted VDO sender. The conversion kit is available online somewhere. The wiring trick is that the VDO is resistive so you connect to the existing ground wire and then run a new wire from the other VDO connection directly to the D-180 (pin 6). See page 3-6 of the D-180 installation manual for details. You can't use the existing sense wire since that runs through the control panel and the added resistor. Besides - running the new wire lets you convert back to the honeywell sender if you want.

Hope this helps,

Neil
 
Good going JohnF

Good going JohnF on solving the electrical problems. I am happy to hear that the fault was not with Dynon or Van's control board or with your wiring. It was just a component failure. Who would have guessed that a bad oil pressure transducer would cause those other symptoms.
I received an email from Mike who said that the bad oil pressure transducer could have damaged a resistor on Van's control board. If there are still problems with a new transducer, then suspect that 200Ω resistor. According to Mike, the voltage on Dynon EMS pin 6 should be between 0.8 and 4vdc. There is a schematic of the oil pressure circuit on page 3-6 of the FlightDEK-D180 Installation Guide.
Joe
 
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