DA40NG Coolant Leak and ECU A Failure

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gcampbe2
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DA40NG Coolant Leak and ECU A Failure

Post by gcampbe2 »

I've got a tale of woe to share that I though you all might find interesting/useful. I'll be sure to post updates on root cause, and how this gets resolved.

Long story short: I've got a new DA40NG that rolled off the line in July of 2021. Since the first day there has been ongoing small amounts of coolant that I occasionally observe under the engine cowling during pre-flight. I discussed this with my instructor and the company I bought and maintain the plane through initially, and it was not considered a cause for concern.

Fast forward until a week ago, and suddenly I am experiencing COOL LVL warnings prior to the coolant reaching normal operating temperatures, which is perhaps not unexpected since the coolant has likely dropped low enough to trip the sensor prior to heating up. The plan was to get the plane to Toronto (a 2 hour flight) this morning so it could be checked by a mechanic familiar with the Austro engine. I never made it. Although the COOL LVL warning did permanently go out once the coolant came up to temperature, the ECU check failed with an ECU A caution, which will now simply not clear, regardless of running the checklist to clear the ECU failure on the ground and restarting the plane several times. In the timeline below I've got video's linked of the COOL LVL light going on and off, the ECU A failure refusing the clear, as well as coolant actively leaking after the plane was put in the hanger this morning after the aborted flight.

Here's the detailed history:

July 24, 2021. On the second day of my transition training my instructor and I noticed coolant on the floor of the hanger. To my recollection it was not a large amount, and did not raise significant concern at the time; just something we would keep an eye on. This small amount of coolant leakage was something that we continued to observe from time to time during the transition training.

August 16, 2021. The plane is serviced at the London factory. Although I had discussed the coolant leak with the company managing my maintenance, it does appear as a listed item on the maintenance sticker from that servicing. It seems possible the coolant system was never inspected.

August 16 – November 13th, 2021. Every once in a while I would notice a few drops of coolant on the ground during my pre-flight. In my mind this had (incorrectly) become normalized, and I didn’t think too much about it. At no time did I ever observe the COOL LVL warning illuminate.

November 14th, 2021. During my taxi prior to takeoff I noticed the COOL LVL warning temporarily illuminate. This seemed to happen briefly during turns, and immediately extinguished. The warning did not occur during the rest of the flight, despite my doing several stalls, slow flight, and slips in both direction.

November 15th, 2021. During my walk around I noticed a few drops of coolant under the rear cowling again. Upon starting the engine the COOL LVL warning illuminated and this time, for the first time ever, it stayed illuminated. I decided to let the engine warm up a bit and see what happened. After about 5 minutes, as the coolant temperature started to approach the green zone, the coolant warning started to go on and off every few seconds. The frequency of this seemed to diminish the warmer the engine got. I suspect that had I let the engine/coolant come fully up to temperature, the light would have stayed off. Regardless, it did not seem wise to embark on a night flight with the coolant apparently approaching a critical level. You can find a video here (https://mail432com-my.sharepoint.com/:v ... g?e=gilGo0) of the light coming on and off with the coolant at 56 degrees. Note all videos are 1080p, so if they seem of low quality you might need to download them before playing them to get the full quality. Also note that there was an ECU A warning soon after the engine was started, but the normal process of clearing the ECU caution resolved this issue immediately (i.e. place the ECU voter switch to A for five seconds, then back to auto).

November 20th, 2021. The plan was to perform a prolonged run up to allow the coolant to come fully up to temperature, hopefully clearing the COOL LVL warning, and then fly the plane to Buttonville for servicing. During initial run up the COOL LVL light warning illuminated as expected. However, once the coolant level reached about 73 degrees, the COOL LVL warning ceased to occur. At this point I move on to the ECU check. Prior to the ECU check neither the ECU A or B warnings were illuminated (i.e. the ECUs appeared healthy). During the ECU check I immediately observed that the ECU A check did not sound normal. In a normal ECU check the load would increase to just above 50%, then temporarily reduce to about 30%, prior to increasing again to 50%. The engine would normally return to idle and repeat the process (presumably on the other ECU). On this ECU check the initial increase to 50% load occurred as expected by then it simply stayed at 50% load during the time it should have temporarily reduced. The engine then went to idle as normal and the second sequence of 50%-30%-50% sounded completely normal. Upon completion of the ECU test the ECU A caution was illuminated and stayed permanently illuminated from this point on, regardless of attempts to clear it including restarting the engine twice. You can see video of me attempting to clear the ECU A caution here (https://mail432com-my.sharepoint.com/:v ... Q?e=7zGlKK). I cancelled the flight, and put the plane back in the hanger.

November 20th, 2021. About 10 minutes after putting the plane back into the hanger following the aborted flight to Buttonville I noticed a small amount of coolant on the ground. I was able to capture video of coolant slowly dripping out of the engine cowling, which you can watch here (https://mail432com-my.sharepoint.com/:v ... g?e=jYHpw3).

I'll keep you posted as the saga progresses!
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Donkadillapig
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Re: DA40NG Coolant Leak and ECU A Failure

Post by Donkadillapig »

Greg,
you have my commiserations. I too have a recently off the line NG, delivered April '21 and have been plagued with maintenance hassles.
Two MSB's, one AD, a rattling brake caliper and now a replacement fuel transfer pump, not bad for 6 months! ;)
But..... I've learnt a lot and oh what a great airplane when it's working ;)
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Re: DA40NG Coolant Leak and ECU A Failure

Post by Soareyes »

I've purchased four planes new, every one required a shake out period to get dialed in. These are hand-made, one at a time, complicated machines and we push the engines pretty hard. After the first year or so the maintenance experience usually smooths out.

Smooth is a matter of perspective of course. Cars have spoiled us. Normal for an airplane after the first year in my experience is to have an unexpected mechanical problem or AD maybe once every two to three years. Still a PITA but not as bad as the first year.

The first year with my new DA42 saw two new turbos, two new oil pumps, one new current sensor and voltage regulator and a software mystery. Hoping that it is going to be it for a while.

The voltage readings on the other engine are fluctuating a bit though...
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Re: DA40NG Coolant Leak and ECU A Failure

Post by Donkadillapig »

Dan, Thanks for this perspective and experience. Deep down as grown ups I guess this is inherently known... however, inside me, the 11 yr old boy with his eyes forever on shiny objects up in the sky wants to go flying NOW dammit!!! lol ;)
We are indeed lucky kids :)
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Re: DA40NG Coolant Leak and ECU A Failure

Post by krellis »

Yet our DA40-180XLS served us well for over 600 hours (bought new) and had one warranty claim for a bad starter.

I feel for you guys with the Austros - replacing gearboxes, pumps, injectors, ECU faults, coolant leaks. Yeah they run smooth and sip Jet-A, but I really don't see the advantages when you spend so much on repairs and suffer the downtime.

Give me a Lycoming IO-360-M1B anytime (neighbor has 3500+ hours on his)...
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gcampbe2
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Re: DA40NG Coolant Leak and ECU A Failure

Post by gcampbe2 »

I feel for you Steve. It's such a wonderful airplane, but it appears we might be on the bleeding edge of new engine technology. Hopefully once this latest issue is sorted I'll be good to fly for a long time before the next hiccup. In reality I've only had the fuel pump gear replacement and now this coolant issue, which really existed from day one.

As Dan mentions though, I have pondered whether a 180XLS is a more solid choice, if nothing else than because there are local maintenance people who know that engine and could deal with most issues. As I've discovered, this is decidedly not the case for the Austro engine. Right now my plane is grounded in Ottawa, with the nearest mechanic apparently in Toronto. I guess I'll find out how good the after-sales service is!

But boy, would it be hard to give up that look on other pilot's faces when they get into the NG for the first time and you turn the key; that engine just purrs! And the single-level FADEC spoils you really fast...
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Re: DA40NG Coolant Leak and ECU A Failure

Post by Soareyes »

krellis wrote: Mon Nov 22, 2021 11:45 am Yet our DA40-180XLS served us well for over 600 hours (bought new) and had one warranty claim for a bad starter.

Give me a Lycoming IO-360-M1B anytime (neighbor has 3500+ hours on his)...
I agree. My experience of 1,000 hours in a Lycoming DA40 was the same. Just one AOG event, an inexpensive starter that was replaced on the ramp at an out of the way airport by a local wrench turner. Had pretty much the same experience over 700 hours with the Continental in the Cirrus, just a new starter.
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Re: DA40NG Coolant Leak and ECU A Failure

Post by gcampbe2 »

An update on this:

1) The coolant issue was found to be leaks at two locations: The line to the cooler by the exhaust pipe and the line going across the top of the engine. However the mechanic noted that every clamp in the system needed tightening. It seems like perhaps whoever installed the coolant lines at the factory could have used a little more elbow grease!

2) The ECU failure was a prop governor warning. Apparently this can occur when the test button is released prior to the test being completed. I'm pretty sure I didn't release the test button early, but given multiple ground runs have not had the problem recur, I'm happy to just keep an eye out for this issue in the future, and make darn sure I don't ever release the ECU test button early.

So, in the end, very minor issues, and the plane is quickly back in service :)
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Re: DA40NG Coolant Leak and ECU A Failure

Post by Colin »

On the ECU error: When I first had my plane (TDI engines) I got ECU errors in flight that were apparently "CAM SHAFT SENSOR." That's not something it looks for in flight, apparently, so it was a truly spurious error. Then, after a few months, I stopped getting them. As a computer guy, that bothers me a little, but I've never really understood the subtleties of hardware.
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Re: DA40NG Coolant Leak and ECU A Failure

Post by Karl »

Colin wrote: Sun Nov 28, 2021 2:36 pm On the ECU error: When I first had my plane (TDI engines) I got ECU errors in flight that were apparently "CAM SHAFT SENSOR." That's not something it looks for in flight, apparently, so it was a truly spurious error. Then, after a few months, I stopped getting them. As a computer guy, that bothers me a little, but I've never really understood the subtleties of hardware.
Hi Colin, Did you update the engine software during that time?

I was told the cam sensor issue was due to a change of manufacturer and that the tolerances of the new sensor didn't match too well with the software and that it would be adjusted with a new software amendment.
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