I totally agree, Dave, and did not state anything different. Most ECU “failures” have nothing to do with ECUs. They are just doing their jobs of saying that they are sensing something that is not right, or at least that some sensor is saying something is amiss. What I am saying is that if you get an “ECU fail”, the first thing to do is carry out VFAs. And if that fails to restore the situation, then it is time to bring out the checklist. I am also saying that the DA series checklist on that particular point is not very well made.
I think we agree. My approach to the DA42/62 is that an ECU fail caution is an irritant and/or a wake up call rather than a coffee spilling moment. Generally, if there is something serious happening there will be coincident problems with RPM, power, vibration etc. In those circumstances, one largely follows the same technique as you described or would in any AVGAS burner, with the priority being an immediate ‘try this’ followed by a successful feathering.
As an aside, I had an ECU B Fail on the DA62 last week. At the time, the nearest airfield (indeed land) was a little over 250nm away. As a crew, we spent some time discussing the merits of going through the Voter reset procedure! 
Air, fuel and electrics (spark) are vital actions for engine troubleshooting in any piston engine
Except that there is no spark on these engines and instead a whole bunch of electronics and software.
I personally think that the ECUs should be able to report “ECU A/B/Both Sensor Error” distinctly from “ECU Fail”.
If it’s a sensor error, report it as such, not as an ECU failure which it isn’t.
My problem with the Diamond checklist is it doesnt seem to tell you what the error might mean. In contrast see below for the Mustang ENG CTRL SYS message checklist item D5.
Dave_Phillips wrote:
My approach to the DA42/62 is that an ECU fail caution is an irritant and/or a wake up call rather than a coffee spilling moment.
That is what I thought too, but the ECU FAIL may just be a warning of something much worse about to happen.
I first got a ECU FAIL on the right engine. I scanned the engine instruments to see if something was obviously wrong, and I then got the second ECU FAIL on the same engine. The engine kept running normally. I reached for the checklist, opened it to the ENGINE TROUBLESHOOTING page (which happens to be in the Emergency procedures section). Since I had both ECU warnings on, I started down that list when the right engine suddenly partially lost power and I got other things on my mind (disconnecting the A/P and keeping the blue side up), and then the left engine gave me the same treatment. When I advanced the throttle of the right engine that was still generating 30% power, the RPM increased and then dropped without any change to the power indicator.
In my case opening alternate air would have resolved the issue immediately, even before the engine lost power. I beat myself over the head for not doing these VFA but
)So from my experience I would recommend that whenever you get an ECU FAIL warning with a Thielert or an Austro, you carry out at least the first 4 items of the DA42NG “ABNORMAL PROCEDURES” (above) from memory immediately, without thinking (even in the DA40NG since the abnormal procedures do not contain anything useful). Those 4 items cannot do any harm, may resolve the issue or at least prevent the issue from developing further.
For what it’s worth, the DA62 AFM stipulates the following:
This is an after take off check which subsequently applies through all stages of flight. Clearly it is susceptible to engine icing although, to be fair, this particular airframe is awaiting FIKI clearance so the checklist may change.
Dave_Phillips wrote:
This is an after take off check which subsequently applies through all stages of flight. Clearly it is susceptible to engine icing although, to be fair, this particular airframe is awaiting FIKI clearance so the checklist may change.
Same thing for the DA42 (NG). Same thing for the DA40-180.
It may not be in the checklist, but it is in the manual.
…. but not for the original (Thielert) DA42s. Hmmmm.
There is surely no case for alternate air in visible moisture. That’s plain daft.
There is a case for alternate air in freezing IMC and specifically in specific temperature ranges e.g. -15C becoming -5C due to compression (and whatever else) and icing up the air duct components.
If someone wrote that alt air should be used in all IMC regardless of temperature they are IMHO covering up a specific temperature range vulnerability which may have been implicated in accidents.
Peter wrote:
There is surely no case for alternate air in visible moisture. That’s plain daft.There is a case for alternate air in freezing IMC and specifically in specific temperature ranges e.g. -15C becoming -5C due to compression (and whatever else) and icing up the air duct components.
If we assume they didn’t put it in just to give the pilot something to do, then as it is in the checklist prob best to follow it.
We have to use engine anti-ice from +10c and below in visible moisture. At +9 can ice form on the engine inlet? I truly doubt it but I follow the checklist anyway.
