Maybe the mains were already full and they just needed to top up the aux tanks.. burn some off of the mains and then switch to drink from the auxiliary part way through the flight
Magnetos FTW!
The 42 NG will feather automatically when the rpm drops below 800(?) if I remember correctly. It’s not a separate function or control.
Sounds like the ECU batteries are an annually-serviced item, so unless it’s less than a year old, it wouldn’t be a factory error.
And you are at the mercy of the service facility on this one. The emergency controller unit switch backup battery is safety wired off and the preflight check is to make sure it’s off and wired so. At least in DA-42NG and DA-40NG.
So these engines have an EEC dual battery system vs a FADEC permanent magnet alternator (PMA) system? I thought Austro used FADEC or am I thinking of something different?
Depends. Maybe the pilot was the one who changed out or worked on the batteries?
From what I’ve heard, this isn’t a very preflightable part of the airplane, so he’d probably have to be looking directly over the mechanic’s shoulder to find it.
I don’t know enough about it…I’ve heard it’s not part of the normal system checks, but I don’t know if it CAN be checked.
While I dont know the particulars on a DA62, battery replacement/servicing does fall under Part 43 prevent mx. However given the avionics and the engines shutdown about the same time, fuses blown on the EEC batteries and the main battery at 70% capacity it appears there is more than one issue at hand. As a reference, 85% capacity is the bottom limit on serviceability for most batteries.
Diesel engines are VERY intolerant of water in the fuel. Among other things it can flash to steam and blow the tips off the injector nozzles, besides for wrecking the high pressure pump and just not being flammable.
Not on the 42 and I reasonably sure on the 62.
Perhaps. I mean it’s the third backup and is annually serviced. If this is due to a servicing error change the procedures. Retrofit to the whole fleet? Maybe not.
Yes, after I posted that I thought more about it. That's the backup power for the essential buss. 30 minutes of AI and minimum radios to get on the ground if both alternators and the battery (ies?) are shot. ECUs have their own backup. I would have thought they'd test as part of the automatic engine run-up. It does switch back and forth between ECUs during that (and as part of the pre-flight checks). It was April when I last flew the DA-42NG.
Or connected in reverse polarity? The report mentions blown inline fuses on the backup power side. How do the back up batteries come on line?
Is it possible to do something like leave the alternator side off on a split master so the ECUs were running off the batteries until they ran down?
Do you have a schematic for this? What's interesting is the avionics and engines failed at the same time. Why the avionics? Given the main battery was junk, maybe it tripped (the pop noise?) the charge system causing loss of main power that dropped the avionics and FADECs? And when the ECU back up batteries "came on line" they smoked the fuses due to "improper" wiring or a failed diode? Will be curious to know if he had to jump start the plane to leave.
Per the AFM there would have been a number of lights lit up and low readings if flying with both ALT out. And if he was, he owns this. What's interesting is those ECU back up batteries also power the alternator field windings in the event of a main battery failure and not just the ECUs and respective fuel pump. My SWAG is the main battery went belly up in flight and tripped the main CB which caused the #1 & #2 alternators to scram and instead of the #1 and #2 ECU batteries coming to the rescue smoked due to "improper wiring" on both systems. You would think at least one engine would have stayed running with 5 separate yet interconnected on board power sources. Ahhh, technology only as strong as the weakest link... or wire.
