Rough translation: "With only a few kilometers left to go to Säve (ESGP) in Gothenburg the aircrafts two computers where knocked out, simultaneously. The engine was ideling and could not be reved up again"
Now, I still have a steel cable from the plunger to the carb on the aircraft I fly. What do you think the above quote actually mean?
I am just speculating here based on what I've heard from fellow pilots and engineers on the DA-40 TDI and the DR400-135CDI, and based on the problems we've experienced with our own ones.
First cause might be a defective load sensor - the "throttle" in previous-century terms. This is, in effect, an electric potmeter but somehow it doesn't work as reliably as you would expect from something that was already developed in the 19th century. And there's only one in the aircraft, so even though the rest of the system doesn't have a single point of failure, this one does. Ours has been found defective and has been replaced, but it took a long time to diagnose.
Another cause might have been the ECU Auto/swap switch. If no guards are installed and no HSI reset switch installed left of it, this switch is very exposed to feet and knees of pilots getting in and out of the LHS. This is what a mate of mine had in the circuit somewhere in the UK. The ECUs would swap continuously, leading initially to surges of power and eventually to an undocumented failsafe mode where you would get 0% power with the load lever at 0%, but 100% power at any other setting.
The third problem is something we've had in a Robin Ecoflyer, and for which a mandatory SB for the Thielert 1.7 has now been brought out. This is concerning the oil nozzles that spray oil on the bottom of the pistons for cooling. One of them broke off, leading to a partially seized piston and a gradual loss of power. Aircraft landed in a field, no further casualties to persons or aircraft, fortunately.
If, as the report says, the engine was "idling", I assume that the computers were still running. This engine cannot, as far as I know, idle without the computers since the fuel injection is timed by them. However, we're talking journalists here and they also may have meant "windmilling" which I think would happen if both computers would fail.
I haven't flown a DA40 for a while, how long does the battery last if the alternator gives up the ghost?
It depends on whether the aircraft has an IFR or VFR kit. I haven't checked the full POH but my emergency checklist suggest 30 minutes on the essentials bus (one radio) and one hour on the battery bus (attitude gyro and cabin floodlight). As far as I remember, if the aircraft is IFR, it has an ECU backup battery which kicks in automatically and should have juice for 45 minutes of ECU running.
Basically, any alternator caution or other indication that there's something wrong with the electrics is grounds for an immediate landing at the nearest airport, and to conserve as much electricity as you can in the meantime.
Pretty cool pilot, after making the emergency landing on a straight stretch of road, he managed to steer it onto an exit ramp!
Not unheard of. The 777 that landed "short" at Heathrow a few weeks back took the first exit too, proving that you can land a 777 on 400 meters of grass.