I already posted in this category about the incident involving a DA42 that experienced a double engine failure after take-off while retracting the landing gear. To be brief, let’s say that the battery was dead, both engines were started using ground power, and the alternator did not sustained the load required by the landing gear retraction, so the FADECs were reset.

Diamond recently published a DA42 batteries service bulletin which introduce a new battery. This new ECU Backup Battery role is to provide FADECs with sufficient power when the electrical load on the alternator is high.

It is interesting to note that this service bulletin mentions twice the fact that the way the accidented plane was started (both engines started with ground power) was not allowed by the AFM:

”On one occasion after starting the engines using ground power due to fully depleted main battery without following the procedures published in the AFM the airplane experienced a dual engine failure and total loss of electrical power.”

Diamond also seems to blame Thielert for this problem, but they issued this service bulletin themselves. You will also see that this service bulletin is optional, not mandatory. Once again, I’m not trying to make a sentence against anyone, the officicial investigation will establish the facts. Nevertheless, such a battery will is certainly an improvement for the DA42.