What a ludicrous design. Adding documentation procedures is not a human factors solution, it's a recipe for more accidents. If it's the preferred solution to prohibit starting both engines on ground power, then the design itself should prohibit starting both engines on ground power...
Disagree with you there, human factors always play a role in accidents.
Anytime something out of the usual occurs; refer to the POH.
That's what it's there for, that's why it should be within reach of the pilot in the cockpit, not in the luggage compartment.
It is not that hard to follow instructions, section 4B7 DOES read " start one engine only,
here is the copy & paste of the online manual
http://www.diamond-air.at/fileadmin/...4-complete.pdf
' 10. Circuit breakers . . . . . . . . . . . . . . . . . . . . . . . check all in / as required
' 11. Idle RPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . check, 900 ±20 RPM
' 12. External Power . . . . . . . . . . . . . . . . . . . . . . . disconnect
' 13. Opposite engine . . . . . . . . . . . . . . . . . . . . . . Start with normal procedure
' 14.Warm up . . . . . . . . . . . . . . . . . . . . . . . . . . . . IDLE for 2 minutes /
thereafter 1400 RPM
I agree, items 12 and 13 are not highlighted, underlined, printed in italics or otherwise made to attract attention, but still that's what it reads.
On the DA-42 the engines continue to run if you shut off the master switch on the ground.
According to the above mentioned article the ECU's are sensitive to under voltage situations on the electrical bus.
With a battery that is insufficiently charged an under voltage can oocur upon cycling the gear on any other high draw item.