Engine issues in both engines of a twin are usually fuel (lack of)... or (IIRC) in the case of the DA42 an alternator failure following a departure with a flat battery.
That trip looks to be around 500NM or about 3.5 hrs flying time.
80% cruise power for 12 gallons/hr for 42 gallons fuel required.
With full main tanks only (50 gallons) they would have had sufficient VFR reserves.
That's a very "interesting" fuel calculation, B2N2.... 8 gallons in the tanks
at the planned destination? I burn ~11 USG/hr and my absolute min would be 20 gallons. 8 is so low that one needs to read the POH to see how much sideslip is allowed before one unmasks the tank outlet
