Not much info ATM except 4 POB perished in this sad accident.
https://aviation-safety.net/wikibase/308589
Unofficially, it happened during OEI training with 4 POB, two persons at rear seats were not supposed to be there but for some reason boarded the plane.
My ATO used to pair us (3pob or 4pob) for MEIR training, the goal was to learn from each other and also to demonstrate OEI performance at MTOW on missed…it does make a hell of a surprise one versus 2pob
However, that was taught with large speed addon: French ATO love something called KVe which makes you fly DA42 never less than 100kts, you are nowhere near VMCA or VS 
According to data I collected last month, it was DA42 TDI with CD-135 engines which means not much redundant power. I had real-life OEI with those engines few years ago with 4 POB in cruise and it was feasible (takeoff was at MTOW but the problem developed 2 hours in the flight and 80 kg of fuel less). However, they were probably practicing OEI on takeoff and with 4 adult POB and probably very close or at MTOW. Very small margin for errors.
With these da42 (135) you are easily at mtow (1700 without the big landing gear). We had 3 in the school and 1 had the 1785 mtow extension but had also deice, and finally was heavier in OEI regime for just a bit more to carry.
Anyway with 2 students and 1 FI we were at mtow with less than full tank (50usg of jet, that’s 150kg).
We had one issue only on 30 flight, when my team mate was pilot, landing OEI with a lot of turbulence in LFMQ, a bit rear centered, and the FI took command because he was a bit nervous in very short final.
I didn’t really understand why he took the command back, but reading again that DA42 is not a stall able plane, actually I think he took the good decision .
However, that was taught with large speed addon
The FAA introduced the concept of Vsse in the 1970’s as a minimum speed for purposes of simulated asymmetric manoeuvres. It can be found in the AFM/POH and is typically around a few knots below Vyse and a healthy safety margin above Vmc, around 15 knots plus.
For purposes of asymmetric competence you are expected to climb out asymmetric at Vyse in a range of around plus 5 minus zero, with correct forward slip technique towards the live engine.
RobertL18C wrote:
typically around a few knots below Vyse and a healthy safety margin above Vmc, around 15 knots plus.
Which for DA42 would be Vyse.
It’s been a while since I have flown a DA42, but if I recall Vmc was around 56 KIAS and Vyse 85 KIAS, and Vsse 80 KIAS, or a healthy 24 knots above Vmc?
Again, in Europe, there seems to be some lack of sensitivity towards Vsse, although am glad @lbra’s reference shows a healthy respect in France. In the USA Vsse is treated with the respect it deserves.
RobertL18C wrote:
It’s been a while since I have flown a DA42, but if I recall Vmc was around 56 KIAS and Vyse 85 KIAS, and Vsse 80 KIAS, or a healthy 24 knots above Vmc?
For DA42 TDI Vyse is 82 KIAS (86 KIAS for CD-155 engines) and Vmca is 68 KIAS. POH just explains Vsse without giving some number.
@Emir many thanks for clarifying. Have since found an old DA42 NG AFM and it shows Vmca at 76 KIAS, and Vyse at 85 KIAS. Vsse only gets a generic description with no airspeed in the limitations. I also found some ATO SOPs which treat Vsse and Vyse as an equivalence. This is quite typical in USA MEP training where blue line Vyse is treated as Vsse.
In 1985, I attended the one-year long experimental flight-test course at the USAF Test Pilot School in California where one of the subjects was control and performance after engine failures and subsequent engine-out flight. Loaded with lots of theory we then conducted OEI testing in a 2- and in a 4-engine airplane to determine engine-out flying qualities, including during the traffic pattern, and the Vmca of the airplane.
After a few fatal engine failure accidents in the nineties in my country (NL), I started wondering why, because during flight-testing we did not crash.
After reviewing many accident investigation reports I noticed that pilots and investigators are not made aware anymore of the real value of Vmca, of the limitations that come with it and of the large increase of Vmca during turns. During the past 50 years or so, adequate knowledge regrettably faded away. In some of the posts above, I also noticed this, but I don’t blame anybody – loss of knowledge just happens.
I am sure that you do not want to get involved in a catastrophic accident after failure of one of the engines. Therefore I would like to recommend you to visit the Downloads page of my website and download one or more of the papers (free). There you’ll also find a link to my video on YouTube.
I used my test pilot school course books (for which also links are provided) and airplane design college books during writing the papers. Many pilots already downloaded these.
I very much regret that this accident happened. Please accept my contribution to improve safety. In case you have questions, please do not hesitate to ask here, or direct to the email address on the contact page on my website.
Together we can make aviation safer.
Harry Horlings (75)
