Vmca is the min dynamic "recover and maintain S&L constant speed" speed for sudden complete failure with gear up and everything else in t/off position - there's no requirement to even demo this in the UK.
All control demos are steady state:
- start at Vyse, gradually throttle back an engine, slow down until a control reaches a limit or Vs+5 reached. Recover by retarding live and lowering the nose before throttling-up both
- as above but at zero thrust
- as above with gear and flap
- as above but at 3-5 deg of bank to live
The only dynamic demos are done well above Vmca: initial failure demo, EFATO, Vtoss.
IMHO fooling around with dynamic failures near to Vmca is asking for trouble and accomplishing nothing -especially if the aircraft is allowed to stall, which must have happened in the situation cited by Centaurus.
BTW, I spend lots of time teaching spinning and aeros in a variety of aircraft but nothing with lumps of mass (ie engines) on the wings; have we anyone here with experience of different spin recoveries for straight winged aircraft with/without wing-mounted stores (or tip tanks)? Most SE aircraft have A<B, it would be interesting to know how spin recoveries change with aircraft when A>B - the info may be useful for recovering a twin.
HFD