Isnt this type of protection already available in the more “complex” types – for example with Kingairs if the yaw damper is engaged no rudder input is required.
However I would guess these systems are very costly to certify and implement and in a twin would need to operate in all circusmtances including when an engine fails because the response must be a combination of rudder and speed.
In a KingAir autofeather is the most important feature in this regard. If you are feathered then problem solved. In a seneca, you won’t climb feathered or not 
but I guess it results in only a slow descent.
You will be fine in the later senecas ;-)
definitely,
At MTOW, landing configuration, I still climb @ 100 fpm on a single engine (the other in transparency with a bit of windmilling), flying blue line on my Seneca V.
That’s not much, but it climbs anyway…
RobertL18C wrote:
The potential for Vmc to be below Vs resulting in asymmetric yaw close to the stall with a resulting loss of control.
I don’t understand this. Isn’t it good (although unusual) if Vmc is below Vs?
A_A easier to explain with a pen and paper. A lot of crews were lost (dozens, possibly three figures for the fatalities?) during Vmc demonstrations in the 1960’s. Typically the exercise would be conducted above 3,000’ AGL in normally aspirated light twins. Vmc drops as thrust on the live engine reduces with density altitude, while Vs remains constant (at least at GA piston speeds). At some altitude Vmc crosses over and is slower than Vs. This resulted in loss of control, typically a flat spin which was not recoverable for some types. As a consequence the FAA introduced Vsse which is minimum safe single engine speed, and is the speed (typically around 10% above Vmc), where the Vmc demo exercise is restricted to.
Some types have Vmc at or near Vs (Seneca), but have enough rudder authority that they have not suffered from this type of loss of control near Vs. However they have scheduled Vsse and Vtoss speeds with a safety margin above Vmc.
Whether Vmc loss of control probability interval dominates modern engine failure probability over hostile terrain, or vice versa, might be very simplistically at the heart of the single vs twin safety debate.
When I have to demonstrate Vmc for training purposes or biannual, the rudder is normally blocked by instructor so I can’t give “wrong” input at the worst time, and we take it until directional control can’t be maintained, i.e. the horizon is starting to drift ever so slightly. We recover from there.
RobertL18C wrote:
Vmc demonstrations
Ah! I thought you were thinking of “normal” OEI situations. In such a case, surely, the lower the Vmc the better? If you lose control in an OEI climb-out at a few hundred feet, it doesn’t really matter if you turn inverted and dive into the ground (Vmc > Vs) or if you enter a flat spin and crash from there (Vmc < Vs) – but if the Vmc is low the chance of losing control in the first place is less. Actually I would think the survivability would be marginally better in a flat spin.
A_A possibly, a flat spin your vertical speed might be around 30 knots on impact – perhaps one for the crash test dummies. Don’t disagree with your logic.
Robert,
Do I understand this correctly – the issue was that the aircraft was actually stalling during a Vmc demonstration before reaching Vmc? And with the engine-out wing stalling first (less propwash) and next to no opposite rudder authority left entered a spin into the (simulated) dead engine that then was unrecoverable?
