Perhaps I have some learning to do... I am well aware that Vmca maneuvering close to the ground is very high risk, and the cause of too many accidents, particularly when un planned. However, when carefully planned, at altitude, why the worry?
have to demonstrate Vmc - and if we this at too high an altitude, without being aware of the implications, we risk running out of rudder at the same time as we stall, resulting in a spin.
This caught my eye, and I find myself wondering about it's basis. I have been taught that the safest twin, is one where Vmca and Vs are reached at about the same time.
Any light twin to which this discussion applies, would have demonstrated compliance to the following:
Sec. 23.205
Critical engine inoperative stalls.
(a) A multiengine airplane may not display any undue spinning tendency and must be safely recoverable without applying power to the inoperative engine when stalled. The operating engines may be throttled back during the recovery from stall.
(b) Compliance with paragraph (a) of this section must be shown with--
[(1) Wing flaps: Retracted and set to the position used to show compliance with Sec. 23.67.]
(2) Landing gear: Retracted.
(3) Cowl flaps: Appropriate to level flight critical engine inoperative.
(4) Power: Critical engine inoperative and the remaining engine(s) at 75 percent maximum continuous power or thrust or the power or the thrust at which the use of maximum control travel just holds the wings laterally level in the approach to stall, whichever is lesser.
(5) Propeller: Normal inoperative position for the inoperative engine.
I've done this test a number of times, and always found the subject aircraft very compliant. The odd time, a wing has dropped, but was very recoverable, particularly when the power was reduced on the operating engine.
Does the fact that the rudder is hard over as the stall is approached suggest a spin, should things continue, if the aircraft is otherwise symmetrical because of asymmetric power?
Wouldn't it be a reasonable expectation that the candidate pilot be able to keep things under control by reducing power on the operating engine, and managing the yaw and pitch of the aircraft to prevent either a stall or a spin, while flying at the Vmca limits? The aircraft will give a warning of an impending stall, and if the stall is prevented, a spin cannot occur.
Providing that there is adeqaute space between the aircraft, and the ground, are we
that concerned about directional control at Vmca? In the worst case, we don't always need to fly straight, if allowing a gentle turn allows control to be maintained otherwise? For my experience, when attemping to fly an assymetric twin slower than Vmca (when it
is higher than stall speed) the aircraft does not suddenly flop over on it's back, it just starts a gentle turn. Obsticle clearance aside, a gentle turn is not that big a problem, if it keeps you in control otherwise while you sort the plane out?
I offer the following photos, taken by me while testing a Piper Navajo. Near gross weight, forward C of G, Flaps were at 15 degrees, wheels up, left engine stopped and feathered, right engine 75% power. The aircraft was in stable, straight flight, with an intermittent stall warning, but no impending change in controllability. (it was stable enough that I could take photos while flying!)
I also stalled the aircraft in this configuration right after I took these photos, and it had no tendancy to spin (though I did reduce power right away, and keep it straight with rudder).
I know that Vmca training is percieved as high risk, and many accidents have resulted from poorly executed single engine flying. Is it wise, however, to avoid training into these regimes of flight, when the conditions can be well controlled?