Engine failure at low speed in a light twin

[[Steve]]

Please excuse my ignorance, I'm not a pilot.

As I understand it, loss of an engine in a light twin can be fairly nasty at low speed as there can be insufficient ruder authority to maintain a heading.

I would assume that the speed that this happens would increace with throttle setting. Is this correct?

So would it be logical if this happened to point the nose downward and reduce the throttle enough to maintain a heading, advancing the throttle as airspeed builds?

[askop]

Other factors are w&b and config. Acft with MTOM below 5700 are mainly certified under FAR23. They arn't designed to maintain altitude in landing/takeoff config (gear or gear/flap out).

We had a big discussion on this subject during ground school. It seems that the FAA and the JAA use different factors when they define V(mca)?

[foghorn]

Steve,

Yes, you are correct - below Vmca the only safe way to recover is to go symmetrical by throttling back and descending.

Above Vmca, you control the yaw with the rudder, go to full power and think about 'cleaning up' flap and gear.

Makes low speed low height engine failure situations interesting (i.e. take off and landing)

As they say, speed is life, height is life insurance. Doubly so in twin flying (sorry, bad pun...)

[This message has been edited by foghorn (edited 29 January 2001).]

[compressor stall]

Steve,

Here is a thread which dealt in part with this topic you say. It is relevant as it shows that if you have an engine failure at low speed, then you are most likely not going to fly anyway. It in turn links to several ones beforehand which continue the discussion/can of worms.

http://www.pprune.org/ubb/NonCGI/Forum3/HTML/001111.html

But to give more specific replies to your questions:

1. Yes engine failures at low speed are fairly nasty (massive understatement ;))

2. The speed that this happens will increase (note I am not specifying Vmca here) with a higher throttle setting as there is a greater slipstream over wing behind the live engine, causing lift, then subsequent roll and yaw which the rudder is trying to counteract.

3. Sort of...if you were very unfortunate to find yourself about to roll inverted as you run out of rudder, reduce the power on the live engine. Reducing power removes the differential which is trying to flip the aircraft on its back. This seems contradictary to maintaining height, but you have 2 options: Flip on your back and go into an inverted spin into the ground, or close the power on the live engine and look for a forced landing site. Your call!

For your info in OZ askop, we define Vmca as "the airspeed at which an aircraft is no longer directionally controllable with:

The live engine developing full power
Flaps in takeoff position
Gear extended
Dead engine windmilling
Max all up weight
Aft CoG
5 deg angle of bank toward live engine
*scratches head* I think thats it.

Any "improvement" (ie drag reduction, lighter etc) will decrease the speed at which you may maintain directional control.

Whew....and that was at 0450! PS: I am not a physicist, but make no apologies for not understanding your formulae in the time travel thread ;)

{edited to add the 5 degrees AoB which I omitted:eek :)
------------------
Those who restrain desire do so because theirs is weak enough to be restrained.
William Blake

[This message has been edited by compressor stall (edited 31 January 2001).]

[Code Blue]

US Vmc(Air):

Max power on live engine
Most unfavourable ;)CoG (lateral stability not specified)
Max TOW at sea level
Flaps Take off posn
Gear up
Windmilling prop on dead side
Aircraft airborne and out of ground effect
No more than 5 deg bank into dead engine

14CFR part 23

------------------
-.-- --.- -..-

[Ignition Override]

Many of today's multi-engine procedures were learned the very hard way from mistakes in WW2. Ever heard of "One a day in Tampa Bay", regarding the Martin B-26 Marauder (built in Baltimore, MD)?

The B-26 had to take off and land at very fast speeds, due to the short wings ( high 'wing loading') supporting a heavy plane. So short that pilot soon called it "the Baltimore Whore", that is, "no means of visible support".

The new pilots were not prepared for the high speeds, from what I read in several books, and the mechanics were new to the electric prop governors, which were difficult at first to maintain (the C-46 Commando had the same props).

During takeoff, many planes with new pilots ("cherries") were lost when either an engine failed or a prop's pitch would immediately go flat, creating an instant huge drag on one side. Pilots sometimes survived when the Instructor Pilots were prepared to yank both throttles back to idle and ditch in the bay-maybe they had all discussed this beforehand in the squadron and briefed it during taxi-out. At least they had better directional control. One of our pilots has a father whose plane was the only one to return to England from one of the first two B-26 missions over Holland.

Britain/Ireland and the US: two peoples divided by a common language.

[This message has been edited by Ignition Override (edited 31 January 2001).]