Myth Busting - Engine Inop Performance

[A Squared]

Yep...100fpm in a light twin on one engine can be very exciting considering the alternatives.

Yes, in a engine out situation in a light twin, 100 fpm *up* could be cause for intense jubilation.

I guess I don't really get what undaunted's beef is. We all agree that using rudder and bank to achieve zero sideslip isn't going to press you down in your seat and flatten your eyeballs in thier sockets with the increase in performance, but we all (including undaunted) agree that there is *some* increase in performance. Undaunted appears to me to be advocating *not* teaching pilots about this small performance edge which might save thier a$$ some day. Why, is beyond me.

Think about it this way; say a pilot wth whatever reason (high, hot, overloaded, or just poor performing light twin) finds himself in a position where he's slowly losing altitude with one engine feathered. Consider two ways the scenario could play out.

1) he bores along, wings level, losing altitude gradually until he crashes into a schoolyard, spreading dismembered little bodies across the playground.


2) He banks slightly into the live engine and gets the slight performance boost he needs to clear the top of the swingset, and slowly gain enough altitude to bring it around and put it back on the pavement.


I am at a loss for understanding why Undaunted seems dead set against teaching pilots that option 2 might exist.

 

[UndauntedFlyer]

All members who have made posts on this subject have made good points and as ASquared says, we all really agree. And I have many times agreed that at least trimming to a half ball is easier on the trim and on my leg if that is the only force behind the rudder. There in lies the greatest PRACTICAL advantage of zero side slip with an engine inoperative, less rudder force.

My general complaint is that in GA zero side slip is an over emphasis to where multi students think that ball out of center is always an objective when an engine is inop, it is not. If it is needed, give it a try, why not? It may be a performance enhancement tool to some small degree that could be important sometimes as an "ace in the hole" that theoretically will do some good. As I have said, this technique does not hurt anything with regards to performance. So what the heck, try it before you hit the trees? I would too, why not try anything at that point?

The only real problem is people who I have referenced before in this thread, who try to identify a dead engine with the ball out of center. This has happened several times in my examining work. The situation is the pilot corrects for the engine failure with all aileron and then has to use the wrong (opposite) rudder. Then the student incorrectly tells me which engine is out because "dead foot dead engine" is wrong here. When I ask why the ball is out of center he tells me that it's not suppose to be in the center. This is a training problem.

Also, as I have mentioned here too, I see students trying to fly a 1-engine ILS's and desperately trying to hold the GS/LOC and the airspeed which is hard enough, but to complicate things he is also trying to keep the ball out of center. Of course, when going down hill at partial power there is no need for this at all.

I also talk to people before I fly with them and almost all tell me that the zero side slip technique will enhance performance 3j00- 500 feet per min. When I fly with them they are surprised when it actually reveals no enhancement what so ever, or so slight an enhancement that it is immeasurable. Yes, maybe I am a victim of placebo effect too.

This all tells me that there is, in general, too much emphasis on this element of engine out multiengine knowledge.

To me this whole thing is mostly an over done concept, almost a myth with SOME TRUTH behind it.


Thank you for all your comments on this thread.

 

[infiniti757]

Does any one have any actual numbers for GA twins and their SE performance?

 

[stupidwork]

there is a faa hand out or ac with a list of se climb perf. i cant refence it now because im at home and the paper is at work... but it dose list a dozen or so GA multi engine aircraft. i think its title is "leave your self an out".
wait found it....http://maxwellaeroclub.com/Always Leave Yourself An Out.pdf

 

[100LL... Again!]

The issue is not so much that banking is unnecessary as much as that the whole issue is trained very rote in most cases I have experienced.

Not enough real correlation is being achieved.

I will agree that once performance issues are no longer a concern, wings-level works just fine. (I.E on the ILS).

 

[UndauntedFlyer]

The issue is not so much that banking is unnecessary as much as that the whole issue is trained very rote in most cases I have experienced.

Not enough real correlation is being achieved.

I will agree that once performance issues are no longer a concern, wings-level works just fine. (I.E on the ILS).

Great post 100LL. We are on the same page here. Correlative levels of learning is the objective, not just rote.

100LL you qualify for and E-CFI designation.

 

[minitour]

Yes, in a engine out situation in a light twin, 100 fpm *up* could be cause for intense jubilation.

Hell, even going from 500fpm *down* to 400fpm *down* can be a "cause for intense jubilation"...

-mini