Trouble with multi engine OEI approach

[SNOWBANK]

Hi guys, just wondering if someone could give me some advice. I am finishing up my multi commercial instruction and headed for the commercial multi checkride within a month or two. I'm doing pretty well, but just can't really nail the one engine inoperative ILS approach under the hood. I am flying an Aztec, and as soon as one engine is failed, I get all sloppy and can't keep the needles centered down to the runway. I feel like there should be some method or style as to make this nice and smooth, but nothing has been working so far. Also, there is a ton of info through DVDs or printed material on standard single engine flying, and instrument flying, and multiengine flying, but nothing covering the OEI ILS approach under the hood.

I appreciate any help!

 

[poadeleted20]

Trim! Especially rudder trim. If you aren't fmighting an aching leg, it's a lot easier to be precise, especially with a 260 HP engine trying to turn you around. Beyond that, make sure you get stabilized in an appropriate configuration at an appropriate speed before you hit the GS so all you have to do is reduce throttle a few inches to start down.

 

[Henning]

First question, are you trimming the plane in all axis? That is the first key, get the plane to fly itself in your caddywompus ball half out 3°-5° bank into the good engine. Now it is like flying any other approach; until the end when you break out for landing and go visual, immediately start taking out the rudder trim for when you reduce power, or be ready for it when you bring back the other engine to go missed.

 

[bobmrg]

I trust that you have the plane cleaned up prior to interception. Bank angle should only be a couple of degrees with the ball slightly out of the cage. I'm guessing that you are overcontrolling...which goes back to the trim question asked by others.

Bob Gardner

 

[Palmpilot]

This may or may not speak to your problem, but when I did my initial instrument rating, my CFII had me doing so much partial panel work that I got in the habit of relying mainly on the VSI and turn coordinator for attitude control, even when all the instruments were available. When it came time to learn multiengine OEI approaches, I found that I had to pay far more attention to the attitude indicator in order to be successful. (I also had to get in the habit of keeping my course corrections small when flying a localizer.)

 

[SNOWBANK]

This may or may not speak to your problem, but when I did my initial instrument rating, my CFII had me doing so much partial panel work that I got in the habit of relying mainly on the VSI and turn coordinator for attitude control, even when all the instruments were available. When it came time to learn multiengine OEI approaches, I found that I had to pay far more attention to the attitude indicator in order to be successful. (I also had to get in the habit of keeping my course corrections small when flying a localizer.)

That is getting close to the problem. I figured out something today similar to this that helped me out.

And thanks guys for all the responses. I believe my problem is a combination of trim (too much overcontrolling as Bob mentioned), focusing on the wrong instruments, and going through the steps too fast when the engine fails.

Today, I tried an ILS approach with no hood (though still only focusing inside) and no engine failure. After getting set up and on the needles, I simply focused nearly all my attention on the HSI and the ASI. And it worked great, all the way down to minimums. Then I did the same on the next ILS approach, but the instructor threw in the engine failure this time. I then went VERY SLOWLY, focusing again on the HSI and ASI. I took deliberate, slow steps to feather, etc (all the usual steps) and just kept focusing mainly on the HSI with occasional glances at the ASI to make sure I was good on speed. It seemed to work much better, and with a strong crosswind today to boot - I think I was focusing too much on the VSI and altitude indicator before. I will try again next week and see if I can improve further.

One thing mentioned above was Rudder Trim. I had never touched it, and my school doesn't want me touching it during OEI training. I then asked a friend of mine who is a great instructor, and he said with piston twins he never recommends it. I then asked another friend who is a former examiner and he said the same. Soooo I think for now I will stay away from including rudder trim in the equation. I will say, this Aztec doesn't seem to need much rudder to split the ball during OEI approaches. During cruise flight with OEI, it does, but not when coming down under less than full power. This Aztec has a big-ass rudder, maybe it helps.

Thanks again guys, I'll keep you updated.

 

[flyingron]

They don't want you touching it? OEI is the main reason it's there. Most planes can meet the certification requirements for lateral/directional stability without requiring rudder trim until you get to the requirements for single engine operation. Until then it's a convenience.

 

[Henning]

Your MEIs are complete morons and have never had to complete a OEI flight for real. Not having the plane in trim is doing nothing but ****ing yourself, and not being in the habit of using it will do nothing but serve to kill you and your passengers in a real emergency.

 

[MauleSkinner]

Your MEIs are complete morons and have never had to complete a OEI flight for real. Not having the plane in trim is doing nothing but ****ing yourself, and not being in the habit of using it will do nothing but serve to kill you and your passengers in a real emergency.

Yabbut...only REAL MEN with BIG LEG MUSCLES should be allowed to fly the MIGHTY AZTEC!!!

The OP should ask his instructors if they've ever heard of the Law of Primacy, or maybe the Law of Exercise...

Edit...should we guess that the reason the FBO doesn't want you to mess with rudder trim is that somebody didn't reset it, somebody else had trouble flying it, and the FBO had to eat the cost of a maintenance flight to figure out what the problem was, because nobody trained anybody on the proper use of trim?

 

[Francis A]

For the glide slope to work out easy, know the numbers; manifold pressure, attitude and rate of decent, you can get a pretty good idea of what the rate of descent should be for a standard 3º glide slope by multiplying your Ground speed by 5, so if your making the approach at 90 knots (GS) then your target rate of descent will be 450 FPM. whilst practicing make a note of which attitude and power setting is holding you on slope for that speed and then always go for that, making the necessary very small corrections.

If your in level flight prior to glide slope intercept (Engine out) trim for level flight, trim for directional control with just a tad of foot pressure. When the glide slope is around half way down he scale , (this depends on the speed you are at) ( slower aircraft wait until G/S is almost on - faster aircraft such as B737 when G/S come alive) just the fact of putting the gear down and flaps to approach flap for engine out, the increased drag will automatically start your descent and you should not need to reduce the attitude much perhaps just a couple of degrees nose down from what it was in level flight. the power much the same, reduce power a little to stay at the correct speed and then the directional rudder trim should not need to be changed much more than taking out that little foot pressure you had before. The thing is here not to make large changes in speed and power at glide slope intercept otherwise everything starts to go wrong.
As for rudder trim keep it as is until you are either assured of landing or going to make a one engine go around. If you are assured of landing then start to take out the trim, if you are going to make a go around then you already have half the rudder trim you will need for using full power. Never focus on just one instrument, keep the scan going.

If you know the power setting and the rate of descent then the rest is just scanning and small corrections. Hope it makes sense.

 

[dtuuri]

Hi guys, just wondering if someone could give me some advice.

The trick, SNOWBANK, is to break your flight into phases: takeoff roll before gear retraction, climbout after gear retraction, and so on until landing or making a go-around. There should be around eight phases. Each has a different engine failure procedure to follow. One of my phases is "Maneuvering for the approach/intercepting the final approach course." When entering that phase, any engine failure becomes less of a priority than intercepting the course. I literally delegate the emergency to my right arm on a workload-permitting basis while the rest of me concentrates on flying the plane. It handles the procedure when my CPU (brain) has spare time, in increments. Instead of rudder trim, use both feet on one rudder pedal. Save the trim for longer segments at higher power.

Btw, good post on the type rating for fun thread.

dtuuri

 

[SNOWBANK]

Thanks much everyone, I appreciate the advice and will be incorporating it next week.

 

[dtuuri]

Thanks much everyone, I appreciate the advice and will be incorporating it next week.

To clarify the rudder trim, if you trim for the lost engine when you don't really need to, then remove power as you begin to flare for landing--you'll be out of trim for landing. The rudder control will feel surprisingly wrong.

dtuuri

 

[Henning]

To clarify the rudder trim, if you trim for the lost engine when you don't really need to, then remove power as you begin to flare for landing--you'll be out of trim for landing. The rudder control will feel surprisingly wrong.

dtuuri

If you know it's coming it's no different than a crosswind landing. I have never had it be an issue. Besides, that's why I say, when you 'break out, start rolling out the trim.

Seriously folks are you going to fly half an hour holding 40-50lbs with your leg against 260-300+HP then fly an ILS to minimums and expect to have any finesse left? You guys must be freaking Hercules and go to the gym everyday, no way I could do it, and no way I would subject myself to the extra stress, nor would I expose my passengers to the extra risk of flying a plane that is trimmed to jump into a crash if I get a leg cramp. This is compete stupidity.

Are you in a turbine with hydraulic boost and you just have to rest your foot on the rudder that most likely will auto trim out the pressure on your foot anyway? WTF then, no big deal. In a high performance piston twin with none of these features it is complete idiocy not to use the rudder trim.

Here's a question, what does the POH say about using rudder trim?

 

[Henning]

The people I learned ME from were people who flew bombers in WWII, trim was drilled into me over and over.

 

[Francis A]

I don't know if some turbine or turbo props have an auto trim, but I can say that the last time I did B737-NG simulator, which has two hydraulic systems powering the rudder, it certainly needs trimming on one engine otherwise you leg start to shake like hell after a while from the pressure you have to hold. Cant say if this is the same on the real thing, never had to use it. Simulators have some differences to the real thing so it may be easier to hold rudder in with hydraulic pressure.

 

[dtuuri]

Seriously folks are you going to fly half an hour holding 40-50lbs with your leg against 260-300+HP then fly an ILS to minimums and expect to have any finesse left?

I don't think anybody said that. We're talking about losing an engine during the final phase of a flight with much reduced power. Not a lot of asymmetrical thrust there, so you don't need a lot of trim anyway. If you don't neutralize it, though, it'll feel unnatural when you chop the power.

dtuuri