Uncoordinated ILS

flyboy04

Well-Known Member
I had a flight today that was unsatisfactorily complete, because it was a single engine ILS and the ball on the turn coordnator wasnt was about a ball and a half off. I held the glideslope, localizer and airspeed like a champ, i guess i just left the turn coordinator out of my scan. So you mutli engine instructors out there help me, is this grounds for a unsat on a checkride, because i sure dont want to make the same mistake on the FAA ride. I think if i was the isntructor i would have completed it with no questions, im interested to see what jet careers instructors will say.
 

EatSleepFly

Well-Known Member
I'm not an MEI, but my $.02 anyways...

You can be spot on the LOC, and GS but being uncoordinated while single engine is an NTSB report waiting to happen.

No worries though, you can obviously fly a perfect uncoordinated ILS, now all you have to do is go up once, shoot another SE ILS and kick in a little more rudder this time!
 

MikeD

Administrator
Staff member
[ QUOTE ]
I had a flight today that was unsatisfactorily complete, because it was a single engine ILS and the ball on the turn coordnator wasnt was about a ball and a half off. I held the glideslope, localizer and airspeed like a champ, i guess i just left the turn coordinator out of my scan. So you mutli engine instructors out there help me, is this grounds for a unsat on a checkride, because i sure dont want to make the same mistake on the FAA ride. I think if i was the isntructor i would have completed it with no questions, im interested to see what jet careers instructors will say.

[/ QUOTE ]

If you're descending on an ILS single engine, the ball isn't going to ALWAYS be displaced the same way. As you reduce power in the descent, there's less need for zero sideslip into the good engine, so the ball WILL not be in the same place as it would if you were on a single-engine go-around/climbout.

So freaking what if you left the ball out of your scan, the important thing is to have a good feel for the aircraft and whether it's maintaing coordinated flight. That's at a minimum. Do your best to incorporate the turn/slip indicator, but your primary reference is flying the approach on the ILS; like I said, with the reduced power, you don't have to worry about the yaw as much. If you flew the LOC/GS and kept a/s good, then you were flying acceptable correction into the good engine.

Big picture items:

1. Did you fly the plane/maintain control? Did you have adequate counter-yaw applied?

2. Was the approach within parameters?

3. Did you exercise good judgement and was the maneuver safe?

That's all that any examiner worth their salt should be looking for.,
 

viper548

Well-Known Member
The zero sideslip shouldn't be that important on an ILS approach. I wouldn't give an unsat. on an approach for not being in the zero sideslip. However, I would if it were at a high power setting.

When I got typed in the Citation, the instructor insisted that the ball remained centered during SE operations because it's easy to become confused when flying in the zero sideslip condition. Then again jets have much better climb performance on one engine.
 

MikeD

Administrator
Staff member
[ QUOTE ]


When I got typed in the Citation, the instructor insisted that the ball remained centered during SE operations because it's easy to become confused when flying in the zero sideslip condition. Then again jets have much better climb performance on one engine.

[/ QUOTE ]

Agree that correction isn't needed at lower power settings like when descending down the GS.

Not only that, but I would venture that the Citation is nearly centerline thrust, much like the F-15 would be. Is Vso higher than Vmc in the Citation?
 

IrishSheepdog

Sitting in the median
We were told to keep the wings level and ball centered flying single engine in the Saab since best performance is at 2 degrees bank, however a gross decrease in performance is found at 4-5 degrees of bank. So it's easier to fly with wings level (that's how the autopilot does it anyways) single engine.

I'd suggest just working on maintaining the zero sideslip throughout the approach. While you are scanning the needles, heading, pitch, etc., keep an eye on the turn coordinator. Should you decide to break off the approach (high, not talking a low altitude go around which probably would result in a problem), you'll want to be in zero sideslip.
 

sixpack

New Member
[ QUOTE ]
... was about a ball and a half off...

[/ QUOTE ]
I think the issue might be that the plane was very uncoordinated. A ball and a half off could be bad either way. Either way, you're in a slip and will have to add more power than necessary to hold the glideslope. If you need to go missed, this slip/drag condition will significantly reduce your climb performance.

When I teach engine-out in a multi, I like to have the student do turns with one engine. I teach them to keep the ball split on the heavy foot side.
 

ananoman

New Member
You said "and the ball on the turn coordnator wasnt was about a ball and a half off" and I am confused (by the 'wasnt was' part). Are you saying the ball wasn't about a ball and a half out toward the good engine? I am not sure why your instructor would want this. At full power, zero sideslip occurs at about 2-3 degrees of bank, with the ball 1/2 to 3/4 out toward the good engine. A ball and a half out would be an uncoordinated condition (not enough rudder).

As you reduce power and descend, there is less assymetric thrust, so he ball will be more toward the center. If you have a feathered engine and descend with the good engine close to the setting for 'zero thrust', your ball will be centered, as no assymetric thrust is being generated. It could be argued that if you pull your good engine to idle and let it windmill, the ball should be slightly out toward the feathered engine to stay coordinated and counter the 'assymetric drag' produced by the windmilling prop.

On an ILS, you are not at full power, so I see no need to keep the ball much out toward the good engine. If you have a yaw string on your plane, (I suggest you put one on for your next flight, just to experiment) you will see that you are coordinated when the ball is very close to being centered during a partial power descent.
 

flyboy04

Well-Known Member
My apologies, i didnt mean to be confusing. The ball was out a ball and half, and without a doubt it was unsat because i was uncoordinated, i just wasnt sure if that was part of commercial PTS, i was under the impression you were judged more on altitude, course, and airspeed.
 

EatSleepFly

Well-Known Member
I think its more the principle of it. Sure, it may not be as big a deal on an ILS as say, on takeoff or whatever, but maybe the examiner just wanted you to be more aware of the coordination in general. Good luck on the FAA ride!
 

av8rmsu

Well-Known Member
If the a/c has a yaw string on the windshield....I think that would give you a better idea of how much of a sideslip you are actually in....I could be wrong (I'm taking my ME checkride next week).
 

B767Driver

New Member
It's a been a while since I've seen the ME PTS, but a ball and a half is a pretty aggregious error. My recollection is that all engine out operations reguire the attainment of zero sideslip flight.

Now, I'm going to go and look it up to see if that's in fact the case!
 
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