Turn & bank indicator indicating opposite turns

Irish_Armada

Irish_Armada

Pre-takeoff checklist
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Oct 8, 2011
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Irish Armada
What would cause a turn & bank indicator to indicate opposite direction turns? E.g. when turning right, it shows a turn to the left and vice versa. The ball/inclinometer indicates correctly, but the direction needle is totally opposite. :dunno: :confused:
 
There's a very simple answer to this - it's busted. The gyro is not spinning.
 
Do you mean it is going opposite of the way the needle usually goes, or do you mean it goes opposite of the way you think it should go in comparison to the winged plane thingie you're used to? If the latter, that is normal, AN type gyros take some getting used to especially when you have a mixed TC and AI and you watch them react differently.
 
Henning said:
Do you mean it is going opposite of the way the needle usually goes, or do you mean it goes opposite of the way you think it should go in comparison to the winged plane thingie you're used to? If the latter, that is normal, AN type gyros take some getting used to especially when you have a mixed TC and AI and you watch them react differently.
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I mean if I'm turning left during taxi or turning left in flight, the needle is going toward the "doghouse" on the right, instead of the left. Same thing the other way, if I'm turning right, the needle is going left. The ball is doing what it's supposed be doing, but the needle is pointing the opposite direction. I also thought if the gyro was busted, the needle would just sit there with no directional indication, but instead it seems to be doing it somewhat accurately, just in the opposite direction...
 
Irish_Armada said:
I mean if I'm turning left during taxi or turning left in flight, the needle is going toward the "doghouse" on the right, instead of the left. Same thing the other way, if I'm turning right, the needle is going left. The ball is doing what it's supposed be doing, but the needle is pointing the opposite direction. I also thought if the gyro was busted, the needle would just sit there with no directional indication, but instead it seems to be doing it somewhat accurately, just in the opposite direction...
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If the needle is going opposite the turn, the unit is broke. Exactly what's wrong isn't a significant issue since it's nothing you can fix yourself. Send it to an instrument shop for repair.
 
Irish_Armada said:
I mean if I'm turning left during taxi or turning left in flight, the needle is going toward the "doghouse" on the right, instead of the left. Same thing the other way, if I'm turning right, the needle is going left. The ball is doing what it's supposed be doing, but the needle is pointing the opposite direction. I also thought if the gyro was busted, the needle would just sit there with no directional indication, but instead it seems to be doing it somewhat accurately, just in the opposite direction...
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That's the way an AN gyro works, with it the background stays with the plane and the needle stays perpendicular to the horizon AS SENSED IN RATE OF TURN, that's why it moves over in taxi. In the modern gyro the plane will represent the bank against the background, in the AN gyro the background is the plane and needle points 'up' within its range of motion.

This is why flying an old set of AN gyros in IMC when all you are used to is modern gyros can be a bad thing. It's part of what brought that Russian jet down a few months ago.
 
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Ron Levy said:
If the needle is going opposite the turn, the unit is broke. Exactly what's wrong isn't a significant issue since it's nothing you can fix yourself. Send it to an instrument shop for repair.
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Agreed. I was just thinking now that if the gyro were totally busted and the needle moving freely, that it could have been indicating opposite turns just based on the centrifugal force. Either way, I think it's time for an upgrade to a turn coordinator.
 
Henning said:
That's the way an AN gyro works, with it the background stays with the plane and the needle stays perpendicular to the horizon AS SENSED IN RATE OF TURN, that's why it moves over in taxi. In the modern gyro the plane will represent the bank against the background, in the AN gyro the background is the plane and needle points 'up' within its range of motion.

This is why flying an old set of AN gyros in IMC when all you are used to is modern gyros can be a bad thing. It's part of what brought that Russian jet down a few months ago.
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I think Henning is confusing attitude indicators with turn rate indicators. Even if he isn't, it's not relevant to the issue under discussion. There was never a turn rate indicator which worked as he describes -- they've always had the needle moving in the direction of the turn with the doghouses fixed in the background. There were once attitude indicators where the little airplane against the background moved rather than the background moving and the little airplane was fixed, but that's another story entirely (and one which was considered a contributing factor in the Buddy Holly/Richie Valens/Big Bopper accident) over 50 years ago.
 
I agree with C'Ron. What Henning is describing is historical difference in ATTITUDE gyros. It was infact, a contributing factor to the Buddy Holly/Big Bopper/Richy Valens crash.

The turn and bank measures the deflection of a (mostly) fixed gyro attempting to precess due to the turn. It's broke. It's quite possible that someone wired up the thing to the power backwards and it's spinning the wrong way which will cause exactly this problem.
 
flyingron said:
It's quite possible that someone wired up the thing to the power backwards and it's spinning the wrong way which will cause exactly this problem.
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That there is it. They use two wires, no ground. Easy to get wrong. But the electronic regulator in it wouldn't work right.

Dan
 
Dan Thomas said:
That there is it. They use two wires, no ground. Easy to get wrong. But the electronic regulator in it wouldn't work right.

Dan
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Okay thanks guys, we will look into that first.
 
A picture might be worth 1000 words.

turn22.gif


This airplane is in a standard rate turn to the left. Is your T&B indicating the opposite?
 
I would give Aircraft Quality Instruments a call, they most likely have a unit they can just ship you that's overhauled and the same thing. You ship yours back. If not they can turn around yours quite quickly.

It'll cost you about $300 for an exchange.

As far as I'm concerned their stuff is as good as new. Never been disappointed with anything they've overhauled.

http://www.flyaqi.com/
 
kgruber said:
A picture might be worth 1000 words.

turn22.gif


This airplane is in a standard rate turn to the left. Is your T&B indicating the opposite?
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Maybe the pic is unclear??? How does that show standard rate?
 
Jaybird180 said:
Maybe the pic is unclear??? How does that show standard rate?
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The needle is deflected to the left mark which is a 2 minute standard rate left turn. It's a rate instrument, not a bank.

The fact that it's a "rate" instrument never seems to click for people until I make them hold the wings level and turn with rudder.
 
Here's a simple YouTube video. If the gyro is not turning it's just simply trying to stay level when you turn. Is it vacuum or electric?

First things to check are:

Breaker
wires
vacuum hose
vacuum pump or venturi tube

Simple Rate Gyro Video
 
kgruber said:
A picture might be worth 1000 words.

turn22.gif


This airplane is in a standard rate turn to the left. Is your T&B indicating the opposite?
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Thanks. Yes the opposite. So mine would be showing this indication while turning/banking/taxiing right. My sixth sense tells me its broken....
 
Irish_Armada said:
Thanks. Yes the opposite. So mine would be showing this indication while turning/banking/taxiing right. My sixth sense tells me its broken....
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When you turn your master on, you should hear it spinning up, if you hear that I would pull it and do an exchange with Aircraft Quality Instruments. It'll be like new, take no time at all, and you'll do it while spending minimal money. IMO there is no point in buying a newer one.

If you don't hear it spinning up when you turn your master on I would first ensure that it is in fact receiving power before assuming it has failed.
 
jesse said:
...If you don't hear it spinning up when you turn your master on I would first ensure that it is in fact receiving power before assuming it has failed.
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Well actually the first thing to do is determine if it's an electric T&B because if it's vacuum it ain't gonna do anything when you turn the master on.
 
Silvaire said:
Well actually the first thing to do is determine if it's an electric T&B because if it's vacuum it ain't gonna do anything when you turn the master on.
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True, but it's a steam gauge Cherokee. It's electric. Either way he's going to need an A&P to sign this off who will figure this out in about five minutes.
 
I've never seen a vacuum T&B on any airplane with a vacuum pump. The only ones I've seen were on planes with venturies to power the vacuum instruments, and a separate one for the T&B from the AI. Reason is the FAA requires an independent power source for the turn rate indicator versus the AI. I suppose one could have a vacuum pump-powered T&B with an electric AI, but I've never seen that.

BTW, I can't imagine how a plane could get its T&B wired backwards as described above -- that would require a really poor QA program by both the mechanic who did the work and the pilot who next flew it. Unless someone was tinkering with the wires immediately before the OP flew it, I can't imagine this happening and not being seen and squawked.
 
weirdjim said:
What electronic regulator?

Jim
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Some cores I've opened had a small circuit board in them. Those were turn coordinators, not T&Bs, though. What do they use for speed regulation to get the two-minute turn accurate? Centrifugal switches, maybe?

Dan
 
Ron Levy said:
Unless someone was tinkering with the wires immediately before the OP flew it, I can't imagine this happening and not being seen and squawked.
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Just got out of annual.
 
Well we pulled the T&B and low and behold the wires were backwards. Rewired and the thing worked like normal on taxi test. Problem solved, live and learn. Thanks all!:thumbsup:
 
Irish_Armada said:
Well we pulled the T&B and low and behold the wires were backwards. Rewired and the thing worked like normal on taxi test. Problem solved, live and learn. Thanks all!:thumbsup:
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And of course the "regulator" was nowhere to be seen. THere ARE NO REGULATORS in civilian single-voltage instruments. YOur military background notwithstanding, we do NOT use regulators in civilian instruments.

THanks,

Jim
 
Irish_Armada said:
Well we pulled the T&B and low and behold the wires were backwards. Rewired and the thing worked like normal on taxi test. Problem solved, live and learn. Thanks all!:thumbsup:
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Okay you've got to explain to me why on Earth the T&B wiring was altered during an annual inspection :dunno:
 
Henning said:
Would the radios work? I remember a guy letting all the magic smoke out of the radios doing that.
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I may or may not have been that guy, but I don't think I ever posted to this forum about a recent escapade I had that involved some magic smoke.

I'll post it as a new thread and link to it here.
 
jesse said:
True, but it's a steam gauge Cherokee. It's electric. Either way he's going to need an A&P to sign this off who will figure this out in about five minutes.
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I would have thought a PP could fix this under the "plug and play" rules.
 
The harness on most Needle-Ball gauges is pretty simplistic. It's usually just two pins. If the mechanic decides that the needs to remove the TI to get to something (in fact, I dropped my TC the other day so I could get to the pitot line on my ASI) it's quite possible to screw up reconnecting it. Fortunately the Needle-Ball is an incredibly simple device. There's nothing in it other than a motor which will quite happily run with the power reversed.

It always bothers me when people call the Turn Indicator a Turn and Bank. Turn and Slip is closer. It really doesn't show bank directly. Even a turn coordinator doesn't show bank (it shows RATE OF BANK in addition to the turn).
 
flyingron said:
The harness on most Needle-Ball gauges is pretty simplistic. It's usually just two pins. If the mechanic decides that the needs to remove the TI to get to something (in fact, I dropped my TC the other day so I could get to the pitot line on my ASI) it's quite possible to screw up reconnecting it. Fortunately the Needle-Ball is an incredibly simple device. There's nothing in it other than a motor which will quite happily run with the power reversed.

It always bothers me when people call the Turn Indicator a Turn and Bank. Turn and Slip is closer. It really doesn't show bank directly. Even a turn coordinator doesn't show bank (it shows RATE OF BANK in addition to the turn).
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Yeah I think turn and slip is what's it's called but the actual unit says Turn and Bank on it.

We did a number of upgrades in the panel during the annual (this was our first annual since purchase back in December so it was a pretty hefty one) and our guy pulled the unit out to get to something else and accidentally rewired it backwards when he put it back in. That's why you follow the checklist on taxi ... which showed total opposite movement. It took less than an hour to swap the wires and now its working like normal. :D
 
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