Turn and Bank indicators.

[Mark Nestler]

I'm looking to replace a Turn and Bank indicator. However, their specifications list "With an 8 degree tilt" or no tilt or custom tilt. How would I determine which version would be correct for a Grumman AA5? Thanks.

 

[dmspilot]

I'm looking to replace a Turn and Bank indicator. However, their specifications list "With an 8 degree tilt" or no tilt or custom tilt. How would I determine which version would be correct for a Grumman AA5? Thanks.

Some aircraft came with slanted instrument panels, most notably early Mooneys. I don't know of any others off hand, though the "knee panel" in some Beechcraft might count. I don't think Grummans came with slanted panels, but your best bet is to use a level or check the part number of your existing instrument.

 

[Clip4]

Why not upgrade to turn coordinator? Both are listed in the parts manual.

 

[luvflyin]

Why not upgrade to turn coordinator? Both are listed in the parts manual.

I’ll bet he has a Turn Coordinator. A needle and ball, while sometimes called a Turn and Bank will give no indication of bank other than the rate of turn that results from bank. A Turn Coordinator will respond directly to Roll. @Mark Nestler ? What do you have? The Needle with the dog houses? Or the thing with wings?

 

[Der Fliegermeister]

I don't advise using a level since the airplane could be sitting wonky on the hangar floor.

Identical part number would be the simplest swap. Other than that, the parts manual or even maintenance manual may have the answer.

 

[Mark Nestler]

The plane is equipped with the indicator which has wings (and ball in the lower section).

 

[Clip4]

That’s a turn coordinator.
Turn and bank is needle and ball.

 

[luvflyin]

The plane is equipped with the indicator which has wings (and ball in the lower section).

Those don’t read ‘bank’ directly. What they do is detect the ‘roll.’ Once you neutralize and settle in to a ‘fixed’ bank you will no longer be rolling. At that point it is just reading the ‘rate of turn.’

 

[Mark Nestler]

OK, let me see if I have this straight. The turn coordinator wings only indicate roll. Once the established bank angle is attained and held, the wings return to the neutral position? I'm taking some instrument instruction and the instructed said I needed to have the turn coordinator looked at in an instrument shop. He could not tell if I was maintaining a standard turn, the wings were momentarily hitting the mark, and then returning to the neutral position (with minor gyration). So do I have an error in the turn coordinator or is that the way it should function?

 

[luvflyin]

OK, let me see if I have this straight. The turn coordinator wings only indicate roll. Once the established bank angle is attained and held, the wings return to the neutral position? I'm taking some instrument instruction and the instructed said I needed to have the turn coordinator looked at in an instrument shop. He could not tell if I was maintaining a standard turn, the wings were momentarily hitting the mark, and then returning to the neutral position (with minor gyration). So do I have an error in the turn coordinator or is that the way it should function?

No. Like I said, once you quit ‘rolling’ it reads only ‘rate of turn.’ The ‘wings’ will appear to be in a bank and unless you are very uncoordinated, you will be. But the ‘degree’ of bank will not be represented by the ‘wings.’ You could be in a somewhat steep bank, at a fast speed, turning at 3 degrees per second, the ‘wingtip’ will be on the mark. Or at a shallower bank at a slower speed, still turning at 3 degrees per second, the ‘wingtip’ will still be on the mark.

 

[Mark Nestler]

OK, so basically if I am in a steady 15 degree bank (at approx 115 kts) the turn coordinator (airplane) should be tilted close the standard rate turn mark and not bobbling around very much.

 

[dmspilot]

I don't advise using a level since the airplane could be sitting wonky on the hangar floor.

I don't advise using any tool improperly.

OK, let me see if I have this straight. The turn coordinator wings only indicate roll. Once the established bank angle is attained and held, the wings return to the neutral position? I'm taking some instrument instruction and the instructed said I needed to have the turn coordinator looked at in an instrument shop. He could not tell if I was maintaining a standard turn, the wings were momentarily hitting the mark, and then returning to the neutral position (with minor gyration). So do I have an error in the turn coordinator or is that the way it should function?

The gyro in a turn coordinator indicates turn rate and roll rate, while a turn-and-slip indicator which was also called a turn-and-bank indicator only indicates turn rate. But either instrument should show a steady deflection in a steady turn.

The "bank" part of "turn and bank" actually is referring to the ball. It's a confusing name that is best avoided.

 

[Der Fliegermeister]

I don't advise using any tool improperly.

PREACH!!! Lol precisely, my good fellow

 

[Dan Thomas]

The proper instrument is listed in the parts catalog for the airplane. If that isn't clear enough, you have to level the airplane in accordance with the service manual and then see if the instrument panel is vertical or at some angle off the perpendicular. The wrong instrument will give wrong readings, something not welcome when it comes time for your CPL or IFR flight test.

The turn-and-bank instrument has its gyro in a gimbal that is pivoted fore-and-aft. In that axis it only precesses in yaw, so it only shows turn rate. The turn coordinator has an angled gimbal, which makes it somewhat sensitive to roll, so that it starts indicating sooner as you start the turn, making is easier to nail a rate one or whatever.

 

[luvflyin]

OK, so basically if I am in a steady 15 degree bank (at approx 115 kts) the turn coordinator (airplane) should be tilted close the standard rate turn mark and not bobbling around very much.

If your ‘steady’ at a bank and steady on the rudder it shouldn’t bobble at all. I came up with 18 degree bank needed using a rough calculation based on True Airspeed to get Standard Rate turn

 

[Mark Nestler]

I pulled it out and ran it in my hand. Tried to keep it level and bank it while running. Groaned and whined and the miniature airplane was all over the place. It was made by Britain Industries which no one will rebuild anymore, so waiting for a replacement to arrive. The unit was stamped for vertical installation only, so that answered the 8 degree tilt question.

 

[luvflyin]

I pulled it out and ran it in my hand. Tried to keep it level and bank it while running. Groaned and whined and the miniature airplane was all over the place. It was made by Britain Industries which no one will rebuild anymore, so waiting for a replacement to arrive. The unit was stamped for vertical installation only, so that answered the 8 degree tilt question.

Cool, problem solved. Now don’t let us be catching you trying to sell a used turn coordinator that runs fine.

 

[Silvaire]

I don't advise using a level since the airplane could be sitting wonky on the hangar floor...

Well if you use a digital smart level, which are pretty cheap these days, you just zero it on the floor then you will be measuring the panel angle in reference to that so you'll get an accurate reading.

 

[Der Fliegermeister]

Well if you use a digital smart level, which are pretty cheap these days, you just zero it on the floor then you will be measuring the panel angle in reference to that so you'll get an accurate reading.

In two dimensions? And can you guarantee the airplane is true with those geometric planes?

The tolerance for mounting certain LRUs can be less than 2 degrees.

Grand scheme: probably doesn't matter much.

If someone wants it perfect (which I do and so do many of my customers) then the jacks come out.

But we're talking about a simple instrument swap. I point the group again to my initial post.

 

[Silvaire]

In two dimensions? And can you guarantee the airplane is true with those geometric planes?

Not sure what you mean. If he just wants to know the angle of the panel then zero the level in the longitudinal plane on the floor (or whatever is specified as the leveling datum) then place it vertically on the panel. If it's less than 90 then you have the angle. It's a simple instrument swap yes, but he wanted to know what "tilt" to specify when purchasing the replacement.

 

[MBDiagMan]

I pulled it out and ran it in my hand. Tried to keep it level and bank it while running. Groaned and whined and the miniature airplane was all over the place. It was made by Britain Industries which no one will rebuild anymore, so waiting for a replacement to arrive. The unit was stamped for vertical installation only, so that answered the 8 degree tilt question.

Pierce & Strait, I think that’s the name, in Tulsa rebuilds all the Britain stuff. They’re used a lot in the Mooneycommunity.