I hate my directional gyro

ircphoenix

ircphoenix

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ircphoenix
Did 3 1/2 hours of flying today. My DG precesses stupid fast. And while it's winding down after killing the master, I'm pretty sure I'm listening to the gyro screaming out in agony. And much like everything else in certificated aircraft, if I want to fix it, it's 1 AMU minimum.

I also hate whiskey compasses. Thinking of getting a vertical card compass and living with the DG until I win the lottery. The vertical card will only cost me 300 bucks plus a 50 dollar mount plus probably 200 hours of labor just because.

/rant
 
I had similar problems when I bought the 'kota. The compass was completely shot for whatever reason. I thought the DG was precessing but it was mostly problems with the compass. Had a sirs compass installed and I haven't looked back. That is one very accurate compass.
 
Clark1961 said:
I had similar problems when I bought the 'kota. The compass was completely shot for whatever reason. I thought the DG was precessing but it was mostly problems with the compass. Had a sirs compass installed and I haven't looked back. That is one very accurate compass.
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I'm thinking PAI 700.
 
VCC's are notoriously clunky. Too many gears. There was one in my 172 when I bought it. I finally took it out because it was "jerky" and "sticky." It was only 2 to 3 years old at the time.

I'm with Clark. When the current compass in my 182 goes tango uniform, I'm going with a sirs.

BTW, it looks like you can buy an OH'ed vacuum directional gyro for less than $500. Not much more than your VCC. And it sounds like it's a higher priority....
 
ircphoenix said:
Did 3 1/2 hours of flying today. My DG precesses stupid fast. And while it's winding down after killing the master, I'm pretty sure I'm listening to the gyro screaming out in agony. And much like everything else in certificated aircraft, if I want to fix it, it's 1 AMU minimum.

I also hate whiskey compasses. Thinking of getting a vertical card compass and living with the DG until I win the lottery. The vertical card will only cost me 300 bucks plus a 50 dollar mount plus probably 200 hours of labor just because.

/rant
Click to expand...

"After killing the master" That sounds more like the electric gyro in the TC may be the one doing the screaming, the DG is usually vacuum driven. What happens when you switch on the master and before you start the engine? If the TC gyro is failing you will hear it then.
 
I have a vertical card compass in my plane and love it compared to an old-style whiskey compass. My DG precesses too, and its quite annoying. I use the DG to a turn, but make most of my directional references to the vertical compass. I finally have a plan of attack for my IFR, will study for the written this winter, then hit the flying portion hard in the spring when the weather and daylight will be more cooperative. Plan on using the DG I have for it, just check it often.
 
+1 for sirs, installed mine years ago. don't even need the lighted version, tHe numbers and marks are so good you can read them in the dim light of the panel.
 
Replaced my vertical compass with a SIRS and couldn't be happier. Never gave me a lick of trouble where as my vertical compass was all over the place.
 
GRG55 said:
"After killing the master" That sounds more like the electric gyro in the TC may be the one doing the screaming, the DG is usually vacuum driven. What happens when you switch on the master and before you start the engine? If the TC gyro is failing you will hear it then.
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I hear the usual gyro winding down sound. There are some strange noises coming from the panel that don't sound like the normal gyros winding down sound that I'm used to in the 172s I've flown. Couldn't tell you exactly which one it is coming from, but I assumed it was the DG just because of the constant precession. Sometimes when I'm adjusting it in flight the thing jumps the moment I push in the knob. Don't know if it is normal, but all I have to compare it to is the 172's I trained in.
 
timwinters said:
VCC's are notoriously clunky. Too many gears. There was one in my 172 when I bought it. I finally took it out because it was "jerky" and "sticky." It was only 2 to 3 years old at the time.

I'm with Clark. When the current compass in my 182 goes tango uniform, I'm going with a sirs.

BTW, it looks like you can buy an OH'ed vacuum directional gyro for less than $500. Not much more than your VCC. And it sounds like it's a higher priority....
Click to expand...
I was looking at aircraft spruce and the only ones I saw there for 1/2 AMU were OH's for experimentals. Got a linky?
 
ircphoenix said:
I hear the usual gyro winding down sound. There are some strange noises coming from the panel that don't sound like the normal gyros winding down sound that I'm used to in the 172s I've flown. Couldn't tell you exactly which one it is coming from, but I assumed it was the DG just because of the constant precession. Sometimes when I'm adjusting it in flight the thing jumps the moment I push in the knob. Don't know if it is normal, but all I have to compare it to is the 172's I trained in.
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On shutdown all the gyros will be winding down. On start up when you switch on the master only the electric gyro(s) will be winding up before you start the engine. Usually only the TC is electric. So if you are getting a lot of unusual noise at that time it won't be from the vacuum operated gyro instruments; and usually the DG is vacuum operated. However, based on your description of how its behaving sounds like the DG is overdue for some love and attention.
 
ircphoenix said:
I was looking at aircraft spruce and the only ones I saw there for 1/2 AMU were OH's for experimentals. Got a linky?
Click to expand...

Depending on where you are it might be easier to pull the one you have an send it out for overhaul so you are reinstalling the same device with the same connections in the same locations behind the panel. There's a number of good shops that will OH instruments and the Piper or Cessna forums usually have threads (PoA might have one too from the past?). Rudy Aircraft instruments is one place that gets a lot of good mentions, although I have no direct experience with them. A 3" dia DG OH is $355 on their price list.
http://www.rudyaircraftinstruments.com/
 
This one is easy. Pull the old one and send it in on a oh exchange basis. Down time is zero for small amount in aviation speak. Hardest part is contorting yourself to get under there. Remove the seat and it's even easier.

I'm with ya, I absolutely hate the mechanical inaccuracy inherent to mechanical non slaved DGs. But I'm not gonna sink Aspen money for the privilege of magnetic slaving. I'll just keep twisting and go GPS track for heading if it all goes to hell in IMC. ATC won't care much anyways.
 
hindsight2020 said:
This one is easy. Pull the old one and send it in on a oh exchange basis. Down time is zero for small amount in aviation speak. Hardest part is contorting yourself to get under there. Remove the seat and it's even easier.

I'm with ya, I absolutely hate the mechanical inaccuracy inherent to mechanical non slaved DGs. But I'm not gonna sink Aspen money for the privilege of magnetic slaving. I'll just keep twisting and go GPS track for heading if it all goes to hell in IMC. ATC won't care much anyways.
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Fundamentally I guess it doesn't matter if it works well or not since I've got the 530 on board. But it drives me nuts. Add on top of that a whiskey compass with a bubble in it and a loose mount and I'm losing my mind.

Never train in an SP. It'll spoil you on any aircraft that you can actually afford.
 
Unit74 said:
I JUST installed one. I like it a lot. I don't like the whiskey compass' at all. I'm visual and bad at math. A whiskey was almost worthless to me.
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Yeah. I think you're the one whose post turned me on to them.

But now with all the SIRS love I'm doubting my choice... But the whole reverse direction thing on the floats constantly gets me screwed up.
 
What's a DG? is that thing they throw away when the G5 goes in?

Only half kidding.
 
Vertical card, but I've yet to use it really.

Slaved is the only way to go ;)
 
ircphoenix said:
Yeah. I think you're the one whose post turned me on to them.

But now with all the SIRS love I'm doubting my choice... But the whole reverse direction thing on the floats constantly gets me screwed up.
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Reason I replaced a perfectly good compass as soon as I got the plane in the shop. Effing hate whiskey compasses. Lead lag issues, visualization, math while trying to fly..... Eff that.

Also helps that it looks identical to the DG face.
 
Note of caution: We thought our DG processed too much a few years back, and it was vacuum system related, the DG behaved pretty normally after the whole system was checked carefully and the filter was changed (even though it looked to be in good condition, we somehow got a bad one).

Also I can't see where you'd spend an AMU to swap a DG... you don't need to buy new as others have pointed out.
 
RotorDude said:
Well, I am. I recently replaced my old turn coordinator gyro with an overhauled unit by AQI.
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Yeah, I know, some people have had good luck with them. Jesse likes them too. When I bought my airplane I sent every instrument into them for O.H. Literally, every one. In two or three years they were all sitting on my bookshelf...good looking paper weights.
 
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Unit74 said:
Effing hate whiskey compasses....visualization, math while trying to fly..... Eff that.

Also helps that it looks identical to the DG face.
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As I've posted here before:

For those concerned about the "reverse reading" of standard compasses, I have a mental trick that I use. I hope I can adequately explain this...along with the visual props that I just created...

So, you're flying along to the north and your DG looks like this:

dg-png.35020


Everything is oriented properly and it is easy to deduce that it would take a left turn to attain a 330 heading.

However, your compass looks like this (sort of):

dg2a-png.35021


And it might be easy to think that it'd actually take a right turn to attain that 330 heading.

But, if you simply visualize an arrow, starting at 330, going through the CL of the compass hub, then out the back side of the compass at the windscreen (which is the front of the airplane...an important detail) then life is good again and it's again easy to see that 330 is a left turn...not a right turn.

dg2b-png.35022


I've found this to be a very easy mental game to play with my compass and thus it becomes self correcting.

Hope this makes sense.
 
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timwinters said:
Yeah, I know, some people have had good luck with them. Jesse likes them too. When I bought my airplane I sent every instrument into them for O.H. Literally, every one. Wishing two or three years they were all sitting on my bookshelf...good looking paper weights.
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Beware of what you wish for?
 
Yeah...another auto correctism! It was supposed to say:

In two or three years they were all sitting on my bookshelf...good looking paper weights.

And is now fixed!
 
timwinters said:
As I've posted here before:

For those concerned about the "reverse reading" of standard compasses, I have a mental trick that I use. I hope I can adequately explain this...along with the visual props that I just created...

So, you're flying along to the north and your DG looks like this:

dg-png.35020


Everything is oriented properly and it is easy to deduce that it would take a left turn to attain a 330 heading.

However, your compass looks like this (sort of):

dg2a-png.35021


And it might be easy to think that it'd actually take a right turn to attain that 330 heading.

But, if you simply visualize an arrow, starting at 330, going through the CL of the compass hub, then out the back side of the compass at the windscreen, then life is good again and it's again easy to see that 330 is a left turn...not a right turn.

dg2b-png.35022


I've found this to be a very easy mental game to play with my compass and thus it becomes self correcting.

Hope this makes sense.
Click to expand...

Seems convoluted compared to "Left is always a lower number and right is higher ... unless you're turning through due north..."

I've never had trouble seeing that.
 
denverpilot said:
Seems convoluted compared to "Left is always a lower number and right is higher ... unless you're turning through due north..."

I've never had trouble seeing that.
Click to expand...

It's really not convoluted at all...at least not to me...rather it emphasizes that a compass reads backwards because your looking at the back side of it instead of the front side and because of that the dial is stenciled 180 degrees out of whack.

What's convoluted are my explanations! English is my second language you know.

Another fix, you could mount a ship's compass on the floor between the seats. They're not "reverse reading." :)

IMG_0281.JPG
 
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timwinters said:
It's really not convoluted at all...at least not to me...rather it emphasizes that a compass reads backwards because your looking at the back side of it instead of the front side and because of that the dial is stenciled 180 degrees out of whack.

What's convoluted are my explanations! English is my second language you know.

Another fix, you could mount a ship's compass on the floor between the seats. They're not "reverse reading." :)

View attachment 48634
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I got it. I just haven't ever had a problem with comparing current heading to the heading I want and knowing that's left if lower and right if higher. Don't really have to care which way the compass swings, just check it's going up or down in number as appropriate as a cross-check and then level on the new heading. (With all the usual compass fun for leading north and lagging south applied of course -- course, get it? Ha... )
 
$360 to overhaul. http://flyaqi.com/gyro.htm

I exchanged a few instrument with them and couldn't be more happy. They work great and fully trust them. Get with your A&P and install it with him to save some money and learn how your plane works. It's not that hard actually.

Vertical card compass I put in my plane as well
Best money spent love it! I installed that myself as well under supervision from my mech.
 
I got lucky, my plane had the PAI 700 already installed when I bought it. Now I just need to replace my DG with one that has a heading bug for IFR training. I'm going with AQI refurb. I'm wondering if they'll give me partial exchange for the old one. With my luck...probably not.
 
timwinters said:
Are you saying that a VCC doesn't have lead & lag issues?

<whistles>
Click to expand...

Yes

The PAI 700 is eddy current dampened. Flew today. No lead, no lag. Rock solid. Don't know the physics behind it, but it works.
 
Timbeck2 said:
I got lucky, my plane had the PAI 700 already installed when I bought it. Now I just need to replace my DG with one that has a heading bug for IFR training. I'm going with AQI refurb. I'm wondering if they'll give me partial exchange for the old one. With my luck...probably not.
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Hey Becky... you like the PAI?
 
That's all great stuff. Or just install a PAI 700 and make it stupid easy. No effing reasons to try and waste brain power on this as single pilot ops are already taxing. But, if those die hard whiskey compass boys don't need that fancy stuff, I guess they can hang out at the EAA hangar and tell WW II stories with the rest of them.

timwinters said:
As I've posted here before:

For those concerned about the "reverse reading" of standard compasses, I have a mental trick that I use. I hope I can adequately explain this...along with the visual props that I just created...

So, you're flying along to the north and your DG looks like this:

dg-png.35020


Everything is oriented properly and it is easy to deduce that it would take a left turn to attain a 330 heading.

However, your compass looks like this (sort of):

dg2a-png.35021


And it might be easy to think that it'd actually take a right turn to attain that 330 heading.

But, if you simply visualize an arrow, starting at 330, going through the CL of the compass hub, then out the back side of the compass at the windscreen (which is the front of the airplane...an important detail) then life is good again and it's again easy to see that 330 is a left turn...not a right turn.

dg2b-png.35022


I've found this to be a very easy mental game to play with my compass and thus it becomes self correcting.

Hope this makes sense.
Click to expand...
 
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