Spinning Horizon

[Mike Adams]

Here's a weird one I'd never heard of before but maybe one of you guys can
explain. I installed a new attitude indicator last week and went out for a
test flight yesterday. It's just a plain vanilla R C Allen vacuum AI. Well,
it worked great on the flight - erected quickly, and nice and stable in
flight. But then when I shut down, and the gyro was spinning down, the
horizon started spinning, fairly rapidly - maybe one revolution per second.
Then of course it eventually stopped as the gyro spun down.

So, has anyone ever heard of this? is it indicative of a problem? It's a
factory overhauled unit that I can pull out and take back to the shop if
necessary, or I can learn to live with it if it's harmless.

Thanks, and happy holidays all,

Mike

[Aaron Coolidge]

Mike Adams > wrote:

: So, has anyone ever heard of this? is it indicative of a problem? It's a
: factory overhauled unit that I can pull out and take back to the shop if
: necessary, or I can learn to live with it if it's harmless.

I also have an RC Allen gyro horizon. It does not do this.

My old gyro horizon did this on spin-down, more and more as it wore out.
Eventually it did it all the time. It was an Edo-Aire. I believe it
is indicative of bad bearings in the gyro mechanism. Does the gyro make a lot
of noise as it spins down, or can you feel vibration with your fingers
on the front glass? My worn-out gyro did both of these in an increasing
amount each flight.

--
Aaron Coolidge (N9376J)

[Mike Adams]

Not really. It was quite smooth and the spin down took quite awhile. I did
notice a slight tapping or clicking noise with each revolution of the
horizon.

Mike

Aaron Coolidge > wrote
> Does the gyro
> make a lot of noise as it spins down, or can you feel vibration with
> your fingers on the front glass?

[G.R. Patterson III]

Mike Adams wrote:
>
> So, has anyone ever heard of this? is it indicative of a problem?

I also have an RC Allen AI. It does not do this.

George Patterson
Great discoveries are not announced with "Eureka!". What's usually said is
"Hummmmm... That's interesting...."

[Stu Gotts]

Mike;
Don't get upset about this, just send it back! If you don't you'll be
kicking yourself in the ass when it goes tits up the day after the
warranty expires.


On Wed, 24 Dec 2003 17:58:48 GMT, Mike Adams >
wrote:

>Here's a weird one I'd never heard of before but maybe one of you guys can
>explain. I installed a new attitude indicator last week and went out for a
>test flight yesterday. It's just a plain vanilla R C Allen vacuum AI. Well,
>it worked great on the flight - erected quickly, and nice and stable in
>flight. But then when I shut down, and the gyro was spinning down, the
>horizon started spinning, fairly rapidly - maybe one revolution per second.
>Then of course it eventually stopped as the gyro spun down.
>
>So, has anyone ever heard of this? is it indicative of a problem? It's a
>factory overhauled unit that I can pull out and take back to the shop if
>necessary, or I can learn to live with it if it's harmless.
>
>Thanks, and happy holidays all,
>
>Mike

[Doug]

My RC Allen AI did that when it was new also. It has lasted another
1000 hours! I called the guy who supplied it, he said go ahead and use
it till warranty expiration is near, then if it still does it, send it
back. It has stopped doing this. It also, very occasionally did
another weird thing. It would erect upsidedown! Then spend about a 45
minutes gradually righting itself. This is no BS, really did that,
three times at least. If it had been an IFR trip, I couldn't have
taken off. As it was, I just flew and watched in amusement. Gyros are
weird sometimes.

Mike Adams > wrote in message news:<stkGb.37748$m83.27355@fed1read01>...
> Here's a weird one I'd never heard of before but maybe one of you guys can
> explain. I installed a new attitude indicator last week and went out for a
> test flight yesterday. It's just a plain vanilla R C Allen vacuum AI. Well,
> it worked great on the flight - erected quickly, and nice and stable in
> flight. But then when I shut down, and the gyro was spinning down, the
> horizon started spinning, fairly rapidly - maybe one revolution per second.
> Then of course it eventually stopped as the gyro spun down.
>
> So, has anyone ever heard of this? is it indicative of a problem? It's a
> factory overhauled unit that I can pull out and take back to the shop if
> necessary, or I can learn to live with it if it's harmless.
>
> Thanks, and happy holidays all,
>
> Mike

[Roger Halstead]

On 24 Dec 2003 17:37:10 -0800, (Doug)
wrote:

>My RC Allen AI did that when it was new also. It has lasted another
>1000 hours! I called the guy who supplied it, he said go ahead and use
>it till warranty expiration is near, then if it still does it, send it
>back. It has stopped doing this. It also, very occasionally did
>another weird thing. It would erect upsidedown! Then spend about a 45
>minutes gradually righting itself. This is no BS, really did that,
>three times at least. If it had been an IFR trip, I couldn't have
>taken off. As it was, I just flew and watched in amusement. Gyros are
>weird sometimes.
>

Mine doesn't spin, but will sometimes wobble for a minute or two if
the plane is really cold inside. I need to put a heater under the
panel to go with the tanis on the engine.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair?)
www.rogerhalstead.com

>Mike Adams > wrote in message news:<stkGb.37748$m83.27355@fed1read01>...
>> Here's a weird one I'd never heard of before but maybe one of you guys can
>> explain. I installed a new attitude indicator last week and went out for a
>> test flight yesterday. It's just a plain vanilla R C Allen vacuum AI. Well,
>> it worked great on the flight - erected quickly, and nice and stable in
>> flight. But then when I shut down, and the gyro was spinning down, the
>> horizon started spinning, fairly rapidly - maybe one revolution per second.
>> Then of course it eventually stopped as the gyro spun down.
>>
>> So, has anyone ever heard of this? is it indicative of a problem? It's a
>> factory overhauled unit that I can pull out and take back to the shop if
>> necessary, or I can learn to live with it if it's harmless.
>>
>> Thanks, and happy holidays all,
>>
>> Mike

[Nathan Young]

(Doug) wrote in message >...
> My RC Allen AI did that when it was new also. It has lasted another
> 1000 hours! I called the guy who supplied it, he said go ahead and use
> it till warranty expiration is near, then if it still does it, send it
> back. It has stopped doing this.

Granted I know nothing about the failure modes of an RC Allen AI, but
this seems like terrible advice from RC Allen. If nothing else, it is
setting them up for a legal suit.

Reading through the lines of the reps statement... The rep is saying
there is something wrong with a gyro that exhibts this behavior, ie
return it if it still exhibiting this behavior near the warranty
expire date. Then he/she suggested to continue using it in its
current state.

Imagine if the gyro then dies during IMC flight causing an accident...
I'm not a lawyer, and I typically frown on aviation lawsuits (ie why
couldn't the pilot fly partial panel) - but this seems like a slamdunk
case for the grieving relatives. The rep admitted the gyro was bad,
then told the pilot to continue using it.

-Nathan

[G.R. Patterson III]

Nathan Young wrote:
>
> Reading through the lines of the reps statement... The rep is saying
> there is something wrong with a gyro that exhibts this behavior, ie
> return it if it still exhibiting this behavior near the warranty
> expire date.

No, the rep is saying "This is normal behavior for a new or rebuilt unit, but it
shouldn't keep doing this for very long."

George Patterson
Great discoveries are not announced with "Eureka!". What's usually said is
"Hummmmm... That's interesting...."