AOA Malfunction

[EchoMax]

We inherited N943RW "The Gypsy Rose", a beautifully maintained and equipped 1966 E, from the late Bob Belville.

Bob installed a CYA100 AOA indicator and was enthusiatic about it.  It is a mechanical windvane type, but it no longer works reliably.

Is there some lubricant that would free it up, because I think it is a mechanical problem, or would a replacement do the trick, if I can find one?

For any AOA haters out there, yes, it lands just fine without one.

[LANCECASPER]

On 10/21/2023 at 5:10 PM, EchoMax said:

We inherited N943RW "The Gypsy Rose", a beautifully maintained and equipped 1966 E, from the late Bob Belville.

Bob installed a CYA100 AOA indicator and was enthusiatic about it.  It is a mechanical windvane type, but it no longer works reliably.

Is there some lubricant that would free it up, because I think it is a mechanical problem, or would a replacement do the trick, if I can find one?

For any AOA haters out there, yes, it lands just fine without one.

This thread may get you headed in the right direction:

https://www.beechtalk.com/forums/viewtopic.php?f=21&t=216292

[EchoMax]

I have reached out to Rip Quinby on BeechTalk.  Apparently, his company, or at least this product, is no more.

The Alpha Systems AOA was suggested by some as a replacement.

[KSMooniac]

I have an Alpha system with the Eagle display mounted on my glareshield as far forward as I could put it, and love it.  Great unit.

[Pinecone]

Which diplay did you go with?

I am looking at putting one in during my avionics upgrade.  I got used to an AOA readout in the T-38 and A-10.  I like the Alpha Eagle as it is a similar display to the USAF one.

[KSMooniac]

I got the original Eagle version:  Eagle Kit | Alpha Systems AOA with the "boxy" indicator and put it on top of my glareshield, biased to the right of the pilot view, just left of the centerline.  I didn't want it to interfere with my peripheral vision to the left at touchdown, and it works perfectly when looking straight ahead on final.  If choosing today, I might consider the HUD version instead, but I'm very happy with what I have.  I also skipped the heated pitot option as my thoughts were if I were iced-up, then the calibration would be off so much that the indications would be wrong/useless/dangerous so there is no need to heat their pitot probe on an un-protected airframe.  If I had a TKS bird, then it would make sense.

My opinion is that AOA is far less useful if installed on the panel as your eyes should not be there when on final.  It should stand alone and be easy to interpret with a quick glance while looking outside.

 

[Pinecone]

Thanks.

In the jets I flew, the AOA was on the left canopy bow.  So perfect when doing an overhead turning approach.  But still good for a straight in.  Probably put it where you have yours.

I agree that AOA on the panel is less useful.   The times when you need it the most, you are looking outside.

[philiplane]

I have a uAvionix AV20-S AOA, and it works very well. I plan to add the AOA option to my Aspen EFD Pro Max as well, just for fun. I was never impressed by the other AOA systems that relied upon anything other than a true AOA vane for sensing. Of course, the vane type of AOA systems are not available for light aircraft, due to $$$$$.

[Pinecone]

I wonder about AOA systems that don't add any sensing probe.

I have the Aspen AOA enabled (the plane came that way).  I find it usless.  Too small and out of view.

I am going to have the Alpha system installed.  I am a great believer in AOA.

[A64Pilot]

What is it you guys do with an AOA? Do you ever fly that close to the ragged edge of a stall?

I’ve flight tested them for crop dusters and besides the fact that two are needed, one for each wing as the most likely, and worst time for a stall is turning, where there is a different amount of lift on the two wings. Assuming you’re in trim the wing away from the turn will stall first. If your turning left the right wing will stall.

I came out with the conclusion that for a straight winged GA aircraft that they are essentially a toy. 

What I did find out through testing was that for a maneuvering aircraft that’s nibbling at the edge of a stall that mounting the trim ball on top of the glareshield costs nothing yet was more valuable than AOA, it’s being out of trim while maneuvering that will “get” you, having the ball in your direct line of sight was valuable, because many pilots when finding the turn isn’t as tight as they need it will subconsciously use rudder to tighten it, and that of course can “get” you.

[KSMooniac]

I use mine for final approach speed control... fly the indicator regardless of weight and it works very well.  No need to make any weight calcs prior to landing to calculate VREF.  (Yes, I know it doesn't move much in our planes, but solo and low fuel to fully loaded is quite a bit different.)

In an emergency situation, the "bitchin' Betty" portion of it that goes over an unswitched audio panel input would be helpful as well to keep from getting too slow in a glide while looking for a place to land.  Your eyes should definitely be outside all the time in that scenario and not looking at the ASI, so I think there is a safety improvement.

[Pinecone]

27 minutes ago, A64Pilot said:

What is it you guys do with an AOA? Do you ever fly that close to the ragged edge of a stall?

I’ve flight tested them for crop dusters and besides the fact that two are needed, one for each wing as the most likely, and worst time for a stall is turning, where there is a different amount of lift on the two wings. Assuming you’re in trim the wing away from the turn will stall first. If your turning left the right wing will stall.

I came out with the conclusion that for a straight winged GA aircraft that they are essentially a toy. 

What I did find out through testing was that for a maneuvering aircraft that’s nibbling at the edge of a stall that mounting the trim ball on top of the glareshield costs nothing yet was more valuable than AOA, it’s being out of trim while maneuvering that will “get” you, having the ball in your direct line of sight was valuable, because many pilots when finding the turn isn’t as tight as they need it will subconsciously use rudder to tighten it, and that of course can “get” you.

Uuh, if you are in coordinated flight, both wings are making the same lift and there is no way to tell which one will stall first.

AOA tells you where you are in relation to stall.  Airspeed does not, as it stall airspeed varies by weight.  

[Rick Junkin]

The most useful indication on an AOA indicator is the "on speed" indication. Get it there and keep it there until roundout and flare, or perhaps slow down a bit before roundout depending on where you've decided to calibrate "on speed". 1.3 or 1.2 Vs0 is a good starting point.

What made it really useful in the jets I flew was the AOA tone. A slow rate beeping tone approaching on-speed AOA, a steady tone on-speed, and a fast rate beeping tone when the AOA exceeded on-speed. The experimental G3X AOA system just added the capability to turn on an on-speed tone. The certified system gives a varying tone depending on how far you've exceeded on-speed AOA but it doesn't allow for a tone indicating on-speed. That probably won't change due to its mental equivalency with the stall horn and the FAA probably won't authorize it because of the confusion it could cause, based on the behavior of legacy stall warning systems in GA airplanes. I'll be very happy if I'm wrong about that.

My point is "pull to the tone" was an instructional direction for how to fly the curvilinear base to final turn of an overhead pattern on-speed. The visual indicator was there, but the tone was gold.

Cheers,
Rick

[Pinecone]

Hmm, the airplanes I flew with AOA did not have an on speed tone.  The A-10 had a max performance AOA tone and a stall AOA tone.   

It needed the latter as the aircraft stalled 1 AOA unit prior to the buffet.  So if you pull to the buffet and relax just enough back pressure to not buffet, you were stalled.  This came out from the A-10 Paris Airshow crash.  If you watch the video, you can see the nose rotates upwards, but the flight path does not change.