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Stall Warning Stuck On

Jeff_S

By Jeff_S
in General Mooney Talk

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Jeff_S Grand Master

Jeff_S

Posted
Posted

Hey all,

I did a quick search on this and didn't see anything directly related, but an interesting thing happened to me today on landing at PDK. I was flying through some cool light rain and it was pretty sloppy, so there was plenty of moisture around. At any rate, as we made a nice landing the stall warning horn came on like it usually does, only this time the darn thing wouldn't go off.  I was on the ground at home so I just taxied that way and got back into the hangar. But the vane isn't stuck, and I tried blowing out to see if any water had gotten in there and was maybe closing the circuit.  None of that mattered.

So is it possible that water would cause this? If not, what else would cause that circuit to stay closed? I did bump the vane a little bit while untying from my spot at Amelia Island, but it didn't bend out of shape and it didn't misbehave until we were landing in the rain.  Any ideas?

Thanks!

Marauder Grand Master

Marauder

Posted
Posted

I have seen rain cause this issue. If the vane is moving freely, it is most likely water in the switch. You can try opening the switch and gently blowing air to dry things out. The contact cleaner may also work. There are some with agents that are specifically designed to work for water displacement.

  • Like 1
Hank Grand Master

Hank

Posted
Posted

Mine wouldn't shut off after the mechanic washed it at annual last year. Belted in,mourned on master, heard stall horn. It quit when I pulled the breaker. By the next flight, it worked fine. I can see this happening in the rain, too. Just needs to dry out.

PMcClure Mentor

PMcClure

Posted
Posted

Jeff, mine has done this on occasion as well. Not necessarily only in rain. Haven't found a cause or solution yet. Tried cleaning the contacts, had the mechanic look at the vein. Does it sometimes but not very frequently. 

Jeff_S Grand Master

Jeff_S

Posted
  • Author
Posted

Given that others have had similar experiences, and the timing of my incident, I'm inclined to blame the rain as well. I only wish I had a circuit breaker I could pull, but I don't see one on my panel.  I'll test it again in a day or two to see if it's dried out, otherwise I'll look at the switch.  Thanks!

PMcClure Mentor

PMcClure

Posted
Posted
48 minutes ago, Jeff_S said:

Given that others have had similar experiences, and the timing of my incident, I'm inclined to blame the rain as well. I only wish I had a circuit breaker I could pull, but I don't see one on my panel.  I'll test it again in a day or two to see if it's dried out, otherwise I'll look at the switch.  Thanks!

I do have a circuit breaker and have pulled it to end the blaring on taxi. Once I found the vein stuck in the up position. Mechanic looked at it lubed it and returned to service, only to have it happen again on next flight (no rain). 

carqwik Experienced

carqwik

Posted
Posted

My "vane" got stuck once too....just as I was landing at Stockton CA for my annual....it was so annoying to taxi in all the way to Top Gun with that thing blaring!  Rain was not a factor...no idea what caused it by they fixed it at the annual.

 

carusoam Grand Master

carusoam

Posted
Posted

That can't be it...

'Never signals unless a stall is imminent...'

the one we have is the one that signals when raining, dirty, or out of adjustment.  It costs more to have these less than wonderful features.

The one I have goes into stealth mode, super quiet no matter how deep the stall.  Extra expensive...

more detail:  http://www.aircraftspruce.com/catalog/pdf/164sdraw.pdf

i was looking to see how the adjustment is made.  There are two long slots that match the screws in the pictures posted in another thread?

Best regards,

-a-

Marauder Grand Master

Marauder

Posted
Posted

 

We should be careful talking about these. There is someone on this site who will be doing midnight acquisitions from our planes and attempt to sell them back to us.

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Jeff_S Grand Master

Jeff_S

Posted
  • Author
Posted

So I think evaporation was the answer here. I went back out to get something at the hangar today, and the stall warning had ceased its incessant blaring.  Luckily I was at home when this happened. I would hate to think what that would be like to have it go off like that during a flight. Although I suppose that the force of air in-flight would probably keep it cleared out automatically...at least I hope!  I forgot to look at my circuit breakers to see if there is a specific one for that device, but it doesn't show up in the PDF of the POH I keep handy so I suspect there isn't one for these G1000 units.

carusoam Grand Master

carusoam

Posted
Posted

Figure 7-9 in the O's POH indicates that there is a stall warning CB.  Chapter seven is the systems section. Real basic wiring diagrams are in there.  The electronic version of these drawings are missing some of the finer detail that would make it worth copying and sharing here.  There are so many CBs it is a challenge to memorize them all.  The after market color coding devices are really helpful for the most important ones....

Best regards,

-a-

Marauder Grand Master

Marauder

Posted
Posted
So I think evaporation was the answer here. I went back out to get something at the hangar today, and the stall warning had ceased its incessant blaring.  Luckily I was at home when this happened. I would hate to think what that would be like to have it go off like that during a flight. Although I suppose that the force of air in-flight would probably keep it cleared out automatically...at least I hope!  I forgot to look at my circuit breakers to see if there is a specific one for that device, but it doesn't show up in the PDF of the POH I keep handy so I suspect there isn't one for these G1000 units.

Jeff -- there are lubricants that act as a moisture disperser that might prevent this in the future.

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Jeff_S Grand Master

Jeff_S

Posted
  • Author
Posted

Here's the circuit panel for an O2 GX from the PDF POH that I found online. This POH actually post-dates my true POH by a few months, but the panels should be the same. At least on this chart, there is no CB for the stall warning horn.

 

M20R O2 Circuit Panel.png

  • Like 1
carusoam Grand Master

carusoam

Posted
Posted

There are four empty spaces in that new drawing... And a music input at the bottom.

The Maintenace Manual would be the next place to look.  

Since the 90s, at least, the stall warning is an electronic tone.  It isn't the piezo buzzard of old.

It probably has been paired with the gear warning or annunciator panel to save weight, cost, or complexity.  I would think it was essential but it depends on how essential gets defined...

It definitely misses the ability to easily turn off a system that is fallible...

You may want to contact Stacy at the plant, or your MSC to get an answer if you don't have a MM.

Stacy's username here at MS is Sellis. (Stacy Ellis)

Best regards,

-a-

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