Where is your lift detector tab positioned in the opening in the wing?

[0TreeLemur]

Having difficulty adjusting my lift detector.   Despite the fact that it passes ground-test, it does not signal stall condition in the air.  Thinking it might be an internal issue.   I'm guessing that Mooney put that hole in the wing where it is for a reason.  This poll will help me confirm that most are installed in the middle and that adjustment should not be necessary.  Thx.

[MikeOH]

Hmm, I can't say for certain without looking at mine, but my 'visual memory' is that yours is pointing down way too much; might just be your camera angle.  I'll try and get out to the hangar today and take a couple of pictures of mine.

[EricJ]

Yours appears to be in the least sensitive (lowest airspeed) position, so moving it higher may make it start to trip.   It may take a few iterations to get it in a useful spot if it has been moved.

I marked mine before taking it out to rehab the switch, but it turns out that mine has very little adjustment room, anyway.   I wound up pushing it up as far as I could and it is still only just working reasonable well.

[0TreeLemur]

Thanks Eric. 

1 hour ago, EricJ said:

Yours appears to be in the least sensitive (lowest airspeed) position, so moving it higher may make it start to trip.

Thanks for the photo.  My switch is intermittent so it needs to refurbed.   The good news is I think the switch installed in my J is the one that was manufactured by Mooney to be serviceable.  It doesn't look like the FlightSafety version at all.

 

[A64Pilot]

Stall warnings are adjustable, often by moving the assembly up and down, sometimes by bending the vane. If yiu bend the vane make sure the switch still clicks when yiu move it.

As part of my production test flights I had to adjust them where they would go off 5 to 10 mph prior to stall in the landing configuration. A has been said moving them up increases the speed / decreases the angle of attack they will alert, down lowers it.

They are very commonly bent by people walking by and snagging it or a fuel hose etc.

If it works on the ground repeatedly, almost certainly it’s just out of adjustment or bent.

[MikeOH]

Here are photos of mine. It is an F so could be different.

 

[Fritz1]

My TKS stall warning would not go off when I bought the Bravo, Brian Kendrick test flew the airplane and we moved the entire stall warning assembly up by about 1/8", had to install new rivnuts, perfect thereafter, bottom line airplanes came out of the factory with stall warning in need of adjustment

[PT20J]

From my 1994 M20J

[carusoam]

Before attempting to bend the vane…

know that Mooney hardened it…

expect it to break before it bends…

 

also know that the vane pretty much marks where the split line occurs…

at high AOA… the split line descends the face of the leading edge…. 
 

when the air going above the wing, includes the vane in its path... the vane trips the switch and sounds the alarm…

The assembly has ordinary Honeywell micro switches in it…

getting to the assembly is quite a hassle…

 

ancient PP memories only… not a mechanic.

testing the stall indicator prior to flight became part of my usual check list after I went months without hearing a peep from it.

best regards,

-a-

[carusoam]

When comparing stall vane locations…

keep in mind we all fly the same wing…

but, the higher MGTW of the mid and long bodies… may show a different location of the vane…

the construction of the vane location definitely got a different mounting hole as aerodynamics became more importanter…

 

if you make a few flights while adjusting the vane location…

see if you can chart mm vs. Speed(alarm)

may need to bracket a couple of speeds…

 

Check the

maintenance manual to see if there is a procedure for this???

 

Best regards,

-a-

[0TreeLemur]

Comparing mine with the photo that Skip posted above, I don't see an obvious difference in terms of the location.   The vane on Skips (top) seems to be bent down a bit more than the vane on mine (bottom).  But the position on the wing seems quite similar.  I'm really starting to suspect that the problem with my stall warning is in the mechanism rather than its set point.  Like I wrote previously it does sound when I lift the vane during a ground check.   I does not sound when doing a stall aloft or in the landing flare.  

The S&MM does have an entry.  It is posted above.   I'm not at that stage yet- trying to determine if it is a setting error or an internal switch mechanism problem.  Plus the Phillips heads on the two adjustment screws on my bird are just about stripped.

 

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[carusoam]

45 minutes ago, Fritz1 said:

My TKS stall warning would not go off when I bought the Bravo, Brian Kendrick test flew the airplane and we moved the entire stall warning assembly up by about 1/8", had to install new rivnuts, perfect thereafter, bottom line airplanes came out of the factory with stall warning in need of adjustment

We have an interesting thread regarding the heated stall vanes…

around here somewhere…

this device becomes more important as ice changes the shape of the wing…. And the weight of the plane climbs into an unknown regime… where expected stall speeds may be higher than ever experienced before…

 

Go FIKI!

 

Best regards,

-a-

[carusoam]

6 minutes ago, 0TreeLemur said:

Comparing mine with the photo that Skip posted above, I don't see an obvious difference in terms of the location.   The vane on Skips (top) seems to be bent down a bit more than the vane on mine (bottom).  But the position on the wing seems quite similar.  I'm really starting to suspect that the problem with my stall warning is in the mechanism rather than its set point.  Like I wrote previously it does sound when I lift the vane during a ground check.   I does not sound when doing a stall aloft or in the landing flare.  

The S&MM does have an entry.  It is posted above.   I'm not at that stage yet- trying to determine if it is a setting error or an internal switch mechanism problem.  Plus the Phillips heads on the two adjustment screws on my bird are just about stripped.

I have seen pics of the stall vane and switch assembly around here before…

probably has part numbers of the switch itself included in the discussion…

and what was used to clean the switches.

 

having a spark plug hole camera will probably be helpful to determining the best route of action…

iirc… it’s a long way from the access panel to the leading edge area…

Best regards,

-a-

[Slick Nick]

On 2/10/2025 at 3:39 PM, A64Pilot said:

Stall warnings are adjustable, often by moving the assembly up and down, sometimes by bending the vane. If yiu bend the vane make sure the switch still clicks when yiu move it.

As part of my production test flights I had to adjust them where they would go off 5 to 10 mph prior to stall in the landing configuration. A has been said moving them up increases the speed / decreases the angle of attack they will alert, down lowers it.

They are very commonly bent by people walking by and snagging it or a fuel hose etc.

If it works on the ground repeatedly, almost certainly it’s just out of adjustment or bent.

Negative. NEVER bend ref vane on a mooney. It’s hardened steel and will snap. 

[Pinecone]

1 hour ago, Slick Nick said:

Negative. NEVER bend ref vane on a mooney. It’s hardened steel and will snap. 

So what do you do when they get bent by line guys leaning on them when they are fueling?

[Slick Nick]

10 hours ago, Pinecone said:

So what do you do when they get bent by line guys leaning on them when they are fueling?

They don't get bent. They're hardened steel. 

[Hank]

On 2/13/2025 at 3:30 PM, Slick Nick said:

Negative. NEVER bend ref vane on a mooney. It’s hardened steel and will snap. 

 

On 2/13/2025 at 4:41 PM, Pinecone said:

So what do you do when they get bent by line guys leaning on them when they are fueling?

 

13 hours ago, Slick Nick said:

They don't get bent. They're hardened steel. 

Stall warning vanes on lesser aircraft get bent accidentally. Mooney stall warning vanes are hardened to prevent this, and if you try to purposely bend it, it will resist right up until fracture. Because a bent stall warning vane is not accurate . . . .

[A64Pilot]

15 hours ago, Slick Nick said:

Negative. NEVER bend ref vane on a mooney. It’s hardened steel and will snap. 

I don’t think I said to bend it, but in fact many stall vanes out in the wild have been bent.

They don’t just go out of adjustment, either they have slid in their adjustment slots, or they have been bent. Sliding is more unlikely. One of the biggest culprits is a refueling hose, Ag planes its birds and trees. Most of the time when they get bent, they get bent down which means they don’t go off at all or do so late. 

Why did Mooney go to the trouble to harden the part? Because they get bent and they wanted to prevent that. I don’t think they hardened it myself, I think it’s SS and SS comes usually in 1/4, 1/2, 3/4 and full hard. I think they just picked my guess 3/4 hard maybe, or 1/2.

Now I’ve never done a production test flight for a Mooney, but every Thrush that I did the stall warning was a required check on EVERY aircraft, you recorded the airspeed the warning came on and the stall speed, warning had to be within 5-10 mph of stall on a Thrush. The FAA flight test pilot would spot check every so often and fly a production test flight randomly. I think it unlikely that Mooney let one out of the factory with the stall warning not correctly set, it’s just too simple a check and adjustment.

The way the stall warning works is pretty simple. In flight there is a specific point where the air impinging on the airfoils splits, above this point the air goes over the wing, below it the airflow goes under, increase the angle of attack and this point moves down, when the point goes under the stall warning vanes it goes from being pushed dow to being pushed up and the warning sounds. The tab is an angle of attack sensor.

Sheet of 301 1/2 hard I have, 1/2 hard is pretty darn hard.

 

Edited 23 hours ago by A64Pilot

[0TreeLemur]

Does anyone have reference P/N for the serviceable microswitch inside the Mooney spec. lift detector?  See photo I posted above.  I don't have the FlightSafety version installed in my a/c.

[EricJ]

3 hours ago, 0TreeLemur said:

Does anyone have reference P/N for the serviceable microswitch inside the Mooney spec. lift detector?  See photo I posted above.  I don't have the FlightSafety version installed in my a/c.

Is this it?

https://lasar.com/switches/stall-switch-v3-2451-d8

I don't know how Honeywell's part number system works, other than V3- is the basic pin-plunger microswitch, and the -D8 is for the 0.188" wide quick-connect (spade) terminals.

Otherwise it'd be fairly easy to try to find an equivalent or crossover just using the specs, but the -2451 doesn't appear in any of the documents that I can find.   If somebody could post a pic of the assembly with the switch part number showing that would be better to get it right.

The good news is that nearly all of the V3- and V7-, etc., microswitches are the same dimensions, so finding one with sufficient specs will fit and do the job.   It's not like it's carrying massive current or a big voltage or anything.  

I'd also add that sometimes when these get intermittent it's just the connections on the spade connectors.    Working them around a little or seating them better might be sufficient to getting it working again.

[PT20J]

According to onlinecomponents.com, the V3-2451D8 switch is discontinued and the recommended replacement is a V7-5F17D8

[Ricky_231]

Mine was doing the same thing: fine on the ground, but I took it up and stalled it all the way to the break and no warning. Adjusted it up (and tested, and adjusted some more), and now it's very close to the top. But I'm finally getting that chirp right before touchdown (the lack of which made me go check in the first place)

[Hank]

Well, ten or twelve years after posting my first landing video, I'm happy to say that my stall warning is still going off. This was coming home from Fayetteville, NC, about 3 hours' flight time. A little bumpy, but a good stall warning over the runway.

 

[PT20J]

Here's what it looks like:

[N201MKTurbo]

It lets you know it is still working.