Stall Warning Adjustment

[Bob Y]

If the stall switch is the same on the 9 as the 12, the stall vein operates a microswitch, which is adjustable via screws. To reduce the chance of moving the switch out of a ligament, I insert a thin metal strap - actually a piece of the banding material from one of the shipments - in the opening between the vein and the wing cutout on the side in which I want to bend the vein. If it does get out of alignment, you’ll have to remove the access panel below the stall warning vein, loosen the screws on the microswitch, readjust and retighten the screws. See KAI section 16, attached.

[Sportquattro]

Originally Posted by Bob Y

If the stall switch is the same on the 9 as the 12, the stall vein operates a microswitch, which is adjustable via screws. To reduce the chance of moving the switch out of a ligament, I insert a thin metal strap - actually a piece of the banding material from one of the shipments - in the opening between the vein and the wing cutout on the side in which I want to bend the vein. If it does get out of alignment, you’ll have to remove the access panel below the stall warning vein, loosen the screws on the microswitch, readjust and retighten the screws. See KAI section 16, attached.

Thanks Bob that sounds like a good method, I don’t suppose you’ve any knowledge of how much adjustment needed for a 5kt ish adjustment? I’m guessing a degree or two but any inside knowledge most welcome

[RandomSquawk]

My copy (rev 13, Oct 2020) has same typo.

Crazy coincidence that I happened to notice this same detail I wasn't even looking for, on the same day that someone else replied to a 12 year old thread.

[Bob Y]

Originally Posted by Sportquattro

Thanks Bob that sounds like a good method, I don’t suppose you’ve any knowledge of how much adjustment needed for a 5kt ish adjustment? I’m guessing a degree or two but any inside knowledge most welcome

No, sorry, it’s pretty much trial and error. On my first flight, mine was going off the 70 kts! Quite annoying.

[dcflyer84]

Had to replace my stall warning microswitch; obtained new one from Van's. Remounted the bracket in the exact same position. Flew. Warning came on too early; adjusted down per this thread. Multiple adjustments have been required, making very small bends. After this last adjustment, it starts going off at liftoff and stays on the entire flight. ??!?$%?*
Ideas from the collective?
I'm thinking the vane tab may have bent up/curved inside the wing, thus activating the switch arm too soon?

[NinerBikes]

Adjust tab UP to increase the speed the stall warning indicator comes on, ie at higher air speed = greater safety margin.


Adjust tab DOWN to lower the speed at which the stall speed indicator comes on, ie at lower air speed with less margin of safety between warning and stalling and possibly falling out of the sky= thinner safety margin.

[Bob Y]

Originally Posted by dcflyer84

I'm thinking the vane tab may have bent up/curved inside the wing, thus activating the switch arm too soon?

The method I described in post #11 works for me. Inserting something in the gap between the stall-warning vein and the edge of the wing cutout prevented the vein from bending inside the wing and keeps the bending force off the microswitch.

[dcflyer84]

I had reviewed the thread before I did anything the first time but thanks to those who clarified. Used a shim to hold the tab in place within the slot and adjusted again. Worked better; not going off the whole time anyway. Will keep tweaking.

[JwWright57]

You could (if you have not) install and calibrate the AOA system and then forget about the stall warning. Most would say its a lot better than the stall warning.