Stall Warning

[sreeves]

Does anyone have any guidance on how to adjust the stall warning switch on the wing for proper positioning? I have an "A" model and the stall warning switch has a vane that sticks out of the left wing leading edge. While on the ground, with the master switch on, if I move the vane up (it moves easily and fully) the stall warning horn sounds. In flight regardless of configuration, the horn won't sound even at full stall angle of attack. Seems like an adjustment. I don't want to try bending the vane thinking the switch may be adjustable in some way.

[Bruce Fenstermacher]

Good thing your A model does not require a stall warning!

Assuming your switch is installed as the 100 series service manual depicts, you loosen the 4 screws and slide the switch to adjust when it activates. BTW be nice to that switch. It is very very expensive to replace. I think upwards of $2000 was last reported. Reread my first sentence and be glad.

[sreeves]

Thanks for reminding me that the stall warning is not a required item on the 'A" model. $2,000!!!!! I have new respect for that switch, especially right where it is located now. I try to stall only intentionally anyway.

[sreeves]

See, another reason to leave mine alone!

[Ryan Smith]

Mine rarely, if ever comes on in flight. It tests fine on the ground, but it doesn't get enough pressure on it in the air. I took it out to try to clean it, and naturally, the case was riveted shut. No way to clean the contacts or blow bug guts out of it easily.

I've seen these on eBay go for $150. I think I would investigate that before giving Safe Flight that much money.

[ghostflyer]

I was about 500ft flying above a swamp and then the stall warning came on continuously . Quick check of the ASI , doing 95 kts . Straight and level I was . What a racket. I was about 30 mins from the nearest landing field . Looked out on the left wing to have a look and a great glob was near the stall warning . Landed and found a big grass hopper had impelled himself apron the vane . Cleaned the best I could but still sticky to move . On a maintenance day removed it and pulled it apart and cleaned it up . It took some time to adjust it back where it was a correct .yes, they cost a heap

[Bruce Fenstermacher]

From old memory from old posts it is the Cessna price that is nuts. Safe Lite did overhauls however at a 1/4 of the Cessna price.

[sfarringer]

Makes me appreciate my Ragwing even more!!!!!!

[sreeves]

Thanks guys. I think my switch works fine. It seems just like an adjustment. So maybe someday, when I'm completely bored, I'll carefully try to adjust it. Or not...

[170C]

Can't remember if this information has been posted previously or not. Is there a gauge (metal, plastic, cardboard) that provides the correct curvature of the pitot tube? Mine may be OK, but its not a smooth curve. Almost like it has previously been bent and then recurved but not as good as maybe it is supposed to be. Someone once told me they had something to check it.

[GAHorn]

I wrote about how to adjust the vane, and why it might test OK on the ground but not in-flight here:
http://www.cessna170.org/forums/viewtop ... ams#p74190

The micro-switch inside the vane unit looks like a microswitch commonly used in computers and other modern-day electronics...but it's NOT. It activates at a much lighter pressure than your finger-on-the-ground-test. I found this out when mine would not activate in flight but worked great on the ground. I believe someone takes these things apart when they discover the AMUs required by the mfr'r and decide to replace the microswitch. Since it tests on the ground...the airplane passes annual inspection by unknowlegeable A&P/AIs.

And that's a good thing... or not. REad the above link.

PS: Bruce, you're right and wrong on that matter of it not being req'd on an A-model.
You're right it doesn't have to be installed.
But if it's installed... it must work.

(Of course, you knew that. You were just helping relieve the stress level for Steve.)

So, Steve... you have a decision to make. Do you want it to work on the ground? or do you want it to work properly/as-intended... like the Friendly Aviation Admini-stress-ion wants it to?... or do you want to fly around with an odd, square hole in your left wing?