Stall horn relay getting flaky

[Moonbat]

In a Mooney M20E, 1967, s/n 67008, the stall horn relay (in the port wing) is intermittent. I can liberally apply electronic cleaner (tuner) spray to it and exercise it enough to convince most folks that it is working, but... truth is, it bothers me. It works less well after sitting for a few days. It works better when I flip it up-and-down a zillion times as part of my pre-flight ritual. Does anyone have any idea where to find replacements for this relay? I've checked the obvious places (LASAR, Aircraft Spruce, Sporty's) with no luck so far. So I thought I'd ask here. 

[KB4]

Honeywell Micro Switch V3-2451-D8 is what I got off ebay.

[larryb]

Two things. Are you sure you don't mean "switch" when you say "relay." It is usually just a simple circuit of a switch and a sonalert. 

The Sonalert is the second thing. They often go bad, and may sound intermittent. A bad Sonalert could fool somebody into thinking the switch was bad. The Sonalert has 12v on one terminal, and the stall switch grounds the other terminal. To be sure, using a voltmeter check the voltage at the switch while exercising the switch. It should be 12v on the non-grounded terminal when the switch is open, and 0v when you activate the stall switch. If the switch checks out good the Sonalert is probably bad. Good thing they are cheap.

http://www.alliedelec.com/search/productdetail.aspx?SKU=70186814

[RobertGary1]

I believe they're just Mallory SonAlert. The stall is the short one that is steady. The gear is the tall one with the logic onboard to do the intermittent alert (so it doesn't sound like stall).

The stall horn switch in my Mooney is the same as the master caution in my boat.

-Robert

[carusoam]

The switch is an industrial switch...  that most likely isn’t wearing out...

Trying to maintain it properly... is a challenge because of where it is...

See if you can find a picture of what the whole part assembly looks like.

Spraying it randomly, might not get to where the dirt is...

pics are around here somewhere...

+1 on getting it to work properly...

Best regards,

-a-

[Guest]

14 hours ago, Moonbat said:

In a Mooney M20E, 1967, s/n 67008, the stall horn relay (in the port wing) is intermittent. I can liberally apply electronic cleaner (tuner) spray to it and exercise it enough to convince most folks that it is working, but... truth is, it bothers me. It works less well after sitting for a few days. It works better when I flip it up-and-down a zillion times as part of my pre-flight ritual. Does anyone have any idea where to find replacements for this relay? I've checked the obvious places (LASAR, Aircraft Spruce, Sporty's) with no luck so far. So I thought I'd ask here. 

Here is the wiring diagram for the airplane, the stall warning portion is the top right circuit.  You can simply ground the wire to the switch and see if the horn sounds.  If the horn is good and you have the standard switch it needs to go to Safe Flight Instruments in White Plain NY.  Very spendy to fix.

Ive never known anyone to find the actual switch part number.

Clarence

 

[Moonbat]

Thanks to all of you for helping me out on this issue. 

   Clarence - Did you mean "spendy" as in expensive, or was that a typo and you meant "speedy"? 

   Anthony - What does "+1 on getting it to work properly" mean?

[Yetti]

 

[Yetti]

 

[Andy95W]

Thanks, @Yetti, for doing the research and posting the old threads.

[Yetti]

3 hours ago, Andy95W said:

Thanks, @Yetti, for doing the research and posting the old threads.

my google fu is strong today

I believe someone was able to drill the rivets out of the big ole honeywell black box.   Found that there was a common microswitch in there.   Replaced it good as new.  For his tractor of course.

 

Edited December 11, 2019 by Yetti

[carusoam]

14 hours ago, Moonbat said:

Thanks to all of you for helping me out on this issue. 

   Clarence - Did you mean "spendy" as in expensive, or was that a typo and you meant "speedy"? 

   Anthony - What does "+1 on getting it to work properly" mean?

+1 ...  that’s me in agreement with somebody before....

Getting the stall warning system to work properly is the topic i was agreeing with...

 

my goofy stall horn warning system decided to go on vacation for a few months... without exactly telling me...

So I responded with going slower and slower trying to get the stall horn to sound during my landings...

 

Now, I’m sure to test the switch during the pre-flight, with the power actually on...   

This was years ago when I was still young-ish...

Sorry if I wasn’t clear enough...

Best regards,

-a-

[Guest]

22 hours ago, Moonbat said:

Thanks to all of you for helping me out on this issue. 

   Clarence - Did you mean "spendy" as in expensive, or was that a typo and you meant "speedy"? 

   Anthony - What does "+1 on getting it to work properly" mean?

Spendy, as in expensive to fix.  If you want it speedy, Safe Flight charges a “Spendy Speedy” fee of 20% more.

Clarence

[Moonbat]

First, a correction to the s/n of my plane - 670008 (not 67008). 

Second, I had a chance to get upside down under the panel before Christmas and test the Sonalert buzzer directly. It is NOT the problem. So, back to the original assumption that it is the switch in the wing. I found that I can reach my arm through the nearest inspection plate and get a hand on the culprit. I have sprayed contact cleaner liberally in that vicinity. I have exercised the stall vane every time I even pat the wings, so more often than I fly.

I think that last item had the most impact in making the stall warning 99%+ reliable. Of course there is that tiny, worrisome fraction of a percent to deal with... and that is where I leave this thread.