I have a "Safe Flight Instrument Corp." stall warning horn/light. Sorry I can not supply the part number, my book is with the aircraft. Anyway,
the light still works, horn is dead. A new one was quoted at $657.
Is there a rebuild kit or someone that rebuilds them?
Stall warning horn/light
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
Stall Warning Horn
Those stall warning horns sure sound and look like those $10.00 radio shack buzzers - the 80 to 90dB ones.
stall horn not working
I had the same problem, and the logs showed it was a problem even back to '56. Verify that enough voltage is getting to the horn. I had a bad ground at the switch in the wing. Also, the automatic circuit breaker that powers the horn and the T&B can develop a lot of drop. My horn would work on the bench, but not in the plane. Clip a DVM to it in the panel, and make sure its getting its fair share of voltage. Low voltage will light the bulb, but not buzz the horn. But then the horns do crap out also...
Good luck.
-Glenn Hetchler
Santa Rosa, CA
'50A 5493C
Good luck.
-Glenn Hetchler
Santa Rosa, CA
'50A 5493C
Glenn
'50 170A N5493C
'50 170A N5493C
Glenn, ...You've nailed the hit right on the head. That is 99% of the problem with these things. The power to the unit is either low due to corrosion, etc, or the ground at the lift detector is bad. Very low current will illuminate the lamp yet not activate the horn.
There's one other, last-ditch, repair that I've done on these things.
If the bakelite case is opened (carefully) a small buzzer will be found inside. Across the terminals of that buzzer is an electrical condenser (such as can be purchased very inexpensively (59-cents) at Radio Shack).
Replacing that condenser has revived several of these stall warning horns, supplying me with a couple six-packs of German beer from grateful friends. I don't recall the exact specifications of the condenser, as the ones I used came out of a "grab-bag" of various components I purchased one time for a different project. But the exact specs didn't seem to matter very much either. I just picked one that was similarly sized.
Of course, ALL those buddys only fly experimental homebuilts, so I didn't have any qualms about legality.
There's one other, last-ditch, repair that I've done on these things.
If the bakelite case is opened (carefully) a small buzzer will be found inside. Across the terminals of that buzzer is an electrical condenser (such as can be purchased very inexpensively (59-cents) at Radio Shack).
Replacing that condenser has revived several of these stall warning horns, supplying me with a couple six-packs of German beer from grateful friends. I don't recall the exact specifications of the condenser, as the ones I used came out of a "grab-bag" of various components I purchased one time for a different project. But the exact specs didn't seem to matter very much either. I just picked one that was similarly sized.
Of course, ALL those buddys only fly experimental homebuilts, so I didn't have any qualms about legality.
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zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
Repalcement of the condensor in question with another is legal,as long as it sez FAA-PMA on it. Same with the horn,or any other minor parts. I have an official marker I stole from the local FSDO for labelling these types of parts,if you want to borrow it.
If you need to replace the horn itself,might I suggest that you adapt a unit from a whoopie cushion?
Eric
If you need to replace the horn itself,might I suggest that you adapt a unit from a whoopie cushion?
Eric
Ha, Eric!
You know what, tho'? It's sorta funny. One of the buddy's whose stall horn I fixed thusly is a real stickler about legality (being a lawyer) and always insists on avgas, no Marvel Mystery Oil, genuine Cessna parts, etc.
But he was completely satisfied with the little Radio Shack condenser repair when he found out that Cessna wanted $675 for that horn.
He's so happy that now he turns his battery master switch on during every pre-flight and goes out there to operate the lift detector and test the horn (something he used to never do). He says it gives him great pleasure every time he hears it now!
You know what, tho'? It's sorta funny. One of the buddy's whose stall horn I fixed thusly is a real stickler about legality (being a lawyer) and always insists on avgas, no Marvel Mystery Oil, genuine Cessna parts, etc.
But he was completely satisfied with the little Radio Shack condenser repair when he found out that Cessna wanted $675 for that horn.
He's so happy that now he turns his battery master switch on during every pre-flight and goes out there to operate the lift detector and test the horn (something he used to never do). He says it gives him great pleasure every time he hears it now!
It's required equipment on your B-model, Pete. Your IA mightn't want you to mention that publicly. 
(Sorta like my admission, huh?)
My own airplane had a bogus lift detector in it, although it took me a while to figure that out. On the ground it would test beautifully. I'd lift the little vane, the horn and light would operate just fine. I'd go fly, stall the thing and not a peep to be heard from it.
I took the lift detector out, put it on the workbench and put it through an endurance test. It never failed. It worked perfectly and reliably every time. I reinstalled it and test flew. I tried every stall imaginable including accelerated stalls and that damn thing would never operate!
I contacted Safe Flight up in New York. They would not sell me one directly, insisting instead that I go thru Cessna, etc. (Cessna wanted $600 just for that little switch!) I then found out that Safe Flight WILL overhaul one, however.
"Overhaul?", I said. Yep. They'd overhaul it for me for the sum of $352.
"Just what do you do to overhaul it...", I asked..."Remove the data tag, throw the switch into the trash, rivet the tag onto a new one and mail it back to me?" Basically,...yes. That's what they do. Except that the FAA makes them actually test for failure before they condemn the part to be replaced. Since it's such a simple device, the only thing to do is see if it works before tossing it. And, oh yeah, ...since it's being "overhauled" they will do it directly for the end-user. (And in the true spirit of "overhauls" ...they informed me it would be a 10-day to 3-week turnaround!
)
"What's to test other than move the lever?", I asked.
"Well...", they reply, "...we measure the force required to actuate the switch."
"What IS the specification for that force?", I inquired.
Turns out to be 1/2 gram. I grabbed my postal scale and went out to the hangar and found mine required almost 3 OUNCES! AHA!!
Removing the thing from the wing and looking a little closer I realize that the micro-switch looks newer than the rest of the device. It appears to have been borrowed from a throttle position switch or landing gear squat switch or something. I mean,...it's the correct size and design, ....but clearly it requires too much force to operate. It's not enough you'd notice on a preflight with your finger,...but that .5 gram spec and a postal scale sure showed it to require excessive effort to close that switch!
So I started researching and found that the same Safe Flight part number is used on the C-150 thru the 182 series. I started watching a certain website, and finally found one listed from a 180 in Canada offered by Upper Valley Aviation, complete with a serviceable tag up for bid....presently at $20. I waited until the last moment of the auction and bid $25 and won it.
When it arrived it not only had a yellow tag, it was also a heated unit! I haven't connected the heater element wires yet, but may if I ever install a heated pitot.
I tested it with the postal scale and it went off at 1/2 gram. Yeaaaay! I test flew it and it works perfectly!
Don't ask how much I paid for my spare warning horn/light unit. It'll just upset you.
(Sorta like my admission, huh?)My own airplane had a bogus lift detector in it, although it took me a while to figure that out. On the ground it would test beautifully. I'd lift the little vane, the horn and light would operate just fine. I'd go fly, stall the thing and not a peep to be heard from it.
I took the lift detector out, put it on the workbench and put it through an endurance test. It never failed. It worked perfectly and reliably every time. I reinstalled it and test flew. I tried every stall imaginable including accelerated stalls and that damn thing would never operate!
I contacted Safe Flight up in New York. They would not sell me one directly, insisting instead that I go thru Cessna, etc. (Cessna wanted $600 just for that little switch!) I then found out that Safe Flight WILL overhaul one, however.
"Overhaul?", I said. Yep. They'd overhaul it for me for the sum of $352.
"Just what do you do to overhaul it...", I asked..."Remove the data tag, throw the switch into the trash, rivet the tag onto a new one and mail it back to me?" Basically,...yes. That's what they do. Except that the FAA makes them actually test for failure before they condemn the part to be replaced. Since it's such a simple device, the only thing to do is see if it works before tossing it. And, oh yeah, ...since it's being "overhauled" they will do it directly for the end-user. (And in the true spirit of "overhauls" ...they informed me it would be a 10-day to 3-week turnaround!
)"What's to test other than move the lever?", I asked.
"Well...", they reply, "...we measure the force required to actuate the switch."
"What IS the specification for that force?", I inquired.
Turns out to be 1/2 gram. I grabbed my postal scale and went out to the hangar and found mine required almost 3 OUNCES! AHA!!
Removing the thing from the wing and looking a little closer I realize that the micro-switch looks newer than the rest of the device. It appears to have been borrowed from a throttle position switch or landing gear squat switch or something. I mean,...it's the correct size and design, ....but clearly it requires too much force to operate. It's not enough you'd notice on a preflight with your finger,...but that .5 gram spec and a postal scale sure showed it to require excessive effort to close that switch!
So I started researching and found that the same Safe Flight part number is used on the C-150 thru the 182 series. I started watching a certain website, and finally found one listed from a 180 in Canada offered by Upper Valley Aviation, complete with a serviceable tag up for bid....presently at $20. I waited until the last moment of the auction and bid $25 and won it.
When it arrived it not only had a yellow tag, it was also a heated unit! I haven't connected the heater element wires yet, but may if I ever install a heated pitot.
I tested it with the postal scale and it went off at 1/2 gram. Yeaaaay! I test flew it and it works perfectly!
Don't ask how much I paid for my spare warning horn/light unit. It'll just upset you.
Last edited by GAHorn on Thu Sep 08, 2005 3:09 am, edited 2 times in total.
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zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
I gotta go with Pete on this one. Got about 850 hours in my ragwing ,no stall horn.Today I was riding in the back seat of a friend's 180,4 people on board along with 60 plus gallons of gas. We went into a fairly short one-way strip,had to land downwind. When the stall warning buzzed,I thought it was a crash horn! Scared the crap outa me!
Another time a while back,I was flying a friend's 150 taildragger--in fact it was the guy who bought Pete's T-craft. Anyway,it didn't have any radio's or anything so we didn't have headsets on,not even earplugs. Never landed it before,so I was really concentrating on the approach. I was flaring into a real nice 3-pointer when the stall horn went off--I just about jumped right out of the airplane!
If it were me,I'd leave the horn part of the stall-warner broke!
Eric
Another time a while back,I was flying a friend's 150 taildragger--in fact it was the guy who bought Pete's T-craft. Anyway,it didn't have any radio's or anything so we didn't have headsets on,not even earplugs. Never landed it before,so I was really concentrating on the approach. I was flaring into a real nice 3-pointer when the stall horn went off--I just about jumped right out of the airplane!
If it were me,I'd leave the horn part of the stall-warner broke!
Eric
HOW DOES YURE SUKER WORK
ALL A YU FELLERS BETTER HOPE NOE FEDERALLES IS A READIN THIS FORUM.. FAKEY MIKRO SWITHCHES AN PHONY DATA TAGS IS A SURE WAY TO LEVENWURTH. WHATCHA ALL OURTA DO IS GIT SUMBODY TU INSTALL THE LATER MODEL CESSNA WHISSLE IN PLACE OF AN OVERPRICED PEACE OF LECTRICAL JUNK. THU ONLYEST PROBLEM IS BEEIN TALL ENUFF TO SUK AIR(*) AND LISSEN AT THE SAME TIME! SHORT FEMALE TYPES DOANT QUALIFY
*A NUTHER STORY BOUT HITE CHALLENGED STUDENT PILUTS, BUGS ONA LEEDING EDGE AND PREFLITE OF THE NON-LECTRIC STALL HORN LATER.
*A NUTHER STORY BOUT HITE CHALLENGED STUDENT PILUTS, BUGS ONA LEEDING EDGE AND PREFLITE OF THE NON-LECTRIC STALL HORN LATER.
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Dave Clark
- Posts: 894
- Joined: Mon Apr 22, 2002 6:25 pm
I'll be getting my stall horn working properly this winter. I got a great buy on a real nice used one. Then I'll put a dedicated circuit breaker on it that I can pull off and leave it that way! I'm with you Eric, it can be quite annoying, especially if you're inclined to land the plane properly.
Dave
N92CP ("Clark's Plane")
1953 C-180
N92CP ("Clark's Plane")
1953 C-180
Item 607, Stall Warning, in accordance with Cessna Dwg 0511062, is required equipment only on the 170 B-model. The earlier airplanes do not require it. This was due to improved (?) handling characteristics of the airplane with dihedral and lower stall speeds of the larger slotted flaps. The B-model would not display airframe "buffet" prior to stall, as required by the regs, so a stall warning became required equipment on that model.
If the later "whistle" type warning were installed, it would be necessary to obtain either a STC or Field approval, as it would be a change of the type certificate requirement of Item 607 per Cessna dwg 0511062.
If the later "whistle" type warning were installed, it would be necessary to obtain either a STC or Field approval, as it would be a change of the type certificate requirement of Item 607 per Cessna dwg 0511062.