Cockpit Controls with Unknown Functions

Fat Albert is 1957 vintage. Different world back then.
I will dare anyone who is not a PA23 Apache pilot to get in and identify the function of various switches and breakers scattered about (unlabeled of course) and this includes at least two you will never even find while seated.
I do know what each one does and where to find the other two.

The original starter switch on a Tri-Pacer was another one where you had to be in the know.
 
BillTIZ said:
If you ended up with a broken wire somewhere in the bundle, they did not track it down and fix it, they just added a whole new wire the entire length from switch to what it controlled.
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Our gauge cluster at the top of the panel (fuel, oil, CHT) kept tripipng the breaker. Our A&P tested all the senders, no problem, tried to find the problem in the bundle from the breaker to the cluster, no go. Ran a new wire from breaker to cluster.
 
The switches that Cessna pilots often can't find or forget about are located on the doorposts. One operates the interior ceiling light, the other controls the little torpedo light mounted in the wing root.
 
flyingron said:
it was a joke "panic button" the previous owner installed.
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Heh... that brings back memories...

When I was a kid I had an uncle with a 172XP, he found a big red "panic button" with adhesive backing and stuck it on the panel. One day I was in the back seat when we were taking off with a full load including a couple non-flyers (plenty performance, plenty runway, cool day, no problems) and he had the power pulled back quite a bit and pulled it off the runway green, hung it on the prop in ground effect over the runway with the stall warning screaming, and started yelling "We ain't gonna make it, you lard asses!! We ain't gonna make it!" while punching that button for all he was worth.

That was a good airplane, it finally went to college with his kids. The engine went to Texas A&M and the rest went to Brigham Young.
 
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Jim Logajan said:
Could be its origin. It is now in a fixed gear 172. N1227U.
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Middle marker beacon light?

We have a very similar one in our 150. "Push to test" and "Dim" written on it as well.

qybn1t.jpg
 
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Here's a good one. We had a pilot go into an oral exam and was asked what the "stby comp" switch on the MD-11 did. Not knowing, the pilot responded that it was the stand by computer button. Of course he was asked about the stand by computer system, it's components, use, emergency procedures, the works. He quickly said that he didn't know and was quite upset because he was never trained on it.

The check airman started laughing and told the pilot that it turned on the light in the standby compass.
 
The last time I pushed a big red button (actually big red key) wondering what it did resulted in a rather impressive 4am response from the fire department outside. They were less than entertained.
 
A friend of mine who's watched Top Gun too many times has a dummy switch in the panel of his Grumman Tiger (AA-5B, not F11F) labeled "MSLS/GUNS". And I've seen several planes with something labeled "Panic Button."

That said, I've come across several cases where folks have switches about which they had no idea. The most common one seems to be a "DME 1/2" switch, which channels their DME to either the #1 or #2 nav receiver -- and in some cases remained in the panel after the DME was removed. Various switches related to aftermarket autopilots are also often a mystery to later owners. I've seen a lot of Grummans with an "Audio 1/2" switch, which selected between two audio amplifiers in the original 1970's factory configuration, usually long gone with the installation of an intercom, but the switch was still there -- and, of course, the person who bought that plane in 2005 has no idea what the story is. I've even found people with fuel injected engines who thought the lever labeled ALT AIR was their alternate static source selector, especially in planes where the real alternate static source valve was hidden under the panel.
 
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Dr. O said:
Fat Albert is 1957 vintage. Different world back then.
I will dare anyone who is not a PA23 Apache pilot to get in and identify the function of various switches and breakers scattered about (unlabeled of course) and this includes at least two you will never even find while seated.
I do know what each one does and where to find the other two.

The original starter switch on a Tri-Pacer was another one where you had to be in the know.
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Even the PA28s have the alternate bus switch hidden underneath the panel, along with the alternate static valve.
 
Ron Levy said:
I've even found people with fuel injected engines who thought the lever labeled ALT AIR was their alternate static source selector, especially in planes where the real alternate static source valve was hidden under the panel.
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+1, very common.
 
MAKG1 said:
Even the PA28s have the alternate bus switch hidden underneath the panel, along with the alternate static valve.
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That's where the parallel avionics master switch (for in case the primary one fails open in flight) is on my Tiger, along with some extra c/b's which wouldn't fit in the panel.
 
There are some levers on the floor next to the flap handle in various PA28s which are neither labeled nor described in the POH. Somebody opined that they were for sending heat or not to the back seat.
 
No mystery switches or controls, but an unmarked mystery 1/8 inch diameter socket just to the right and near the top of the engine gauge stack in my Tiger. It seems too old (tarnished) to be an input for a music player, and the intercom has its own separate music input.

I am curious as to its purpose, but not enough to pay someone to find out.
 
Ted DuPuis said:
I know what they all do and make a point of trying to remove ones that are extraneous. However, it's never ceased to amaze me when I'm flying in someone else's plane and ask "What's that do?" "I have no idea."
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comanchepilot said:
then you should not be flying the aircraft . . .
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Oh come on - If you haven't ever flown a plane that had a switch or button whose function you didn't know, you probably haven't flown very many. Old and new both have their foibles - There's one in the Mooney that I couldn't find any documentation for, and when I'd press it on the ground after starting up it didn't do anything. (It's red, it's labeled "ACR" and it's on the yoke next to the Ident button and the SEL/INFO switch.)

Since it clearly wasn't a flight-critical control (or it'd have been better documented), I didn't have a problem not knowing what it did. I also wasn't particularly comfortable hitting it in the air to experiment with what it did until I had more time in the plane.

So, eventually I hit it in the air. Turns out that it does have a purpose, and it still works. Points to the first person who guesses what it does... 'cuz Google doesn't even know.
 
Auto pilot cruise resume? Sets you back on the AP to where you were before disconnect?
 
flyingcheesehead said:
Oh come on - If you haven't ever flown a plane that had a switch or button whose function you didn't know, you probably haven't flown very many. Old and new both have their foibles - There's one in the Mooney that I couldn't find any documentation for, and when I'd press it on the ground after starting up it didn't do anything. (It's red, it's labeled "ACR" and it's on the yoke next to the Ident button and the SEL/INFO switch.)

Since it clearly wasn't a flight-critical control (or it'd have been better documented), I didn't have a problem not knowing what it did. I also wasn't particularly comfortable hitting it in the air to experiment with what it did until I had more time in the plane.

So, eventually I hit it in the air. Turns out that it does have a purpose, and it still works. Points to the first person who guesses what it does... 'cuz Google doesn't even know.
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I've seen buttons in that position that essentially just cut the autopilot off while it is depressed allowing you to make some quick manual change. Releasing it generally resumes the autopilot where it was before. No clue how that relates to the term ACR or if that's what your button does :)
 
I have a switch that I didn't know what it did until recently. More accurately, I knew what the previous owner told me it did, and accepted that...

The switch is on the far left side of the panel about midway up, a simple toggle switch. No label. When I bought it I asked what it did, the previous owner said it was an avionics master switch, but didn't work so they had a new one put in. This one is more centrally located between the yokes.

Right from the start, this didn't make much sense to me - if the switch is broken, why install a new one somewhere else and not just replace the existing one? But hey, whatever, I just didn't use it. I flipped it a few times while taxiing (with the "new" avionics switch on) and sure enough it didn't do anything. So I forgot about it for years.

Then, another pilot asked about it, and I tried it again, with the other avionics switch off. And the avionics came on! Switch the other one on, and they stay on.

So what I have is two avionics master switches, that both work, that are wired in parallel, so that as long as at least one of the switches is on, the avionics are on.

I have no idea whythey'd be installed this way. The original explanation didn't make much sense, and the current situation doesn't make much sense. I've thought about relabeling one of them humorously, but never got around to it.
 
RussR said:
I have a switch that I didn't know what it did until recently. More accurately, I knew what the previous owner told me it did, and accepted that...

The switch is on the far left side of the panel about midway up, a simple toggle switch. No label. When I bought it I asked what it did, the previous owner said it was an avionics master switch, but didn't work so they had a new one put in. This one is more centrally located between the yokes.

Right from the start, this didn't make much sense to me - if the switch is broken, why install a new one somewhere else and not just replace the existing one? But hey, whatever, I just didn't use it. I flipped it a few times while taxiing (with the "new" avionics switch on) and sure enough it didn't do anything. So I forgot about it for years.

Then, another pilot asked about it, and I tried it again, with the other avionics switch off. And the avionics came on! Switch the other one on, and they stay on.

So what I have is two avionics master switches, that both work, that are wired in parallel, so that as long as at least one of the switches is on, the avionics are on.

I have no idea whythey'd be installed this way. The original explanation didn't make much sense, and the current situation doesn't make much sense. I've thought about relabeling one of them humorously, but never got around to it.
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It is pretty useful if your single avionics master switch fails.
 
jesse said:
It is pretty useful if your single avionics master switch fails.
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Indeed. Having all your avionics go through a single switch creates a single point of failure for your whole panel. You'd want a high quality switch - or at least a parallel switch.
 
flyingcheesehead said:
Oh come on - If you haven't ever flown a plane that had a switch or button whose function you didn't know, you probably haven't flown very many. Old and new both have their foibles - There's one in the Mooney that I couldn't find any documentation for, and when I'd press it on the ground after starting up it didn't do anything. (It's red, it's labeled "ACR" and it's on the yoke next to the Ident button and the SEL/INFO switch.)

Since it clearly wasn't a flight-critical control (or it'd have been better documented), I didn't have a problem not knowing what it did. I also wasn't particularly comfortable hitting it in the air to experiment with what it did until I had more time in the plane.

So, eventually I hit it in the air. Turns out that it does have a purpose, and it still works. Points to the first person who guesses what it does... 'cuz Google doesn't even know.
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Map light?
 
bkspero said:
No mystery switches or controls, but an unmarked mystery 1/8 inch diameter socket just to the right and near the top of the engine gauge stack in my Tiger. It seems too old (tarnished) to be an input for a music player, and the intercom has its own separate music input.

I am curious as to its purpose, but not enough to pay someone to find out.
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Do you (or did you) have an earlier panel mounted GPS. I have seen some home-brewed connectors for GPs systems that had to be updated using a serial cable.
 
Henning said:
Should have told him "JATO pods".:D
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You do realize there is an STC for the Piper Aztec to hang a Aerojet General 15NS-250 rocket engine underneath it, correct? :yes:
 
Jeff K said:
You do realize there is an STC for the Piper Aztec to hang a Aerojet General 15NS-250 rocket engine underneath it, correct? :yes:
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Nope, but if I ever get an Aztec, be sure I'sd be looking to fit them.:yesnod:
 
Henning said:
Auto pilot cruise resume? Sets you back on the AP to where you were before disconnect?
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jesse said:
I've seen buttons in that position that essentially just cut the autopilot off while it is depressed allowing you to make some quick manual change. Releasing it generally resumes the autopilot where it was before. No clue how that relates to the term ACR or if that's what your button does :)
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Nope, that's a CWS (Control Wheel Steering) button - It lets you push it down, fly around by hand for a bit (great for showing pax a better view of something they just saw) and then when you let it go you're back on autopilot with the same modes and such as before.

There is one of those in the Mooney, but it's on the opposite side of the yoke from the ACR mystery switch.

teethdoc said:
Map light?
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Nope - I've got those under the yokes too, but they come on with and are controlled by the glareshield light control, located at the bottom of the panel just to the right of the radio stack...
 
flyingcheesehead said:
Oh come on - If you haven't ever flown a plane that had a switch or button whose function you didn't know, you probably haven't flown very many. Old and new both have their foibles - There's one in the Mooney that I couldn't find any documentation for, and when I'd press it on the ground after starting up it didn't do anything. (It's red, it's labeled "ACR" and it's on the yoke next to the Ident button and the SEL/INFO switch.)

Since it clearly wasn't a flight-critical control (or it'd have been better documented), I didn't have a problem not knowing what it did. I also wasn't particularly comfortable hitting it in the air to experiment with what it did until I had more time in the plane.

So, eventually I hit it in the air. Turns out that it does have a purpose, and it still works. Points to the first person who guesses what it does... 'cuz Google doesn't even know.
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Probably not, but AP disconnect?
 
I got a couple of good ones. My wife likes a lot of air on her. She feels better with a lot of fresh air blowing. The old Bo didn't have great venting with one large fresh vent low on the pilot side, and the exhaust up on the roof(smokers like it cause it sucks out). I checked the ops handbook which from 1948 is about 13 pages, and it says there is a vent, up on the firewall for added air that can be operated by the pilot or front pass toe(no, not kidding). So next time we hopped in, I took a flashlight, and sure enough, way up in the middle of the corner on the firewall is a rectangular door with a little toe extrusion sticking down. I had my wife sit in there and she couldn't reach it with the belt on.

So, off we go, into the sky and when we got up > 1000' I said ok, loosen your belt, and stick your toe under that latch, pull back to open the vent. She tried, and tried, and it wouldn't go. Finally, after about 5 minutes she jerked it open, and oh - my - god, I though the entire contents of the Suez canal had been lodged in that vent since the Nixon administration.

We had birds nests, we had cig butts, we had dirt, dust, crud and gunk come flying out that vent until she could get her foot on it, and close it. It took me 3-4 hours to clean all the crap out of the plane, and the open the vents and clean inside. What a mess.
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Back when I worked on dinosaurs in the computer biz, companies had huge computer rooms with mainframe water cooled computers in them. I was in First I-state Bank in downtown LA on a Friday afternoon about 3PM. We were investigating one disk adapter on one mainframe for a fault. The two guys I was with didn't know much about mainframes as they were techs that worked on the smaller servers and IO. So, one of the guys wants to go take a leak, and he heads for the exit door and swipes his badge on the reader, but it doesn't release. So, he tries again, then I hear him cuss a bit, and the next thing he does is hit the EPO for the room. Oh spit. Payday friday, and he just took down three running mainframes with one flick of his finger. The company wanted to fire all of us, but I advised them that this would be a mistake as I taught them the first thing once in the comp room was to touch NOTHING without asking. The other guy backed me up, and the button pusher got fired instantly. FIB was pretty unhappy for a while.
 
Threefingeredjack said:
I've often wondered why my footrests seem to move a little from time to time....:dunno: :D
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Must be flying a Piper or Beech?

I let my 6 year old daughter take the controls of the Baron a month ago. No adverse yaw in that plane at all...She was making perfectly coordinated turns and her feet couldn't even reach the pedals.
 
Fearless Tower said:
Must be flying a Piper or Beech?

I let my 6 year old daughter take the controls of the Baron a month ago. No adverse yaw in that plane at all...She was making perfectly coordinated turns and her feet couldn't even reach the pedals.
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Beech has an interconnect IIRC.
 
docmirror said:
Back when I worked on dinosaurs in the computer biz, companies had huge computer rooms with mainframe water cooled computers in them. I was in First I-state Bank in downtown LA on a Friday afternoon about 3PM. We were investigating one disk adapter on one mainframe for a fault. The two guys I was with didn't know much about mainframes as they were techs that worked on the smaller servers and IO. So, one of the guys wants to go take a leak, and he heads for the exit door and swipes his badge on the reader, but it doesn't release. So, he tries again, then I hear him cuss a bit, and the next thing he does is hit the EPO for the room. Oh spit. Payday friday, and he just took down three running mainframes with one flick of his finger. The company wanted to fire all of us, but I advised them that this would be a mistake as I taught them the first thing once in the comp room was to touch NOTHING without asking. The other guy backed me up, and the button pusher got fired instantly. FIB was pretty unhappy for a while.
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I was a 3rd party FE and worked on everything from 360s through 3090s, along with all the peripheral equipment. Most places learned pretty quickly to put a big plastic cover over the EPO and make sure it was prominently marked. I never was around when someone hit one, at least not unintentionally.
 
Still not exactly sure on how to use all the features of the GPS or autopilot. Is that bad?
 
MultiMediaWill said:
Still not exactly sure on how to use all the features of the GPS or autopilot. Is that bad?
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Are you instrument rated? If not then a lot of those GPS features don't apply to you.

I would dig through the pilot guides for the GPS and autopilot and see if there are any useful features you're not familiar with. I was never taught flight plan mode by my instructor, but I learned it on my own and it's very useful for indirect routes to avoid airspace or long stretches over water. I've also used it for sightseeing when I have multiple areas I want to fly over.
 
DaleB said:
I was a 3rd party FE and worked on everything from 360s through 3090s, along with all the peripheral equipment. Most places learned pretty quickly to put a big plastic cover over the EPO and make sure it was prominently marked. I never was around when someone hit one, at least not unintentionally.
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Yeah, I think we got that ball rolling for a lot of companies. I worked on the same spit for Sorbus after I got a package from IBM. Some good guys at Sorbus(Bell Atl services). I worked the 3800s & 3890s at FIB and in the valley for years. Made good $$$ and had a lot of fun. I also did my stint on the STK silos which were good for a lot of OT.

Maybe we crossed paths at some point? :)
 
docmirror said:
Yeah, I think we got that ball rolling for a lot of companies. I worked on the same spit for Sorbus after I got a package from IBM. Some good guys at Sorbus(Bell Atl services). I worked the 3800s & 3890s at FIB and in the valley for years. Made good $$$ and had a lot of fun. I also did my stint on the STK silos which were good for a lot of OT.

Maybe we crossed paths at some point? :)
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It's possible. I worked for Sorbus from the time I got out of the Army until some time in '88. I was a FPS in Cleveland, then Omaha. Generally took on all the stuff no one else wanted to work on. :) I left in '88 to work for a smaller local place (huge mistake, that was) then eventually started my own shop. When it was apparent that the bottom was dropping out of the third-party maintenance business, we morphed into an Internet service provider in '94/'95, and I morphed into a *NIX and network guy.

The silos and robotic magazines were the one thing I never did work on. I covered most stuff from the 1403 N1, 2311 and 2401 through the 3480, 3390 and some really weird stuff in between. I still have a 2821 bigh-speed buffer card and a 4341 paperweight.
 
DaleB said:
It's possible. I worked for Sorbus from the time I got out of the Army until some time in '88. ... and a 4341 paperweight.
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We must have met sometime. I was there from early 87-96. Oh and the 4341 WAS a paperweight. I watched the last of the dinosaurs get de-installed across the west. I was working the SCSI stuff for a while, then jumped to Sun and things went smoothly for a while.
 
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