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#11
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Electric trim switch -- source?
In article . com,
Jay Honeck wrote: Anyone know where I can get my hands on a serviceable electric trim switch for my '74 Pathfinder? Mine's been erratic for years, but could usually be made to work properly with a shot or two of contact cleaner -- but no more. It still works fine in the "nose down" direction, but not at all in the "up" direction. Piper wants an absurd amount for this part, new. Anyone got an alternative? sounds like you need to troubleshoot your landing light circuit by replacing the switch... hint hint hint -- Bob Noel (goodness, please trim replies!!!) |
#12
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Electric trim switch -- source?
If the switch is the same as my Arrow II was it is actually just a bracket
that holds two individual Micro switches (thumb rocker depresses one for nose down, the other for nose up) that can be replaced with like switches from any source that carries them. Yep, it's a rocker that triggers two switches. The aft-most switch (the one that rolls the elevator up, to climb) is FUBAR. I suppose the thing could be dismantled, and the aft switch replaced -- but, man, that's some tiny work. Something for a jeweler to do, perhaps... -- Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination" |
#13
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Electric trim switch -- source?
Jay Honeck wrote:
John Kunkel wrote: If the switch is the same as my Arrow II was it is actually just a bracket that holds two individual Micro switches (thumb rocker depresses one for nose down, the other for nose up) that can be replaced with like switches from any source that carries them. Yep, it's a rocker that triggers two switches. Disclaimer: This is based on experience with ground vehicles and equipment. I don't have an A&P; I don't even have a TG&Y. Some of this may not be allowable owner maintenance. Some of this may not be allowable on a certificated aircraft. Your mileage may vary. "Micro Switch" is a trademark that's now owned by Honeywell (probably why John Kunkel capitalized it) but it gets used to refer to similar products from other companies, just like "Kleenex" or "Xerox" get used. Micro Switch is still around; Cherry is another well-known manufacturer. Many of the products are electrically and mechanically equivalent, but may not be legally equivalent in this situation. I suppose the thing could be dismantled, and the aft switch replaced I'm not sure, but there may also be issues with "rebuilding" or "repairing" the assembly (by replacing the one bad switch) vs. "replacing" the entire assembly. Again, not mechanical or electrical issues, but legal ones. -- but, man, that's some tiny work. Something for a jeweler to do, perhaps... I've never held one in my hand, but an operator control with switches "tiny enough to require a jeweler" and a 1974 anything (Piper, Cessna, Chevrolet, whatever) don't really go together in my mind. These switches come in a few standard body sizes and perhaps the most common is about 1.125" x 0.375 " x 0.625" (1 1/8 x 3/8 x 5/8, or even 30 mm x 10 mm x 15 mm). That size is all over the place inside pinball machines, vending machines, washers and dryers, etc. There is a smaller size that's only about 0.25" or 1/4" or 6 mm thick, which would start to get into the realm of "tiny" for me. There's a larger size that's about 2" or 50 mm long. There are N different options for actuator type - just the plastic switch plunger sticking out, a plain metal lever, a metal lever with a bent tip, a metal lever with a plastic roller, a metal plunger with a metal roller, etc. You can also get various levels of operating force (some of this depends on the lever and some of it on the spring inside the switch) and various contact ratings. The circuit is almost always single-pole, double-throw - three terminals, just like a three-way light switch for your house. Sometimes you will see a single-pole single-throw switch with just two terminals, like a "regular" light switch in your house. For the two-terminal kind, you have to know if you need the switch to be on when the lever is pushed, or on when the lever is *not* pushed. Mostly you only buy two-terminal switches if you're a manufacturer trying to save another nickel each on 100,000 units; if you're buying fewer switches than that, you buy the SPDT three-terminal kind, because they can almost always be used instead of (or as a replacement for) either type of two-terminal switch. Again, if you buy exactly the same part number as what's currently installed, from the same manufacturer, you don't have to think about most of this. If you get something different, it's on your head to determine that the new switch will do the same job as the old one. "The kid at Radio Shack Aerospace (or Bob at Bob's Pinball Machines and Aerospace) said it should work" probably isn't good enough, but you also probably don't need to pay $500 for a $3 switch either. If it's really a Micro Switch [tm] switch, http://www.mouser.com/catalog/630/1282.pdf may be of interest. They also carry Cherry switches. C&K may also make this kind of switch, but I don't think Mouser carries C&K. Disclaimer: This is based on experience with ground vehicles and equipment. I don't have an A&P; I don't even have a TG&Y. Some of this may not be allowable owner maintenance. Some of this may not be allowable on a certificated aircraft. Your mileage may vary. Disclaimer: I don't get money or other consideration from any companies mentioned. Matt Roberds |
#14
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Electric trim switch -- source?
Jay Honeck wrote:
If the switch is the same as my Arrow II was it is actually just a bracket that holds two individual Micro switches (thumb rocker depresses one for nose down, the other for nose up) that can be replaced with like switches from any source that carries them. Yep, it's a rocker that triggers two switches. The aft-most switch (the one that rolls the elevator up, to climb) is FUBAR. I suppose the thing could be dismantled, and the aft switch replaced -- but, man, that's some tiny work. Something for a jeweler to do, perhaps... -- Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination" Jay, The reason those are as scarce as hen's teeth is because they break. If the rocker and the superstructure that holds the rocker is in good shape, it may be repairable by replacing the microswitch if you can find the right switch. If not, you might be better off going to the later style switch made by Mason switch, which I think might be the "Seneca trim switch". Those are still pretty pricey, but at least you can find them. That would be easier as far as any approval goes because it is just retrofitting a part off the later model of the same airplane. Have you asked your avionics shop about it? They may have a lower cost alternative. The switch itself isn't anything special other than it is what Piper chose to put in the airplane. Any momentary contact, center off DPDT switch with similar current and voltage ratings to the original or the Mason switch would do, as long as you can get someone to sign off on it. |
#15
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Electric trim switch -- source?
Jay Honeck wrote:
Anyone know where I can get my hands on a serviceable electric trim switch for my '74 Pathfinder? Mine's been erratic for years, but could usually be made to work properly with a shot or two of contact cleaner -- but no more. It still works fine in the "nose down" direction, but not at all in the "up" direction. Piper wants an absurd amount for this part, new. Anyone got an alternative? I found one, of all places, on Ebay. I think I paid $120 for it. The part new is about $750 as I remember. The switch I got was for a Cherokee 6. I have a PA28-180 so it is a little different. The plane did have the rocker switch like yours Jay but now it is a slider switch. My A&P rigged something together to mount it. It looks nice and works great. The original owners learned to live with the broken switch. The top hat had fallen off, though the switch itself still worked so I knew it was fine electrically. Good luck, it is a real PITA. KC |
#16
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Electric trim switch -- source?
Jay Honeck wrote:
Anyone know where I can get my hands on a serviceable electric trim switch for my '74 Pathfinder? Mine's been erratic for years, but could usually be made to work properly with a shot or two of contact cleaner -- but no more. It still works fine in the "nose down" direction, but not at all in the "up" direction. Piper wants an absurd amount for this part, new. Anyone got an alternative? Thanks! These guys seem to have one too Jay, not sure on price. http://www.airpartsoflockhaven.com/c17.html google for piper trim switch. Lots of hits. KC |
#17
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Electric trim switch -- source?
-- but, man, that's some tiny work. Something for a jeweler to do,
perhaps... I've never held one in my hand, but an operator control with switches "tiny enough to require a jeweler" and a 1974 anything (Piper, Cessna, Chevrolet, whatever) don't really go together in my mind. These switches come in a few standard body sizes and perhaps the most common is about 1.125" x 0.375 " x 0.625" (1 1/8 x 3/8 x 5/8, or even 30 mm x 10 mm x 15 mm). That size is all over the place inside pinball machines, vending machines, washers and dryers, etc. There is a smaller size that's only about 0.25" or 1/4" or 6 mm thick, which would start to get into the realm of "tiny" for me. There's a larger size that's about 2" or 50 mm long. Well, the entire assembly fits nicely under your thumb, naturally. That assembly consists of the rocker, which actuates two switches -- one for "nose down" (in front) and one for "nose up" (in the back). If you imagine your thumb, that's probably an inch or so in size. The two switches and the rocker fit underneath that 1" -- so the switches themselves must be, say, 1/3" square? That's pretty small, by my reckoning. When I was trying to clean the contact, I had to take my glasses off and get my nose right in there, cuz it's invisible through my bi-focals... -- Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination" |
#18
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Electric trim switch -- source?
Jay Honeck wrote:
Matt Roberds wrote: I've never held one in my hand, but an operator control with switches "tiny enough to require a jeweler" and a 1974 anything (Piper, Cessna, Chevrolet, whatever) don't really go together in my mind. Well, the entire assembly fits nicely under your thumb, naturally. That assembly consists of the rocker, which actuates two switches -- one for "nose down" (in front) and one for "nose up" (in the back). If you imagine your thumb, that's probably an inch or so in size. The two switches and the rocker fit underneath that 1" -- so the switches themselves must be, say, 1/3" square? Ah. I was picturing something that mounted from behind the panel, so while the rocker (sticking through the panel) might fit under your thumb, the switches (behind the panel) could be larger than that. Also, I was figuring that you'd need something other than the tiny switches to get a decent contact rating - I was assuming that the motor(s) is (are) switched by the switches directly, not via a relay/contactor/solenoid or similar. If the switches don't have to carry and interrupt the entire motor current, then they can be pretty small, physically. There are some smaller standard-ish sizes. Mouser carries Cherry switches in "ultra-subminiature" (about 0.25 x 0.33 x 0.11 inches or 6.3 x 8 x 2.5 mm) and "sub-subminiature" (about 0.25 x 0.5 x 0.23 inches or 6.3 x 13 x 6 mm), which might be closer to what you have. At the moment, you're probably in one of the best places around to find either a replacement switch or someone that can fix yours. (Note: It is considered bad form to invite a fellow Pathfinder owner to one of your parties, get him or her drunk, extract the location where they are parked, and then sneak off to that location with a screwdriver while the owner is incapacitated. ) But if you can't come up with a complete switch, you might see if you can get and post the model number of the existing switches. Matt Roberds |
#19
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Electric trim switch -- source?
Kevin, If you still have the broken switch, Jay could probably use it as his has the top hat in good condition, but one of the microswitches is electrically bad. |
#20
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Electric trim switch -- source?
Ray Andraka wrote:
Kevin, If you still have the broken switch, Jay could probably use it as his has the top hat in good condition, but one of the microswitches is electrically bad. you're probably right, but alas, gone. KC |
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