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Electric trim switch -- source?



 
 
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  #11  
Old July 13th 07, 07:18 PM posted to rec.aviation.owning
Bob Noel
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Posts: 1,374
Default 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  
Old July 14th 07, 02:46 PM posted to rec.aviation.owning
Jay Honeck
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Posts: 3,573
Default 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  
Old July 18th 07, 08:50 AM posted to rec.aviation.owning
[email protected]
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Posts: 195
Default 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  
Old July 18th 07, 05:55 PM posted to rec.aviation.owning
Ray Andraka
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Posts: 267
Default 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  
Old July 19th 07, 12:59 AM posted to rec.aviation.owning
Kevin Clarke
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Posts: 147
Default 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  
Old July 19th 07, 01:03 AM posted to rec.aviation.owning
Kevin Clarke
external usenet poster
 
Posts: 147
Default 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  
Old July 19th 07, 04:11 PM posted to rec.aviation.owning
Jay Honeck
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Posts: 3,573
Default 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  
Old July 24th 07, 10:51 AM posted to rec.aviation.owning
[email protected]
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Posts: 195
Default 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  
Old July 31st 07, 06:07 PM posted to rec.aviation.owning
Ray Andraka
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Posts: 267
Default 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  
Old August 1st 07, 02:06 AM posted to rec.aviation.owning
Kevin Clarke
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Posts: 147
Default 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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