Down Limit Switch - Help

[moon_dog]

Hi all, apparently I have a bad down-limit switch in my M20F. The symptom is that the gear down light is intermittent and doesn’t come on right away when the gear goes down. Sometimes takes way too long to come on and is quite disconcerting in the pattern. 

Anyway, I need a replacement. The Lasar part is the Otto P6-24014. It’s almost a grand and is a special order item. 

Does anyone know of an alternative to this part? Or where I might be able to find a good used one?

Thanks in advance!

Edited April 11, 2023 by moon_dog

[carusoam]

wait…

You have electric gear….  
 

contact @Alan Fox

Or clean the switch…

Best regards,

-a-

[PT20J]

41 minutes ago, carusoam said:

wait…

You have electric gear….  
 

contact @Alan Fox

Or clean the switch…

Best regards,

-a-

According to the specs, it’s sealed.

[PT20J]

+1 for @Alan Fox

Search the part number online.

Call an Otto distributer.

Call other Mooney Service Centers

[LANCECASPER]

6 hours ago, moon_dog said:

Hi all, apparently I have a bad down-limit switch in my M20F. The symptom is that the gear down light is intermittent and doesn’t come on right away when the gear goes down. Sometimes takes way too long to come on and is quite disconcerting in the pattern. 

Anyway, I need a replacement. The Lasar part is the Otto P6-24014. It’s almost a grand and is a special order item. 

Does anyone know of an alternative to this part? Or where I might be able to find a good used one?

Thanks in advance!

https://peerlesselectronics.com/p6-14000-switch

They have 146 in stock.

[PT20J]

3 hours ago, LANCECASPER said:

https://peerlesselectronics.com/p6-14000-switch

They have 146 in stock.

That's not the same part number, though. Mooney used a P6-24014. 

Otto doesn't list the Mooney part in their current catalog. I would call them and see if there is a cross reference. https://www.otto-controls.com/-/media/products/electromechanical-switches/limitswitches/p6sealedlimitswitchesmilprf8805/p6-sealed-limit-switches-catalog-page.ashx

[moon_dog]

20 minutes ago, PT20J said:

That's not the same part number, though. Mooney used a P6-24014. 

Otto doesn't list the Mooney part in their current catalog. I would call them and see if there is a cross reference. https://www.otto-controls.com/-/media/products/electromechanical-switches/limitswitches/p6sealedlimitswitchesmilprf8805/p6-sealed-limit-switches-catalog-page.ashx

Correct. I called Otto this morning and the lead time for this item is 8-10 weeks...

Curious if a similar product is approved for use. 

Definitely ramping up the search for a used one.

[LANCECASPER]

1 hour ago, PT20J said:

That's not the same part number, though. Mooney used a P6-24014. 

Oops!  

[Ragsf15e]

You should call DMax and talk to him (Don Maxwell Mooney, Longview TX).  

I called and talked to him a few years ago and he gave me some specific part numbers.  I ended up lubing mine and (fingers crossed), it's been ok since.  However, I looked up the part numbers and they appear to be two components that actually make up the switch.  I'm not saying these are right - in fact they look different than yours, I'm saying you should call him, but I'm going to attach below so you can see...

I'm now curious because your limit switch looks much different than mine (1968 F).  What year is your F?  Mine look more like the ones Don told me about.  Maybe there is an alternate part you could use?  I'll attach a (crappy) picture of my limit switch - it's black and cube shaped, definitely different than yours.  Sorry about the picture, but it's in the bottom left.

MCD2711 - https://www.mouser.com/ProductDetail/Honeywell/MCD2711?qs=0x4sLrpp94KewLfSyp6k4A%3D%3D&gclid=CjwKCAjwitShBhA6EiwAq3RqA3nvmhMJynIznYPuCs0H7iLE9sKi8PtiUNmwOAOwZtTGgGje0yvq4hoC8iQQAvD_BwE

DT-2R-A7 - https://www.grainger.com/product/24A126?s_kwcid=AL!2966!3!606773749412!p!!g!!__EFKW__&gucid=N:N:PS:Paid:GGL:CSM-2296:AB578S:20500731&gclid=CjwKCAjwitShBhA6EiwAq3RqA9tu1iox7sux-IPLhsfy64P0hAF2rVytkY-OTvqT4M5_rR5B5o4AFhoCNh4QAvD_BwE&gclsrc=aw.ds

 

[moon_dog]

Turns out the Honeywell 1CH1-6 is also used in these airplanes and I was able to locate a used one at BAS. It's en route. We will see...

[Ragsf15e]

5 minutes ago, moon_dog said:

Turns out the Honeywell 1CH1-6 is also used in these airplanes and I was able to locate a used one at BAS. It's en route. We will see...

What year is your airplane?  The switch looks much different than my picture above?

[201Steve]

@moon_dog did you have luck with the 1ch1-6 as a down limit switch? The IPC calls out that part number as used for the gear squat switch (if so equipped). They appear identical to the 1ch116-6 which is the official down limit switch part number, but it seems some resellers call out the 1ch1-6 as a Mooney gear limit switch. 

[FLYFST]

On 4/11/2023 at 5:54 PM, moon_dog said:

Turns out the Honeywell 1CH1-6 is also used in these airplanes and I was able to locate a used one at BAS. It's en route. We will see...

Moon_Dog, I've had similar issues with my 1990 J model, and what worked out best was adjusting the switch stop (tab secured to the push-pull rod) so that it contacts the plunger face flat instead of at an angle.  My A&P previously tried lubing the plunger with CRC contact cleaner with immediate results that did not last much.  As a sealed switch, about the only place the lubricant could be of some effect is on the plunger, and that actually looked very good and corrosion free in my case.  My switch appears to have been replaced from the original and it is currently an Otto Controls P6-24014 alternate part number in the IPC.  When I called LASAR earlier this year looking for a Honeywell 1CH116-6 switch they told me that switch was no longer available, but recommended alternate part number P6-24014 (what I have now), and which in March 2024 was $1,152 new but out of stock.  They also suggested using another alternate part number 1EN1S priced at $1,768 and one was available then from the Mooney factory.

[201Steve]

@moon_dog did you have luck with the 1ch1-6 as a down limit switch? The IPC calls out that part number as used for the gear squat switch (if so equipped). They appear identical to the 1ch116-6 which is the official down limit switch part number, but it seems some resellers call out the 1ch1-6 as a Mooney gear limit switch. 
 

 

good feedback thanks! I just found the 1EN1S for a almost reasonable $460

[A64Pilot]

Ref cleaning switches, by all means do so as a temp measure, but be aware it’s almost always a temporary fix as most switches have some kind of plating on them and most of the time they get intermittent when this plating wears off and cleaning won’t of course replace the plating. Switches that trigger a relay so that they are only carrying a tiny amount of power last a very long time as opposed to those that carry significant amount of current due to arcing of the contacts.

Then all contact cleaners are not created equal, I’ve had the best luck with Deoxit, it’s not cheap but compared to the price of these switches it’s just pennie’s.

Ref are there any other approved switches? Download and read this AC ref parts substitution for antique aircraft, ALL Mooney’s are antique aircraft and this AC covers every Mooney ever made, in particular electrical parts are about the easiest to substitute, many if not nearly all are Standard Parts.

So look up Standard parts, I think if you could find a switch that would work and carry the amperage then yes it’s approved. I would quote this AC in the logbook entry though.

This AC has been out since 09, so 15 years? Not likely to change and surely every FAA inspector is aware of it.

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_23-27.pdf

On edit, I use contact cleaner as a troubleshooting measure, if the problem goes away when I clean a switch, then it’s likely that’s the problem so I try to find a switch.

Edited November 2 by A64Pilot