81 J gear relays

[1980Mooney]

Edited May 12, 2021 by 1980Mooney

[1980Mooney]

The relay is “26.72.03”. Open the link:
https://www.te.com/content/dam/te-com/documents/industrial-and-commercial-transportation/global/kissling-documents-data-sheets/Data_Sheets_Documents_Kissling/contractors/KI-Relay26-50A-ds-a4-K1166683-en-2012.pdf

[1980Mooney]

The Kissling relay comes with the spike suppression diode already installed.  So that is redundant on the parts list. 

Yes Mooney originally designed golf cart solenoids into their planes but sometime in the 90’s they shifted to Mil Grade solenoids on all planes. 

The Kissling relays are dual coil, Mil Grade, waterproof and survive steam cleaning. They will probably last the remaining life of the Mooney without an issue. Higher performance (more reliable) at a higher price point. The cross-reference golf cart relays at a much lower price point (either authentic Ametek or Chinese knockoff) will probably work reliably but maybe not as long depending on each plane’s environment.  That may or may not be important to every owner. I know the BPM “golf cart  “ solenoids originally spec’d by Mooney on my plane failed at 20 years.  

Edited May 12, 2021 by 1980Mooney

[N201MKTurbo]

One of my golf cart relays only made it 40 years, the other one is still going. 
 

Pure junk...

[A64Pilot]

The Kissling relay is a better relay, I doubt anyone could make a logical argument that it isn’t, and price isn’t an issue not really.

However what’s the basis of approval for putting them on my older aircraft? The fact that they are used on newer aircraft won’t get you there unfortunately.

If the relay ends up being the problem, my golf cart relay lasted 41 years, almost positive what make it quit is corrosion of the contacts as they are a 100 amp relay, I doubt arcing from 15 amps or less did it. The Kissling is a hermetically sealed relay and should prevent it from getting internal corrosion, could last well longer than me certainly, but then if the golf cart relays go for 40 years, that’s longer than I have left and likely longer than the aircraft.

I had an epiphany the other day, I won’t need to put a 30 year roof on the house when it needs one in 5 years or so.

‘I picked the Kissling for Thrush specifically because they could survive being pressure washed as an Ag plane lives in a highly corrosive environment and a good operator de skins and washes his aircraft daily, same reason I went with the Ancor heat shrink and hot glue lined wire splices.

‘I can defend using an identical cross matched part that meets the form, fit and function when the part called for is no longer available, but using a completely different part of a different design that is a different fit and form factor would be tough. 

Edited May 12, 2021 by A64Pilot

[A64Pilot]

I just had a thought.

‘I believe at some point Mooney went from a 14V electrical system to a 28V?

Is your newer airplane that uses the Kissling relays a 28V airplane? Mine is a 14V.

I ask as the 26.72.03 part number you gave appears to be a 24/28V relay

Edited May 12, 2021 by A64Pilot

[PT20J]

Here are the part numbers for my 28V. Gear relays are RL5.

Mooney generally identifies vendor part numbers for COTS parts. The exceptions I’ve found are when a COTS part is part of a Mooney next higher assembly and only that assy part number is procurable from Mooney. An example is the control surface attach bearings which come pressed into the brackets from Mooney. The other exception is when Mooney has a standard part customized. An example is the circuit breaker switches which have custom legends.

 

[A64Pilot]

If anyone is interested, pic is of the old and new relay 12V. The new one appears to be about 1/8” longer but I don’t see that being an issue.

Edited May 12, 2021 by A64Pilot

[dooleypster]

I had a similar issue with my 89 J.  Called Mooney, they said they don't make the individual relays anymore.  Called Dan at Lasar.  Had to buy a new combined unit of both up and down relays (aftermarket).  Very expensive!  Replaced the old units with the new and never had an issue again.  Ordered the part from Lasar which was drop shipped from Mooney.

[1980Mooney]

2 hours ago, A64Pilot said:

I just had a thought.

‘I believe at some point Mooney went from a 14V electrical system to a 28V?

Is your newer airplane that uses the Kissling relays a 28V airplane? Mine is a 14V.

I ask as the 26.72.03 part number you gave appears to be a 24/28V relay

You are correct.  26.72.03 is 28V and 26.72.23 is the 12V version

Edited May 12, 2021 by 1980Mooney

[EricJ]

3 hours ago, A64Pilot said:

‘I can defend using an identical cross matched part that meets the form, fit and function when the part called for is no longer available, but using a completely different part of a different design that is a different fit and form factor would be tough. 

That's generally consistent with my reading of the ACs that have been written on the topic, although I think one might even be able to make the case that deviating in form factor may not be an issue if all of the relevant functional specs are "at least as good" as the original if a more highly compatible part is not reasonably available.

 

[A64Pilot]

I agree, but if you can meet all three, then you should in my opinion.

[A64Pilot]

Update on the intermittent gear extension problem, the new relays work or at least they do so far,

But I don’t think that was my issue, both old relays bench test perfectly, you can cycle them many times and they always work, and there is always continuity on the poles.

When removing the second relay I found this, when the terminal fell off of the wire on removal, several things are wrong with this picture, first it’s the wrong size terminal, secondly it wasn’t crimped with the correct tool and as they all look identical I can only assume it’s been that way for 41 years, but the wire being loose was I believe my issue, not an actual intermittent relay. I may replace the others at Annual just to be sure, or at least do the redneck mechanic pull test.

‘This terminal was on one of the small posts that actuate the solenoid

Edited May 14, 2021 by A64Pilot

[carusoam]

Great follow-up A64, with pic!

Best regards,

-a-

[A64Pilot]

Yeah, but it’s still not fixed, it did it again the other day.

I’m now going to limit switches, I have a can of de-oxit and bought an engine hoist yesterday. I plan on borrowing a neighbors wing jacks if they will fit.

‘I figure it’s the down limit switch as if I understand the system it’s the switch that needs to be closed for the gear to come down, but it appears to be a sealed switch, the up limit switch is a standard looking micro switch.

 

[A64Pilot]

OK, aircraft on jacks so I can retract and clean limit switches.

Sprayed the contact cleaner and actioned the switches, ran the gear up and down several times and it seemed fixed, then it failed, then failed again. I found that I could wiggle the cockpit switch and it would start going down, did that more than once so now I think it is indeed the cockpit switch.

Sprayed the deoxit in the switch and actioned it with the battery off. 

‘Since then I have run the gear up and down probably a dozen times and no failures, not knowing if there is a duty cycle I let it sit for thirty minutes or so after about three cycles.

[carusoam]

There isn’t a cooling off period for the gear motor that I am aware of...

We have two different gear ratios for the gear...

The fast one is known to have some challenges in the past...

Many got swapped for the slow one...

On the ground, things may not cool as quickly, as it does when flying...

PP thoughts only, not a mechanic...

Best regards,

-a-

[A64Pilot]

I’m not aware of a duty cycle either, just figured to be conservative.

‘How do you know which gears you have? cycle time?

I have an 81 J with an Avionic actuator, I’ll attach a pic. Can the gearing be determined by serial or part number?

You can see on the data plate the duty cycle is intermittent, but I don’t know how often or how long defines intermittent, so I gave it a short rest between cycles

Edited May 21, 2021 by A64Pilot

[1980Mooney]

14 hours ago, carusoam said:

There isn’t a cooling off period for the gear motor that I am aware of...

We have two different gear ratios for the gear...

The fast one is known to have some challenges in the past...

Many got swapped for the slow one...

On the ground, things may not cool as quickly, as it does when flying...

PP thoughts only, not a mechanic...

Best regards,

-a-

The Service Bulletin M20-279 for the Avionics Actuator/Motor says:

"Allow @ 1 minute between cycles to avoid overheating motor"

See instruction 7

SBM20-279C.pdf

[carusoam]

Great pic A64...

The rating on the label never made sense to me... for our application...

Sure is stout...

I was looking for the gear ratios

We have two different ones...

A search around here should reveal... a fast one and a slow one...

Something like 20:1 and 40:1...

Best regards,

-a-

 

[A64Pilot]

20 hours ago, 1980Mooney said:

The Service Bulletin M20-279 for the Avionics Actuator/Motor says:

"Allow @ 1 minute between cycles to avoid overheating motor"

See instruction 7

SBM20-279C.pdf 188.2 kB · 6 downloads

Thank you.

[A64Pilot]

7 hours ago, carusoam said:

Great pic A64...

The rating on the label never made sense to me... for our application...

Sure is stout...

I was looking for the gear ratios

We have two different ones...

A search around here should reveal... a fast one and a slow one...

Something like 20:1 and 40:1...

Best regards,

-a-

 

Yes, it seems to be way de-rated, which I like, derating is often a way to a long life.

Data plate says it’s good for 2000 lbs and 55 amps, It’s protected by a 15 amp breaker and mine seems to pull about 10 or 12 or so looking at the amp meter.

I’m aware of the different gear ratios but am unaware of what I have. Gear cycle time seems quick but not really fast, I’d guess maybe 5 sec, but that’s a guess only, probably less.

 

I took it out this morning and did several approaches and go-arounds, didn’t touch as I live on a grass field, it’s not rough, but it’s not smooth like pavement either.

Go arounds are dead easy, just full throttle, get the gear and when you get the flaps, be running the trim nose down, the flaps and trim seem to wash each other out so there is no excessive pitch force.

Anyway it hasn’t hesitated dropping gear yet, still early to declare victory, but I think it is the gear switch. I’ll feel better in a month.

[A64Pilot]

The rating I think only applies to maintenance, the manual if I remember correctly has you retracting and extending 5 times to check for proper operation and interference etc.

Who cycles the gear over and over in flight?

[ArtVandelay]

The rating I think only applies to maintenance, the manual if I remember correctly has you retracting and extending 5 times to check for proper operation and interference etc. Who cycles the gear over and over in flight?

 

Have you ever had the back (clutch) spring replaced?

 

 

Notice the maintenance sticker.

[A64Pilot]

I just got the airplane and I’m pretty sure nothing has ever been done to the gear actuator included. 2200 TT

Been contemplating best course of action, searching back some it seems quite a few are determined that only a few years have bad springs in that they were formed after heat treat and that of course starts a crack, Don’t have any idea as to the validity of that.

‘I don’t think I want to do it myself, but do I take the aircraft to someone in Fl, or do I remove and send the actuator to Lazar or someone else?

Are springs even available? I’ve not yet been able to buy a single Mooney part, relays, limit switches, gear switch, all are unavailable.