81 J gear relays

[A64Pilot]

My 81 J model has two gear relays of course, one up and one down. They are mounted in front of each other and are not marked that I can tell.

‘I need to replace the one that lowers the gear, which one is it, the one near the nose or the tail?

[A64Pilot]

No one knows which is which?

[mooniac15u]

The wires all seem to be labeled.  Have you looked at the electrical schematic for your serial number?

[A64Pilot]

No, I think I’ll shotgun it and replace both, but it would be nice to know, I’m not so good with schematics, some wires likely go to both etc.

‘If I had jacks, and I may before I get there, then of course I could find out which is which with a multimeter during a retract test, and I may.

‘I’m looking to see what it takes to hold down the tail. I’m 250 and it won’t go down with me, but I can bounce it so it’s close to 250, then of course add some for safety, and then add some more so that a person can climb in to the cockpit to actuate the gear, and I’d guess your at at least 400 lbs min. but likely 500 to be sure.

Concrete is 20 lbs per gallon, so I’d need a 25 gl wash basin min, and they aren’t easy to find believe it or not, probably best place would be a feed and seed.

‘So that takes me to an engine hoist, and they have no mechanical lock, or I don’t think they do.

‘I don’t have a clue what it takes to put an anchor point in the hanger floor, or who would you hire as I don’t have the tools?

[PT20J]

Schematic shows that the gear motor has a red wire and a black wire. Red wire goes to the down relay and the black wire goes to the up relay. Later models had a yellow wire instead of red, but the black always goes to the up relay.

[A64Pilot]

Outstanding, thanks, I remember seeing the red and black on the actuator, but I thought they spliced into aircraft wire, but I will look. If they do maybe I can get the wire number or buzz it out with the multimeter.

I still will likely replace both with the though that they are 41 years old and one is giving problems, how far behind could the other be. But if I can verify which is which I’ll label them for future needs.

I think the schematic indicates that they splice into numbered wires, but I can’t read the numbers

Edited May 7, 2021 by A64Pilot

[carusoam]

A64,

Don’t you rent a friend, or pay a kid, for something like this?

They throw the switch... while you observe where the electricity comes and goes?

Best regards,

-a-

[N201MKTurbo]

Those contractors are not made any more. There are replacements, but they are very expensive.

I had one fail and I was able to find a new old stock replacement. I think I got the last one. Good luck.

[A64Pilot]

8 hours ago, carusoam said:

A64,

Don’t you rent a friend, or pay a kid, for something like this?

They throw the switch... while you observe where the electricity comes and goes?

Best regards,

-a-

Need to be on jacks of course.

[mooniac15u]

14 hours ago, A64Pilot said:

Outstanding, thanks, I remember seeing the red and black on the actuator, but I thought they spliced into aircraft wire, but I will look. If they do maybe I can get the wire number or buzz it out with the multimeter.

I still will likely replace both with the though that they are 41 years old and one is giving problems, how far behind could the other be. But if I can verify which is which I’ll label them for future needs.

I think the schematic indicates that they splice into numbered wires, but I can’t read the numbers

I think you're right that they are spliced into numbered wires.  It might be easier to see the numbers in this version.

[A64Pilot]

1 hour ago, N201MKTurbo said:

Those contractors are not made any more. There are replacements, but they are very expensive.

I had one fail and I was able to find a new old stock replacement. I think I got the last one. Good luck.

Google the part number, you will come up with quite a few cross matches.

‘Most smart aircraft manufacturers assign their own part number to purchased parts. That makes them the sole source of supply, and makes it harder to find the part from other sources.

‘But the Relays are widely available, just not from Mooney, they are apparently commonly used on Golf Carts and winches, they are a 100 amp continuous duty relay.

‘Now I’m not abdicating using a relay not sourced from the aircraft manufacturer, but when said manufacturer won’t supply it, you have two choices, one of which is the junkyard, and that’s not legal either as the part won’t have an 8130.

‘Unless I’m mistaken the replacement requires a kit to adapt to it, and it’s not available either, I found several at junkyards and one NOS for $800.

The original relay can be had for about $20.

Edited May 7, 2021 by A64Pilot

[A64Pilot]

1 minute ago, mooniac15u said:

I think you're right that they are spliced into numbered wires.  It might be easier to see the numbers in this version.

It is,

thanks

[RJBrown]

Just an off the top of the head thought.

A how they work question. 
It appears to me that both relays are involved with both directions.

one relay is ground and the other relay is power. They trade jobs between up and down.

The picture schematic doesn’t show but are both relays normally closed to the ground contact and normally open to the power contact?

‘when UP is selected does the up solenoid move and the power points in the up relay are connected and ground goes through the DOWN relay.

Conversely when DOWN is selected the up relay is the ground and the solenoid in the down relay moves and the down contacts close providing power.

If my assumption is true a Down relay with bad ground points could keep the gear from going up.

to test this you would have to unhook the output wire (red or black) to check for ground.

Car electric windows are used this way and I’ve seen the NC contacts in the relay fail on the ground side. Made a weird result as power would alternately go where directed but the window still did not move because one side ground was lost.

 

[A64Pilot]

Way over my head as to why would both ground and power be switched on opposite relays, unless I’m mistaken and going only by the number of terminals, these relays are actually two pole as in they switch two circuits each. So it could switch both power and ground for one circuit, up for instance , or I guess could switch power and ground for opposite circuits, but in that case it would take both relays to operate correctly for either circuit to function, and I’m at a loss as to why that would be done, but I’m no real electrician, I sort of became that way because if your not, then you really can’t maintain more complex aircraft.

But I have pretty much decided to “shotgun” this and replace both relays anyway, original thought was why not replace a 41 year old relay, and or one quit, how far behind can the other be, but if your right, then I could be pulling my hair out if I don’t. Odds are I woud have replaced the down, still had the problem, jumped onto trying to procure a switch, changing that and still have the problem, just be poorer and confused.

[EricJ]

3 hours ago, A64Pilot said:

Way over my head as to why would both ground and power be switched on opposite relays, unless I’m mistaken and going only by the number of terminals, these relays are actually two pole as in they switch two circuits each. So it could switch both power and ground for one circuit, up for instance , or I guess could switch power and ground for opposite circuits, but in that case it would take both relays to operate correctly for either circuit to function, and I’m at a loss as to why that would be done, but I’m no real electrician, I sort of became that way because if your not, then you really can’t maintain more complex aircraft.

The gear goes up or down by reversing the polarity on the DC motor.    So to switch directions the A terminal gets switched from power to ground and the B terminal gets switched from ground to power, for example.   That's often done with two double-pole relays.

 

[Yetti]

Just to confuse things my 75 has only one relay.  So the switching is done with the limit switches which are click on click off.

It is the same one that is in an old ford tractor.   4 poles.   the 4th pole is for taking the brake of the back of the motor.   The brake on the motor holds the gear up and prevents chatter.

[KB4]

On 5/6/2021 at 5:21 PM, A64Pilot said:

‘So that takes me to an engine hoist, and they have no mechanical lock, or I don’t think they do.

Been discussed here before.  Just get right size for the ram.

https://smile.amazon.com/Climax-2C-050-Two-Piece-Clamping-Plating/dp/B001VXS9KS/ref=sr_1_34?dchild=1&keywords=clamshell+locking+collar&qid=1620579849&sr=8-34

Jack it up, install and tighten the collar so it sits 1/8" above bottom.  Take pressure off hoist and see if collar holds, if it does, jack back up and go to work.

[N201MKTurbo]

Here are the specs for the contactor:

It is wiring diagram 5 on the last page. It is Ametek SBD4201A

https://www.ametekswitch.com/-/media/ametekswitch/files/metal-case-solenoid.pdf?la=en&revision=5bef21bb-be76-45f3-adb1-d5d0872edfda

 

Edited May 9, 2021 by N201MKTurbo

[RJBrown]

Both relays are NC, normally closed in the ground position. Both sides of gear motor see ground. Only one relay moves to change gear position. If gear is down the up relay moves from ground to power and gear goes up. Limit switch turns off relay once up. While up both relays are again in the grounded position. To put gear down the down relay is activated and power now goes to the gear motor until turned off by down limit switch.

This description is from me based on automotive experience reading the above incomplete diagram. Is there an AP out there that can verify that this description is accurate.

 

[N201MKTurbo]

12 minutes ago, RJBrown said:

Both relays are NC, normally closed in the ground position. Both sides of gear motor see ground. Only one relay moves to change gear position. If gear is down the up relay moves from ground to power and gear goes up. Limit switch turns off relay once up. While up both relays are again in the grounded position. To put gear down the down relay is activated and power now goes to the gear motor until turned off by down limit switch.

This description is from me based on automotive experience reading the above incomplete diagram. Is there an AP out there that can verify that this description is accurate.

 

You are 100% correct.

FWIW

A spring pushes the disk against the top two big terminals connecting them together. When the solenoid is energized, by putting current to the two small terminals, it pulls the disk down and the top terminals are open and the bottom two terminals are connected.

Edited May 9, 2021 by N201MKTurbo

[Yetti]

21 hours ago, A64Pilot said:

Way over my head as to why would both ground and power be switched on opposite relays, unless I’m mistaken and going only by the number of terminals, these relays are actually two pole as in they switch two circuits each. So it could switch both power and ground for one circuit, up for instance , or I guess could switch power and ground for opposite circuits, but in that case it would take both relays to operate correctly for either circuit to function, and I’m at a loss as to why that would be done, but I’m no real electrician, I sort of became that way because if your not, then you really can’t maintain more complex aircraft.

But I have pretty much decided to “shotgun” this and replace both relays anyway, original thought was why not replace a 41 year old relay, and or one quit, how far behind can the other be, but if your right, then I could be pulling my hair out if I don’t. Odds are I woud have replaced the down, still had the problem, jumped onto trying to procure a switch, changing that and still have the problem, just be poorer and confused.

The answer is 4 bags of saccrete.   To hold down the tail.   The other answer is a Hilti nail gun and some concrete anchors with a plate.

[FlyingDude]

On 5/6/2021 at 5:21 PM, A64Pilot said:

Concrete is 20 lbs per gallon, so I’d need a 25 gl wash basin min

You don't really need that.

I built mine using a 60x60cm (about 2' x2') baseboard, which was sitting there. I installed 6 wheels rummaged from 2 $10 harbor freight dollies using 3" screws so that screws will be mostly in the cement. I made walls around the baseboard using lawn chute and profusely applied duct tape. Cut a hole in the center of the baseboard, passed the chain through that hole, then stuck an 80cm (2.5') iron rod through one of the rings of the chain and placed it across the diagonal under the baseboard. Pulled the chain up so that the iron is flush with the underside of the baseboard and then Stuck another piece of iron through the first ring above the baseboard, so that the chain won't fall through. Then mixed 4 bags of 80lb concrete directly in this "container". Added water sparingly so never puddles or loosened the duct tape. You need to make sure that the chain stays upright while the cement cures. Then trimmed the law chute plastic flush with the top of the cement. In this configuration, the chain actually acts on the iron rod which is under the baseboard which is in turn under the block of concrete. That way, if your concrete ever cracks, the chain will not slip up. 

I think 200lbs is good for an E. I built a bigger one in case my neighbors want to borrow it.

[1980Mooney]

On 5/7/2021 at 9:13 AM, A64Pilot said:

Google the part number, you will come up with quite a few cross matches.

‘Most smart aircraft manufacturers assign their own part number to purchased parts. That makes them the sole source of supply, and makes it harder to find the part from other sources.

‘But the Relays are widely available, just not from Mooney, they are apparently commonly used on Golf Carts and winches, they are a 100 amp continuous duty relay.

‘Now I’m not abdicating using a relay not sourced from the aircraft manufacturer, but when said manufacturer won’t supply it, you have two choices, one of which is the junkyard, and that’s not legal either as the part won’t have an 8130.

‘Unless I’m mistaken the replacement requires a kit to adapt to it, and it’s not available either, I found several at junkyards and one NOS for $800.

The original relay can be had for about $20.

 

12 hours ago, N201MKTurbo said:

Here are the specs for the contactor:

It is wiring diagram 5 on the last page. It is Ametek SBD4201A

https://www.ametekswitch.com/-/media/ametekswitch/files/metal-case-solenoid.pdf?la=en&revision=5bef21bb-be76-45f3-adb1-d5d0872edfda

 

Riddle me this Batman.....So if you install a pair of "golf cart" solenoids on the landing gear actuator of your J model and subsequently it has a gear up because the solenoids failed at the worst possible time, should your insurance pay or reject your claim?  Just wondering hypothetically...

Like I have said on other threads I hope you clearly log any "unique" solution that use golf cart or washing machine solenoids and get a Field 337 from your A&P.  It will save future owners and his/her A&P's a lot of time and grief when they are trying to sort out issues.

The solenoids on my J started acting up and sticking (sometimes up, sometimes down) about 19 years ago, one of the many times Mooney was in bankruptcy.  Parts were hard to come by then also.  The 14 V Gear Relay Retrofit Kit 940084-501, which modifies all 12 volt M20 C, D, E, F, G, J and K was either not available or crazy in price.  I got the drawings for the Retrofit Kit and bought the parts directly.  The Retrofit Kit uses Kissling Solenoids made in Germany and as I believe do all modern Mooney's.  The difference between those and your "golf cart" solenoid is that they are double coil, Military Grade, shock and vibration proof and waterproof to IP67 & IP6K9K (can withstand steam pressure cleaning).  These things are bulletproof.  I bought mine straight from Germany although Mouser here does distribute some Kissling relays.  The proper part is 26.72.03 and is still made.

KI-Relay26-50A-ds-a4-K1166683-en-2012.pdf (te.com)

All you need then is bracket 800375-1 (which you can probably fabricate), 2 Spike Suppressor Diodes 21EG11A and some nuts, bolts and rivets.

BTW - with all this talk and marketing that the new Mooney management is committed to supporting legacy aircraft, why isn't this available from the factory?  It fits all legacy 12V aircraft (which is a lot) and landing gear components are pretty damn critical.

 

 

[ArtVandelay]

If solenoids fail, you’ll be able to drop gear with emergency mechanism.

[1980Mooney]

16 minutes ago, ArtVandelay said:

If solenoids fail, you’ll be able to drop gear with emergency mechanism.

In theory.  That is why I said "at the worst possible time".  It doesn't always work.  Here is a recent gear-up due to failure of the emergency mechanism.  Another where it just doesn't work - and would be bad if he needed it.  If you are experiencing solenoid sticking and having to use the emergency mechanism repeatedly there is greater likelihood that you may one time damage the gears - which could render it useless during a future need.  There are other gear-ups based on user error of course where the pilot either forgot the emergency procedure or screwed it up.  Landing is high stress and non-routine failures only compound possible errors.  Who wants landing gear issues?

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