Gear problems, logic confusion help

[Yetti]

1 hour ago, PT20J said:

The warning light will illuminate whenever neither the gear up nor gear down limit switches are closed.

The warning horn will activate when the squat switch is closed and the gear switch is in the up position. Power will be removed from the gear motor in this case.

So, if somehow the squat switch closed during retraction before the up limit was reached, the light would be on (because the up limit switch had not activated), the gear would stop retracting, and the horn would be on (because the gear selector is in the up position and the squat switch is closed).

 

The squat switch is wired to the down limit switch.   This is an error with the retract, not the extend.

The horn and the red light are part of the same up limit circuit.

 

Believe focusing on the up limit switch is where the issue will be.

 

 

[RobertGary1]

44 minutes ago, Yetti said:

The squat switch is wired to the down limit switch.   This is an error with the retract, not the extend.

The horn and the red light are part of the same up limit circuit.

 

Believe focusing on the up limit switch is where the issue will be.

 

 

Im thinking my worn donuts allow so much slop the squat switch is triggering when up. Otherwise the gear seems to know when it’s up and the motor stops. 

[Hank]

34 minutes ago, RobertGary1 said:

Im thinking my worn donuts allow so much slop the squat switch is triggering when up. Otherwise the gear seems to know when it’s up and the motor stops. 

That was my experience. New donuts fixed it, improved taxiing and softened my landings!

[PT20J]

1 hour ago, Yetti said:

The squat switch is wired to the down limit switch.   This is an error with the retract, not the extend.

The horn and the red light are part of the same up limit circuit.

 

Believe focusing on the up limit switch is where the issue will be.

 

 

This description does not appear to agree with the schematic. Power for the gear up relay runs through the gear switch, the squat switch and the UP limit switch. So power can be interrupted to the motor by any of those switches. The horn and light are not the same logic because the horn can sound when the gear unsafe light is off, and the gear unsafe light can illuminate when the horn is silent, or they can both be on, or off, at the same time depending on the condition.

[Ragsf15e]

25 minutes ago, PT20J said:

This description does not appear to agree with the schematic. Power for the gear up relay runs through the gear switch, the squat switch and the UP limit switch. So power can be interrupted to the motor by any of those switches. The horn and light are not the same logic because the horn can sound when the gear unsafe light is off, and the gear unsafe light can illuminate when the horn is silent, or they can both be on, or off, at the same time depending on the condition.

I love how the gear logic evolved over time too… my ‘68 has the red “unsafe” light on when the gear is completely up. And that’s how it was designed to work. Freaked my brother out when he saw it (he’s a usaf pilot too), “what’s wrong with the gear?!” If both my red and green are on or off, then there could be trouble.

I guess my point for you guys troubleshooting this is to make sure you have the exact right schematic.  Which you probably do…

[N201MKTurbo]

If you can follow a Mooney schematic with absolute certainty, more power to you. My eyes keep skipping lines and I have to trace them out 5 or 6 times till I’m fairly certain that I have it figured out.

[PT20J]

49 minutes ago, Ragsf15e said:

I love how the gear logic evolved over time too… my ‘68 has the red “unsafe” light on when the gear is completely up. And that’s how it was designed to work. Freaked my brother out when he saw it (he’s a usaf pilot too), “what’s wrong with the gear?!” If both my red and green are on or off, then there could be trouble.

I guess my point for you guys troubleshooting this is to make sure you have the exact right schematic.  Which you probably do…

Excellent point. It's always frustrating when people post a question and we cannot tell whether it's an A or an M or what year. There were more than a few changes over the years.

In this case, the OP's N-number looks to be a 1976 M20F. I don't have a schematic for that but I used a schematic for a 1977 M20J which is likely the same.

[PT20J]

4 minutes ago, N201MKTurbo said:

If you can follow a Mooney schematic with absolute certainty, more power to you. My eyes keep skipping lines and I have to trace them out 5 or 6 times till I’m fairly certain that I have it figured out.

The trick is to get close and match up the wire numbers from each end  I redrew the gear part for my 1994 M20J so I could figure it out because it's the most complicated circuit and it's hard to follow those connections all over the page.

[Fly Boomer]

10 minutes ago, PT20J said:

Excellent point. It's always frustrating when people post a question and we cannot tell whether it's an A or an M or what year. There were more than a few changes over the years.

In this case, the OP's N-number looks to be a 1976 M20F. I don't have a schematic for that but I used a schematic for a 1977 M20J which is likely the same.

I don't know about those models but, for the M20K, there are several schematics.  You have to know the serial number of the airplane to get the correct one.  And even then, I have seen some inconsistencies in serial number assignment.

[RobertGary1]

2 hours ago, Yetti said:

The squat switch is wired to the down limit switch.   This is an error with the retract, not the extend.

The horn and the red light are part of the same up limit circuit.

 

Believe focusing on the up limit switch is where the issue will be.

 

 

I find that since I was one of the last F’s I’m usually a better match for the J schematics than the F’s. People usually assume I’m a J anyway since they’d started putting J stuff on the last F’s on the line. 

[Yetti]

On 3/4/2023 at 8:00 PM, RobertGary1 said:

I find that since I was one of the last F’s I’m usually a better match for the J schematics than the F’s. People usually assume I’m a J anyway since they’d started putting J stuff on the last F’s on the line. 

The schematics I am looking at cover through F model  22-1272

The key tell will be if you have 1 gear solenoid or two

[Jess-lopez]

Hey there Robert. Did you figure out what was causing your gear issue?  I'm having the same identical problem on my 77 M20J. Thanks 

Edited November 25, 2023 by Jess-lopez
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