Gear problems, logic confusion help

[RobertGary1]

Recently when its cold I'm having problems retracting. I put the switch in the up position. The gear cycles up normally. But when it gets fully retracted the red "unsafe" light stays on and at that moment the gear horn starts going off. The "fix" is to fully retract and then bring it back up. 

1) Obviously this isn't the squat switch since the gear does come up

2) It can't be the throttle switch since that wouldn't set the red unsafe light (and the "fix") doesn't change the throttle position

3) It can't be the down limit switch because the green light comes on at the right time and if it was stuck in the "down position" I assume the gear would think its down the moment it came off the up limit switch.

4) The up limit switch may make sense but then how does it know to sound the gear alarm at the exact moment the gear is fully up? Also wouldn't the motor just keep running until it pops the breaker?

 

 

-Robert

[MikeOH]

You need to pull the schematics for your exact S/N as the system varied a bit over the years.  However, I believe the up/down limit switches have TWO sets of contacts: one set associated with running the motor, and the other set controls the gear warning/alarm system.  Hence, you could have an indication problem even if the motor is behaving properly.

[PT20J]

I believe @MikeOH is correct. I'd put it on jacks and remove the belly panels and see what's gong on.

[MikeOH]

From the Mooney Maintenance Manual, 106, Rev D, 8/1/81:

The gear warning system schematics are on pages 9-101 through 9-103.

The gear motor system schematics are on pages 9-66 through 9-71.

[Hank]

5 hours ago, RobertGary1 said:

Recently when its cold I'm having problems retracting. I put the switch in the up position. The gear cycles up normally. But when it gets fully retracted the red "unsafe" light stays on and at that moment the gear horn starts going off. The "fix" is to fully retract and then bring it back up. 

1) Obviously this isn't the squat switch since the gear does come up

2) It can't be the throttle switch since that wouldn't set the red unsafe light (and the "fix") doesn't change the throttle position

3) It can't be the down limit switch because the green light comes on at the right time and if it was stuck in the "down position" I assume the gear would think its down the moment it came off the up limit switch.

4) The up limit switch may make sense but then how does it know to sound the gear alarm at the exact moment the gear is fully up? Also wouldn't the motor just keep running until it pops the breaker?

 

 

-Robert

My C did this intermittently, then in winter did it every flight, sometimes not stopping when lowering the gear. New pucks cured it. Turned out I still had the original pucks, approx. 43 years old. The last eleven years have been blissfully silent when raising the gear, regardless of outside temperature. 

[Ragsf15e]

2 hours ago, Hank said:

My C did this intermittently, then in winter did it every flight, sometimes not stopping when lowering the gear. New pucks cured it. Turned out I still had the original pucks, approx. 43 years old. The last eleven years have been blissfully silent when raising the gear, regardless of outside temperature. 

The pucks only affect those few years with the squat switch and if the gear move up, it shouldn’t be the squat switch.  However, it’s complicated enough that anything is possible.  It’s best to work on replicating it on jacks.

[RobertGary1]

1 hour ago, Ragsf15e said:

The pucks only affect those few years with the squat switch and if the gear move up, it shouldn’t be the squat switch.  However, it’s complicated enough that anything is possible.  It’s best to work on replicating it on jacks.

Im starting to wonder if the squat switch could somehow get into ground mode after the gear comes up. My shock discs are older. 

[AIREMATT]

When it’s cold (not sure where you are or what cold is), but in MN the pucks don’t expand and things in the gear don’t expand when the gear comes up. Causes many funny oddities to happen at that point. Maybe the switch’s need to have pressure from expanding pucks to keep switches closed.

Maybe a warmer day or warming the plane in a heated hangar for a few hours and trying it would help troubleshoot that possibility.

[Ragsf15e]

11 hours ago, RobertGary1 said:

Im starting to wonder if the squat switch could somehow get into ground mode after the gear comes up. My shock discs are older. 

Wouldn’t surprise me if the squat switches can go bad like that and cause issues, but I think it’s unlikely that your discs are causing that when the gear is up.

[Yetti]

On 2/26/2023 at 12:56 PM, RobertGary1 said:

Recently when its cold I'm having problems retracting. I put the switch in the up position. The gear cycles up normally. But when it gets fully retracted the red "unsafe" light stays on and at that moment the gear horn starts going off. The "fix" is to fully retract and then bring it back up. 

1) Obviously this isn't the squat switch since the gear does come up

2) It can't be the throttle switch since that wouldn't set the red unsafe light (and the "fix") doesn't change the throttle position

3) It can't be the down limit switch because the green light comes on at the right time and if it was stuck in the "down position" I assume the gear would think its down the moment it came off the up limit switch.

4) The up limit switch may make sense but then how does it know to sound the gear alarm at the exact moment the gear is fully up? Also wouldn't the motor just keep running until it pops the breaker?

 

 

-Robert

More information needed.   First sentence.  Are you saying the red light stays on when the green gear safe light comes on.   Second sentence I think you mean "extend".   I would start with contact cleaner on the micro switches and exorcise fully.    I believe the red light is powered by the Solenoid(s).   When it is making it contact, the red light is powered.

 

[MikeOH]

1 hour ago, Yetti said:

   I would start with contact cleaner on the micro switches and exorcise fully.

Don’t you need a priest and holy water for that?

[Yetti]

16 minutes ago, MikeOH said:

Don’t you need a priest and holy water for that?

It helps to get the gremlins out.

[N201MKTurbo]

I think your down limit switch isn't fully opening. I would clean/lube it real good. Put the plane on jacks with the wheels up, spray the switch shaft with lube and work it in and out a bunch of times, wipe it off and repeat a few times.

One thing to try is stomping on the floor if it does it, see if that makes it stop. The switch is right below your seat and mounted to the floor, if it is stuck, stomping on the floor will jar it loose.

[MikeOH]

53 minutes ago, Yetti said:

It helps to get the gremlins out.

Yeah, the devil’s in the details 

[RobertGary1]

10 hours ago, N201MKTurbo said:

I think your down limit switch isn't fully opening. I would clean/lube it real good. Put the plane on jacks with the wheels up, spray the switch shaft with lube and work it in and out a bunch of times, wipe it off and repeat a few times.

One thing to try is stomping on the floor if it does it, see if that makes it stop. The switch is right below your seat and mounted to the floor, if it is stuck, stomping on the floor will jar it loose.

It does seem to know exactly when it’s done and the green light comes on at the right time when it reaches full down 

[Ragsf15e]

8 hours ago, RobertGary1 said:

It does seem to know exactly when it’s done and the green light comes on at the right time when it reaches full down 

It gets confusing down there though because there’s both uplimit and down limit switches.  If one is sticking, you can have some weird stuff that’s difficult to sort out.  
When I had this type of issue a couple years ago (no squat switch on mine though) I called dmax and he got on the phone with me.  Basically told me, step 1, do what @N201MKTurbo said, lube those switches.  Step 2, here’s the part numbers for them.  Step 3, bring it to him.  It stopped happening after step 1 but I have no idea if I exorcised something with lube like @Yetti recommended?

[Yetti]

On 3/2/2023 at 1:59 AM, RobertGary1 said:

It does seem to know exactly when it’s done and the green light comes on at the right time when it reaches full down 

So does green light come on while the red light is on in it's error state?

From the 75 F schematics.    The red light is controlled by the up limit switch. 

It is the up limit switch that has 3 wires coming into it.

down stream further is the Gear Relay (mine only has one)  Some have two relays

downstream of that is the Gear Actuator.

There is a lot going on with this one circuit also has the floor light for the manual window and the gear warning horn.

I would still start with the easy stuff of lubing the gear.   contact cleaner on the switch.   Clean up all the other stuff under there.

[ilovecornfields]

On 3/1/2023 at 1:50 PM, N201MKTurbo said:

One thing to try is stomping on the floor if it does it, see if that makes it stop.

My son must have attended the same A&P school that you went to. 

[N201MKTurbo]

2 hours ago, ilovecornfields said:

My son must have attended the same A&P school that you went to. 

Who went to A&P school? I just took the test.

[N201MKTurbo]

2 hours ago, ilovecornfields said:

My son must have attended the same A&P school that you went to. 

It's like the old TVs, when the horizontal hold is out, do you whack it on the side or the top? I keep getting confused...

[Yetti]

1 hour ago, N201MKTurbo said:

It's like the old TVs, when the horizontal hold is out, do you whack it on the side or the top? I keep getting confused...

There is actually some science behind this.   To put myself through college I did two way radio work.   The radios were in the cabs of mixer trucks in Humidston.   So we had the hard hat fix.   Take your hard hat and wack the radio.   It worked because the edge connectors would move and make contact again.   Same reason first step in fixing aircraft com stuff is to rerack it several times.    Reracking the boards also worked on IBM mainframes.

[N201MKTurbo]

2 hours ago, Yetti said:

There is actually some science behind this.   To put myself through college I did two way radio work.   The radios were in the cabs of mixer trucks in Humidston.   So we had the hard hat fix.   Take your hard hat and wack the radio.   It worked because the edge connectors would move and make contact again.   Same reason first step in fixing aircraft com stuff is to rerack it several times.    Reracking the boards also worked on IBM mainframes.

I remember those days, I was P1-11-52650 10-18-82 I wrote that on so many F&D certs when I worked for the RCC and the County.

[RobertGary1]

8 hours ago, Yetti said:

So does green light come on while the red light is on in it's error state?

From the 75 F schematics.    The red light is controlled by the up limit switch. 

It is the up limit switch that has 3 wires coming into it.

down stream further is the Gear Relay (mine only has one)  Some have two relays

downstream of that is the Gear Actuator.

There is a lot going on with this one circuit also has the floor light for the manual window and the gear warning horn.

I would still start with the easy stuff of lubing the gear.   contact cleaner on the switch.   Clean up all the other stuff under there.

When gear comes full down green light comes on and red light goes off. When gear comes up once it gets to the full up position the gear warning horn starts blaring and the red light stays on. 

[PT20J]

16 hours ago, RobertGary1 said:

When gear comes full down green light comes on and red light goes off. When gear comes up once it gets to the full up position the gear warning horn starts blaring and the red light stays on. 

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).

 

[RobertGary1]

1 minute 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).

 

Yea that’s what’s happening. The squat switch somehow triggers once the gear is up and I get the sonalert. My donuts are very warn so I bought new ones. Will see how that works