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Gear troubleshooting - help with troubleshooting


Mark89114

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Will try and keep this clear but I tend to ramble.....

Replaced some nose steering parts due to wear, that required the nose gear to be removed, put it all back together and we had the plane on jacks so we were doing the testing for an annual.  Nothing looks mechanically wrong, in terms of binding, etc.

Gear ran up and down, did it several times and then the 4th time, gear only partially retracted.  Put gear switch to down and gear went down, all normal indications.  Tried it again, and it worked.  Tested the manual extension and it worked fine, reset everything, tested again, worked normally, thought we would try the electric again and it only came up halfway.  Would not cycle down with electric.  So used the manual system to extend. Reset everything and now won't even partially retract.  All of these operations on ground require us to use gear bypass button and the CB IS NOT popping on the gear actuation circuit, no CB's are popping.  The motor isn't getting warm, when it was working.

We have couple of theories, but it was like 100 degrees today so we quit.....

  1. Do CB's fail partially?  Damn near impossible to get behind the CB panel and test. 
  2. The gear relays are clicking like they are receiving a signal and we do have 24 volts on one of the pins when the gear is in up and the override button is pressed.  Thinking maybe the contactor is shot internally?  We have banged on them, but no luck with that technique.
  3. We briefly ran the motor directly, very carefully with an old battery, but it ran out of voltage before we could run it though a full cycle.  Maybe a bad spot on the armature?  

We have the wiring diagrams online, but they are about impossible to read.  Does anybody have a better easier to read version?    

Our current best guess is the relays are bad, but we are unsure why there are two?  Guessing one is for retract and the other for extension?  Again no wiring diagrams to trace it out.

Thank you,

Mark

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One oddity that occurs with heat...

The CBs are a temp sensitive, mechanical device, if they are getting warmer they will open as if a short circuit has occurred...

Of course the Breaker would pop out and require resetting...

 

The other oddity...  something is stopping the electricity from flowing, or not allowing the electricity to flow...

Relays are the only thing keeping electricity from flowing...

It would really help to know what relays are doing what... and what relay isn’t working...

 

PP thoughts only... anything sound inspiring?

Best regards,

-a-

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  • 3 weeks later...
On 8/17/2019 at 7:02 PM, Mark89114 said:

Will try and keep this clear but I tend to ramble.....

Replaced some nose steering parts due to wear, that required the nose gear to be removed, put it all back together and we had the plane on jacks so we were doing the testing for an annual.  Nothing looks mechanically wrong, in terms of binding, etc.

Gear ran up and down, did it several times and then the 4th time, gear only partially retracted.  Put gear switch to down and gear went down, all normal indications.  Tried it again, and it worked.  Tested the manual extension and it worked fine, reset everything, tested again, worked normally, thought we would try the electric again and it only came up halfway.  Would not cycle down with electric.  So used the manual system to extend. Reset everything and now won't even partially retract.  All of these operations on ground require us to use gear bypass button and the CB IS NOT popping on the gear actuation circuit, no CB's are popping.  The motor isn't getting warm, when it was working.

We have couple of theories, but it was like 100 degrees today so we quit.....

  1. Do CB's fail partially?  Damn near impossible to get behind the CB panel and test. 
  2. The gear relays are clicking like they are receiving a signal and we do have 24 volts on one of the pins when the gear is in up and the override button is pressed.  Thinking maybe the contactor is shot internally?  We have banged on them, but no luck with that technique.
  3. We briefly ran the motor directly, very carefully with an old battery, but it ran out of voltage before we could run it though a full cycle.  Maybe a bad spot on the armature?  

We have the wiring diagrams online, but they are about impossible to read.  Does anybody have a better easier to read version?    

Our current best guess is the relays are bad, but we are unsure why there are two?  Guessing one is for retract and the other for extension?  Again no wiring diagrams to trace it out.

Thank you,

Mark

Hi Mark, did you find the problem?

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On 8/17/2019 at 10:02 PM, Mark89114 said:

Will try and keep this clear but I tend to ramble.....

Replaced some nose steering parts due to wear, that required the nose gear to be removed, put it all back together and we had the plane on jacks so we were doing the testing for an annual.  Nothing looks mechanically wrong, in terms of binding, etc.

Gear ran up and down, did it several times and then the 4th time, gear only partially retracted.  Put gear switch to down and gear went down, all normal indications.  Tried it again, and it worked.  Tested the manual extension and it worked fine, reset everything, tested again, worked normally, thought we would try the electric again and it only came up halfway.  Would not cycle down with electric.  So used the manual system to extend. Reset everything and now won't even partially retract.  All of these operations on ground require us to use gear bypass button and the CB IS NOT popping on the gear actuation circuit, no CB's are popping.  The motor isn't getting warm, when it was working.

We have couple of theories, but it was like 100 degrees today so we quit.....

  1. Do CB's fail partially?  Damn near impossible to get behind the CB panel and test. 
  2. The gear relays are clicking like they are receiving a signal and we do have 24 volts on one of the pins when the gear is in up and the override button is pressed.  Thinking maybe the contactor is shot internally?  We have banged on them, but no luck with that technique.
  3. We briefly ran the motor directly, very carefully with an old battery, but it ran out of voltage before we could run it though a full cycle.  Maybe a bad spot on the armature?  

We have the wiring diagrams online, but they are about impossible to read.  Does anybody have a better easier to read version?    

Our current best guess is the relays are bad, but we are unsure why there are two?  Guessing one is for retract and the other for extension?  Again no wiring diagrams to trace it out.

Thank you,

Mark

Mark,

Relays and CBs rarely go bad, but I wouldn't rule them out 100%.  This sounds more along the lines of something didn't get properly reconnected and/or rigged after the gear work was done.

What parts were replaced specifically, who did the work for you, and did you have preloads checked/done before the airplane was returned to service?

Steve

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Since it is not tripping the CB you might also check the wiring and the airspeed switch.    Being able to use the bypass rules out the solenoids and much of the wiring.    Disconnecting the actuator will let the gear swing freely to check for binds.  But since it is stopping half way up unless something is bent or you missed something putting it back together it should be swinging freely.

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What does the gear indicator light show on the panel when it stops?  Does it show gear unsafe (in transit) when the motor stops?  If you are not getting a "Gear Unsafe" indication and not getting a tripped breaker, then I would venture a guess that you've got a limit swith that is acting up.  It is telling the system that the gear is up even if it's not. 

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Ok, as most people know electricity is a funny thing and some mechanics are good at it and some aren't.  We probably weren't as efficient as we should or could have been at diagnosing the problem summarized as gear not working......

We checked all switches, relays, etc.  For some reason we were not getting power to the main relay, power that runs the motor up and down, not control voltage...last thing we checked obviously, because it is a simple wire from the CB to the control relays and who would have suspected that?  The gear actuator power wire has 3 canon plugs from the CB to the actual relays.  One is hidden back behind the CB panel which would have made us cry if we had to get into that one or replace the CB as there is no free wire to move the panel out.  The other is the belly of the plane which is easy to get to and the third is in the lower sidewall.  Removed the side panel and all of the labels have since faded away......  We were able to trace the wires from belly up to the proper connector.  Removed the connector and the power pin was showing signs of wear and arcing.  Tested for voltage from CB, that checks, cleaned up the pin a bit and now we have voltage to the relays.  Put everything back together and all tested good.  For whatever reason that connector decided to fail when it was on the jacks after we did the nose wheel work.  I feel qualified to help diagnose other Mooney gear issues as I am familiar with it completely!!    

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