Gear Problem

[Releew]

While taking off the gear relay circuit breaker tripped and gear light remained in the Unsafe Position.  The Red light (Gear Unsafe)was illuminated and the view port was crosshatched.  Tried to reset the breaker and it popped twice.  Leveled off and kept the aircraft in the white arc.  I manually extended the gear until the Gear Safe light was illuminated.  It took six pulls which indicates the gear was most likely about half way in its retract cycle.

Going back to place the airplane on jacks and drop the belly to stat to look.  Does anyone have any suggestions on troubleshooting?  Any guidance would be appropriated.

 

Thanks!

 

Rick

[kortopates]

If its something mechanical, good chance it'll be obvious. Be sure to look at gear door linkages for in case something broke  allowing a door to become disconnected and prevent gear from coming up (assuming you have inner gear doors). Hopefully no bent retraction tubes. 

Edited August 6, 2019 by kortopates

[Ragsf15e]

Check and make sure the breaker is still good.  Simple test with voltmeter.  They wear out, build resistance and heat up.  Normally won’t reset until cooling down if they are hot.  Any idea how old the breaker is?

[Hank]

The left nose wheel door arm broke on mine, helpfully pointed out by the lineman while parking. Flew home gear down, called A&P on Monday, ordered new one from Lasar.

The shiny new part: 

[Releew]

Just inspected all mechanical linkages and could not find anything obviously wrong.  In the belly, there are two relays and two limit switches.  I am assuming the relays are for Up and Down and the limits are definitely for gear down and fully retracted.  Anywhere in between shows Gear Unsafe. 

All wires are tight to the terminals and there is nothing loose.  The only other switch in the system I think is the gear up/down on the panel.  I know there is the gear bypass switch and I think a flow switch that senses airspeed above 60 knots as a permissive to raise the gear.

If anyone had a schematic I would appreciate it very much.

92 M20J MSE

Thanks!  Rick

[carusoam]

Check the #1 reason for this issue...  the emergency gear system gets accidentally unlatched.  Then it gets in the way of the usual gear operation...

Often happens with back seat passengers getting in and out... they don’t know what they have stepped on.

Use caution, in this case, a brass part can get accidentally modified to be unusable...

PP thoughts only, not a mechanic...

Best regards,

-a-

[Yetti]

When was all of the gear lubed last?   Hint new grease can be spotted. When was the actuator lubed last?  Do not send the motor to California to get worked on.

[Releew]

All gear components were recently lubed.  I am leaning towards the switch on the panel.  Going to pull the glare shield ASAP.  

I did check the top hat latch cover and it was secure.  This was the second flight of the day when this occurred.  I am certain it was secure because I had to disengage it to manually extend the gear to the safe position.

 

Thanks!  Rick

 

[kortopates]

20 hours ago, Releew said:

Just inspected all mechanical linkages and could not find anything obviously wrong.  In the belly, there are two relays and two limit switches.  I am assuming the relays are for Up and Down and the limits are definitely for gear down and fully retracted.  Anywhere in between shows Gear Unsafe. 

All wires are tight to the terminals and there is nothing loose.  The only other switch in the system I think is the gear up/down on the panel.  I know there is the gear bypass switch and I think a flow switch that senses airspeed above 60 knots as a permissive to raise the gear.

If anyone had a schematic I would appreciate it very much.

92 M20J MSE

Thanks!  Rick

The schematic is included with the service manual along with a troubleshooting guide. They're available from your MSC. 

One of the reasons why the breaker pops is that the gear motors is locked. Besides having the manual extension lever unsecured, the cable keeping the clutch disengaged could have slipped allowing the clutch to engage  and cause the motor to stop, make sure that the clutch is not engaged by ensuring the cable is properly rigged - i.e. check the easy things first. The test for this is in the service manual too.

[ltdoyle]

I would suggest you remove the gear actuator, open it up, and inspect the gear Inside the actuator for wear.  Once they get excessive wear, they will bind and pop the breaker, esp if you still have 20:1 gears..  Older Mooneys are supposed to do this every other year, and newer ones every 500 hrs.  If you have a mechanic do this, I would watch, it's not as hard as it sounds.

[Releew]

Thanks Everyone!!

[bradp]

4 hours ago, ltdoyle said:

I would suggest you remove the gear actuator, open it up, and inspect the gear Inside the actuator for wear.  Once they get excessive wear, they will bind and pop the breaker, esp if you still have 20:1 gears..  Older Mooneys are supposed to do this every other year, and newer ones every 500 hrs.  If you have a mechanic do this, I would watch, it's not as hard as it sounds.

@AGL Aviation is doing my 200 hr now for the worm gear on the dukes actuator. 

[wpbarnar]

Please note in Rick’s original post he indicated that the gear relay circuit breaker tripped, not the gear actuator.    I think everyone assumed he has a problem with the gear actuator motor, which may not be the case.

Bill

[Releew]

Issue was resolved today.  Problem was reproduced on Jacks!  Problem source was with the lower terminals on the panel switch(LG) grounding out on the Bypass Switch cover. (located just left)   Like everything on a Mooney, the gear switch fits into a cavity.  If the switch rotates just a few degrees right (looking at the front) of the switch its very possible/probably for the LOWER terminal of the Gear switch to touch the side plate of the LG Bypass Switch as it did to me.  Pop goes the Gear Relay circuit!

The LG switch was removed and the terminals re-positioned to eliminate the possibility of this instance again.  In addition, some chafe tape was adhered to the plate cover and rubber tape applied around the switch contacts for additional protection.

Bottom line is.... the barrel of this switch has NO INDEX position to eliminate rotation.  Yes, its got a Star Washer on both sides but its not enough!  Bad design Mooney!

Check the position and security of your LG switch as alignment is critical.

Thanks for everyone input!

Rick

 

[carusoam]

Great detailed follow-up, Rick!

Thanks for sharing all the writing.

That sure is an interesting cause of the problem.

Best regards,

-a-