Johnson Bar motion

[Matt Ward]

Hey guys, 

When flying today, I had a new experience in the Mooney. When approaching to land, I swung the bar, tried to lock it, and the little orange light stayed lit! After fiddling with it and having no luck getting a green light, I did a full reset: back to the bottom, one firm continuous motion, green light! Anyways it got me wondering: is there any backup procedure if you can’t get a green light? Anything to check in preflight to give you confidence all is well? Anything more to think about? I love the Johnson bar for its simplicity and (I think) nearly full-proof-ness.

Thanks!

[carusoam]

Matt,

Did you join MS too late to see the new round of discussions about updating your down lock block?

read up on the thumb nail check...  the known test to make sure your gear is fully down, and locked...

If the light is not showing you the gear being down and locked... it’s a good chance it isn’t.... be extra careful...

 

There is a possibility that the sensor needs to be adjusted... it resides in the down lock block...

Too many gear up accidents have occurred for lesser reasons...

PP thoughts only, not a mechanic...

Best regards,

-a-

 

[takair]

7 minutes ago, Matt Ward said:

Hey guys, 

When flying today, I had a new experience in the Mooney. When approaching to land, I swung the bar, tried to lock it, and the little orange light stayed lit! After fiddling with it and having no luck getting a green light, I did a full reset: back to the bottom, one firm continuous motion, green light! Anyways it got me wondering: is there any backup procedure if you can’t get a green light? Anything to check in preflight to give you confidence all is well? Anything more to think about? I love the Johnson bar for its simplicity and (I think) nearly full-proof-ness.

Thanks!

A few things to check.  Did the red light go out or stay on?  They are just alternate switch positions.  Did the thumb latch seat?  When you put the gear up, you can stick your finger in the hole on the downlock block and push the switch to see if the bulb is good.  This is a good check for the situation you were in. As Anthony suggested, you may have a slightly worn block.  While we had an owner made parts buy, LASAR stocks them and they are not that much more than the owner made parts.  

[Matt Ward]

Yes to be clear, no incident. It just took two swings and green light on and red light off!

[carusoam]

There is also a good visual of what a worn block looks like posted yesterday...

I’ll see if I can bring that thread up...

[Matt Ward]

I found this in case it’s helpful to others too. 
http://donmaxwell.com/operating-the-manual-landing-gear/

 

[carusoam]

Don posted a few pics at the end of this thread...

The hole in the block is supposed to be straight through, and cylindrical...

You can see an egg shaped hole, with a step in it...

 

The step interferes with the proper operation...

When you fly... you can put your phone up to the hole and take a pic... (best to have somebody else do the picture taking...)

Many people would put their plane up on jacks for this...

Best regards,

-a-

[skydvrboy]

Maybe a dumb question, but did anything get stuck in front of the bar? I’ve seen this with carpet, the center console, and even a pee bottle once... fortunately empty! 

[midlifeflyer]

10 hours ago, carusoam said:

read up on the thumb nail check...  the known test to make sure your gear is fully down, and locked...

Assuming it's not a system problem such as a loose light or worn block or switch, it might simply be the light was correct and it did not seat completely on the first attempt. 

Definite motion to seat, manually raise the collar, confirm light, shake the stick to see if it comes out, and thumbnail check.  Yep, I'm paranoid about the landing gear

(and yes, I did once have the handle pop out on the shake)

[Shadrach]

10 hours ago, Matt Ward said:

I found this in case it’s helpful to others too. 
http://donmaxwell.com/operating-the-manual-landing-gear/

 

It's good the you recycled the gear.  There is a limit switch in the down lock socket as Mark referenced above (you can feel it with your finger when the gear is retracted).  On the rare occasion that the bar stops short short of seating, pushing forward and up on the knurled lock usually does the trick. 

[M20F-1968]

The two gear lights are driven by the switch in the down lock block and a reference to a switch on the throttle cable.  About 12.5" of manifold pressure and gear still up triggers the gear horn.  The green light may not come on because the switch position has moved.  There is a long tang on the switch which may need adjustment or the switch may be mechanically loose of have moved from its idea position.

The Johnson bar is great for its simplicity in operation and design.  If the Johnson bar is securely in the down lock block, it doesn't matter what the lights show.  The yellow or red light (depending upon your plane) show that the gear is likely up and advises you to look further.  If you have a yellow or red light and believe the gear is down, grab the handle and pull down, try to get the handle to come out of the down lock block.  If the end of the thumb-lock (chisel shaped) is engaged in the groove in the handle, the handle will not come loose without pushing the thumb release.  If the handle does release with a downward pull without pushing the thumb-lock, the bar is not secure.  Trying to pull the J-Bar handle aft is not a test.  Trying to pull down is.

The best aspect of the J-bar is that you can feel and test with your hand the condition of the Johnson bar and gear.  If the Bar is properly engaged, all 3 wheels are down (provided the gear are rigged properly).  

[Matt Ward]

Here are a couple pictures of the locking mechanism. Sorry they are so blurry! How does this look to you guys? No problems today at all. 

[carusoam]

Matt,

That is exactly the right picture...

you can see the tang across the hole that activates the switch...

and all the lock mechanism attached to the button...

 

The color of the block doesn’t look like the beige originals...

the clarity of the picture kills any further observations I can make...

 

If you are understanding the pulling down on the handle lock test... the thumbnail test...

You probably will hear/feel the click of the lock pin enter the hole while putting the gear down...

 

Getting it right requires Down and Locked...

Not locked only takes bumping the gear over center to fold up...

PP thoughts only, not a mechanic...

I put an arrow on your pic... this is where the egg shaped wear occurs, the ridge will be further up the hole...

The wear causes the J-bar to not go all the way up the round hole where it belongs...

Best regards,

-a-

 

[gsxrpilot]

I'm happy to meet you out at BJC and go over the whole system with you. The Mooney manual gear system is excellent in so many ways. And one of them is not having to rely on lights, mirrors, or other secondary indications of gear position. You can literally grab the gear and pull on it to verify it's down and locked. 

Give me a call. Happy to go over it with you.

[hammdo]

I see a ridge in the middle of the block very similar to mine. I’d turn the flash on for the camera and see if it’s as pronounced as it appears. That doesn’t look like the original block. I’d check the logs to see when it was replaced.

Edit:

Added the pic from my thread..

-Don

[Matt Ward]

You guys were right: on 9/23/2004, Top Gun Aviation in Stockton, CA noted in the logbook: "replaced gear lock down assembly".  So that was about 16 years ago, about 1200 tach hours.

[hammdo]

Good to know. I’d get that ridge inspected to make sure that did not contribute to your experience. Laser has new blocks btw if it is out of spec. Quick install based on what my AP told me on mine...

-Don

[bonal]

Had this problem about a year ago and this was with a fairly new down lock block from Lake Aero. Would not give me the green light unless I made a real deliberate upward push. A little tri flow on the slider and problem went completely away.