Unintended J bar gear extension - Yikes!

[DXB]

Well this is a first for me. Near the end of a 1.5hr flight, I was descending rather briskly at  ~1000fpm out of 7000ft in fairly smooth air, indicating ~170mph when my Johnson bar came unlatched and flew up with considerable force, striking the down lock block. This turns out to be a rather violent event that scares the hell out of everyone . Luckily the swinging bar didn't hit me or my passenger.  I also don't think anything hit the bar in the latched position in order to unlatch it  - I suspect I did not latch it securely enough on takeoff, causing it to slip out of the block after hitting a little turbulence in descent.  

Obviously 170mph is WAY above gear speed.  I cut power, pitched up, did a little dip when approaching 120mph, and relatched the gear up with minimal difficulty. Locking the gear down again before landing was uneventful.  It's my understanding that the gear itself is unlikely to have been damaged but the gear doors might be.  Once on the ground, I looked carefully at the gear doors, their hinges, and their actuating linkages and saw no obvious damage. I also inspected the up latch block and didn't see any obvious wear that would cause it to fail. Coincidentally, the 100hr AD for lube and checking gear preloads was performed by an MSC just prior to this flight. 

On the next flight I plan to pay more deliberate attention to pushing the sleeve into the block securely and also to lube that sliding part of the handle while in flight.  Am I missing the cause of the problem or any damage the event might have caused? Any other suggestions?

[steingar]

When I first go the aircraft I had a devil of a time with the Johnson bar, it was so bad I was worried I'd bought the wrong aircraft.  I had it come unlatched on more than one occasion.  The worst one was when I was flying under the shelf of the local class Charlie, can't pitch up without busting airspace.

I recall it being surprising, but not violent.  It never sprang up into the control lock either.  Of course, I wasn't doing 170 mph either.  That said, I would think that all that air resistance would retard the gear swing, not speed it up.

You might want to have a look at the lock on the floor, make certain it isn't worn.

[EricJ]

6 minutes ago, steingar said:

I recall it being surprising, but not violent.  It never sprang up into the control lock either.  Of course, I wasn't doing 170 mph either.  That said, I would think that all that air resistance would retard the gear swing, not speed it up.

The aero forces pull the gear down.   This is why it's harder to get the gear up as speed increases.   My tired gear motor will pop the breaker if I'm going too fast, but is fine otherwise.   If the bar comes unlatched at high speed I'd expect it to be pretty violent.

[gsxrpilot]

I'd bet the limitation on gear extension speed is due to the potential violence of the J-bar and the amount of force it could bring when unlatched at higher speeds. I don't believe you've damaged anything on the plane. But it could probably break an arm if one was in the way in the cockpit.

When I flew a manual gear Mooney, which I loved, I'd always give a sharp tug on the johnson bar up or down just to ensure it was properly seated and not able to come loose.

[MARZ]

Yep - it's a heck of a surprise - had it happen in the early stages of my ownership.   Got my wrist pretty good, but I still prefer it to electric - for now. 

[Ned Gravel]

18 minutes ago, gsxrpilot said:

I'd bet the limitation on gear extension speed is due to the potential violence of the J-bar and the amount of force it could bring when unlatched at higher speeds. I don't believe you've damaged anything on the plane. But it could probably break an arm if one was in the way in the cockpit.

When I flew a manual gear Mooney, which I loved, I'd always give a sharp tug on the johnson bar up or down just to ensure it was properly seated and not able to come loose.

I have dropped my gear at speeds somewhat higher than Vle and Vlo (Johnson Bar) because the gear acts as a good speed brake.  However, getting them tucked away at more than 100 mph is a real pain.  But jerking the handle once it is in either the up block or the down block is a reflex action now.

[Sabremech]

3 hours ago, DXB said:

Well this is a first for me. Near the end of a 1.5hr flight, I was descending rather briskly at  ~1000fpm out of 7000ft in fairly smooth air, indicating ~170mph when my Johnson bar came unlatched and flew up with considerable force, striking the down lock block. This turns out to be a rather violent event that scares the hell out of everyone . Luckily the swinging bar didn't hit me or my passenger.  I also don't think anything hit the bar in the latched position in order to unlatch it  - I suspect I did not latch it securely enough on takeoff, causing it to slip out of the block after hitting a little turbulence in descent.  

Obviously 170mph is WAY above gear speed.  I cut power, pitched up, did a little dip when approaching 120mph, and relatched the gear up with minimal difficulty. Locking the gear down again before landing was uneventful.  It's my understanding that the gear itself is unlikely to have been damaged but the gear doors might be.  Once on the ground, I looked carefully at the gear doors, their hinges, and their actuating linkages and saw no obvious damage. I also inspected the up latch block and didn't see any obvious wear that would cause it to fail. Coincidentally, the 100hr AD for lube and checking gear preloads was performed by an MSC just prior to this flight. 

On the next flight I plan to pay more deliberate attention to pushing the sleeve into the block securely and also to lube that sliding part of the handle while in flight.  Am I missing the cause of the problem or any damage the event might have caused? Any other suggestions?

If you find your handle harder to engage in the down block, inspect it to see if it’s bent. It will bend down near the floor and take both hands to get it in the down lock. Ask me how I know? 

David

[Ned Gravel]

Ok guys.  Some clarification is needed for this anally retentive engineer.  Down block is the one in the panel because it is where the gear is "down and locked."  Up block is in the floor because it is where the gear is up (tucked away).  

From page 8 of my E model Owner's Manual:  "The red indicator light will come on if the handle on the retraction lever is not sufficiently engaged in the down and locked position, thereby indicating an unsafe-to-land condition.  The green light indicates that the handle if properly engaged in the down position, and the gear is in the landing configuration.  A thumb operated latch is provided on the down socket to prevent unlocking the gear when it is down unless it is deliberately released."

If you say the down block is where the handle is down on the floor and the up block is where the handle is up into the panel, then I have to re-evaluate my understanding of these terms. 

 

[bonal]

I'll have to re read my POH but memory says the down block is up in the panel the up block is down on the floor. 

[Wildhorsesracing]

Also, make sure neither block is excessively worn.

[ShuRugal]

Had this happen during climbout from takeoff twice early on.  Solved it by try-flowing the snot out of my up-block, made it much easier to get the handle properly seated.  Thankfully it was at about 90 mph both times, so not violent.  Handle stopped about half way up, just barely touched my elbow.

[MyNameIsNobody]

Glad you and gear are O.K.  I am sure that really got your attention.  Way to fly the airplane and not let it distract to something more serious.

[RLCarter]

Several years ago Russell Stallings was tell me about a rear seat passenger that had inadvertently slide the handle out of the up block (the one on the floor) with his foot while in cruise, other than the surprise there was no damage

[Boilermonkey]

I've had the exact same thing happen. At the time I was new to the plane and the Johnson bar was really hard to lock down or up. The last few inches and getting the sleeve up to fully lock in either block was tough. Locking up over 80MPH was next to impossible.

After the inadvertent gear down similar to the OP I learned to always do the thumbnail check in both the up and down block. I have two other partners in the airplane that didn't seem to have the same problem, so I just continued to struggle. About 9 months ago we had new shock disks installed and I had the A&P service the whole system. I remember the first flight after that and when putting the gear up I practically punched the floor as the gear went up with so little effort.

Moral of the story, it shouldn't be that hard to swing the gear and get it in the block... and always do the thumbnail check up and down.

Sent from my SM-G960U using Tapatalk

[steingar]

I visually inspect the bar to make certain it's locked. I truly hate looking down on takeoff, but it beats an inadvertent gear release.  Truth is it only takes a second.

[DXB]

Yeah I have the habit of checking the bar is locked a million times after putting the gear down, and experience doing so has taught me that the green light is simply inadequate to ensure it is really locked.  I don't double check that it's secure after pulling the gear up and had gotten away with it for >400 hours.  I will have to work that into my routine. I think it may be best to do by feel only and not visually, particularly if one is climbing into IMC.  

 

[Yetti]

I would probably check the weld at the end johnson bar where it connects the gear linkage for cracking and bending.  split paint and such.   There was one that came unwelded at that point due to unknown causes.  

Not an IA or A&P.  And Fly electric gear so it's just a meer flip of a switch for me.

[steingar]

Biggest problem I have with the J-bar these days is I have trouble moving it when my hadn't gets sweaty.