Gear switch broke in half?

[toto]

Plane is in the shop for annual. The inspection is just about finished, one of the last things was the gear swing. Apparently when the lever was put down, the handle just snapped off .. ??

I’ve never seen anything unusual with the gear handle, it’s always worked perfectly.

Has anyone seen this before?

[MikeOH]

YOWZER!

I guess anything is possible (metal fatigue), but that sure looks like someone tried to force the switch up without pulling out first!

[Fix]

If the remaining bit that is left works as it should, then most likley someone use to much force.
 

[flyboy0681]

On the outside chance that this can happen due to normal use, I carry needle nose pliers in my flight bag - just in case.

[Vance Harral]

Broken gear switches like this are not unheard of.  We added a member to our airplane partnership many years ago who managed to snap the switch off on his initial training flight, just like is shown in the OP's photo.  Yes, the damage occurred because he didn't fully understand the pull-out-to-unlock mechanism of the switch, and broke it while trying to raise the landing gear (which fortunately resulted in the gear remaining in the down and locked position).  But he's not the first person to break a Mooney gear switch, and I think it's likely the switch shaft gets fatigued over time even in normal operations.

I'm sure someone will argue the switch lasts indefinitely with gentle use.  But I think it's fair to criticize the design.  The fact there have been multiple incidents of switches breaking is a legitimate design issue.  Other gear switches in other aircraft are considerably more robust, albeit at the expense of being larger and heavier.

[MikeOH]

@Vance Harral

While you raise an interesting point about the design, that begs the question, "What is a sufficiently robust design"?  IOW, just how 'idiot proof' must a design be before "it's the user's fault"?  Sorry, but in this case I am going to blame the user.  That type of locking switch has been around for decades, in many applications.  Even this 'small' switch requires a very large amount force to break the switch handle off!

If a new pilot or mechanic to the Mooney (or any other machine) FAILS to obtain proper training and damages the equipment, THAT is NOT a design defect, IMHO.

For OP, trying to prove that is likely near impossible, however.  It is likely the shop will deny any wrongdoing and claim the switch was 'end of life' and proceed to charge him for a new switch and the labor to install.  Frankly, I'd be steaming mad; likely I would not return to the shop again.  But that's just me

[Vance Harral]

23 minutes ago, MikeOH said:

IOW, just how 'idiot proof' must a design be before "it's the user's fault"?

That's a fair question, but it's equally fair to ask, "How many times must something fail in the field before the community admits that maybe it's not a great design?"  We've got the OP's broken switch story, my broken switch story, and here's another Mooneyspace thread with yet another broken switch story.  So we know the switch shaft failure isn't exactly rare.

For better or worse, it's human nature to deflect responsibility.  In the engineering profession (I'm of that tribe and I know you are too), that manifests as blaming operators when your stuff fails, instead of accepting responsibility for making a product easier to use and/or more tolerant of mistakes.  It really is the operators fault sometimes, of course, I get your point about "idiot proof".  But you've also gotta be cognizant of your own biases, and your defense of the switch in this case feels like that engineering design bias.  Not that anyone particularly cares about my opinion, but I wouldn't use a landing gear switch this fragile in a new aircraft design, despite that fact that it's "been around for decades in many applications"

[N201MKTurbo]

You should be careful, or there will be an AD and we will all have to buy new switches.

[Ragsf15e]

48 minutes ago, N201MKTurbo said:

You should be careful, or there will be an AD and we will all have to buy new switches.

Here comes the J-bar mafia with their bragging again…

[Vance Harral]

5 minutes ago, Ragsf15e said:

Here comes the J-bar mafia with their bragging again…

Well, which problem would you rather have: an electric gear switch that rips off in your hand, or an ovaled-out lock block that unlocks the gear uncommanded?   

[varlajo]

11 minutes ago, Ragsf15e said:

Here comes the J-bar mafia with their bragging again…

That's all good and fine until your A&P calls you saying that your J-bar has just snapped in half.. 

[Pinecone]

It looks like over 4000 electric gear Mooneys built.  3 failures in 4000 aircraft over more than 40 years.

I think the design is robust enough.

[MikeOH]

2 hours ago, Vance Harral said:

That's a fair question, but it's equally fair to ask, "How many times must something fail in the field before the community admits that maybe it's not a great design?"  We've got the OP's broken switch story, my broken switch story, and here's another Mooneyspace thread with yet another broken switch story.  So we know the switch shaft failure isn't exactly rare.

For better or worse, it's human nature to deflect responsibility.  In the engineering profession (I'm of that tribe and I know you are too), that manifests as blaming operators when your stuff fails, instead of accepting responsibility for making a product easier to use and/or more tolerant of mistakes.  It really is the operators fault sometimes, of course, I get your point about "idiot proof".  But you've also gotta be cognizant of your own biases, and your defense of the switch in this case feels like that engineering design bias.  Not that anyone particularly cares about my opinion, but I wouldn't use a landing gear switch this fragile in a new aircraft design, despite that fact that it's "been around for decades in many applications"

Well, when it comes to apparent bias, I think your willingness to blame the design appears biased, as well  As far as 'blaming the user', that's software engineers, not hardware engineers

Do we really know this "isn't rare"?  How many aircraft over how many years have actually had this failure mode? You claim three examples, but let's look at each one. (EDIT: I see @Pinecone provided that answer)

The OP did NOT do this himself; we do NOT know the training level of the individual whose hand was on the switch when it broke in this manner (I note you ignored my earlier points about a TRAINED operator.  It takes a lot of force to break that handle off; well past 'tolerating' an honest mistake*).

Your third example is NOT the same failure mode; your link shows an image that the PLASTIC wheel of the switch broke. NOT the metal switch handle itself which was still intact; the gear switch could still be easily operated.

Finally, what were the details of your switch failure? Were you the operator when it broke? Did it shear off the metal handle such that it could no longer actuate the gear, or something else that failed?

I just don't see the evidence that this is a 'fragile' design that you do.  IOW, I don't think the appropriate corrective action is to replace the switch with one so robust as to cause a bent instrument panel before the switch breaks when improperly operated.  Another alternative would be to ELIMINATE using a locking switch design.  Would you be willing to blame the user for inadvertent switch activation and subsequent gear ups in that case, or would you blame that on 'poor design', as well?

 

* I have encountered these 'locking' switches many times over many decades and have NOT always realized they were of locking design.  After having applied a pretty decent amount of force without switch movement, I then realized they were, in fact, a locking design.  Whereupon I pulled out the handle before moving it.  IOW, these switches ARE properly engineered/designed with a sufficient degree of robustness to account for operators NOT initially realizing they are locking switches.  I.e., they are tolerant of a reasonable mistake.

[MikeOH]

For the OP, here's how I think this played out (yes, speculation on my part):

Plane was on its wheels.

Mechanic jacked up plane.

Mechanic asked untrained/unfamiliar/newbie assistant to climb in the cockpit and raise the gear when told, so that mechanic could observe operation.

Mechanic said, "raise gear"

Assistant tried to move switch, got impatient (maybe mechanic yelled, "I SAID GEAR UP!!!), FORCED switch until it broke

Mechanic sent helper away to sweep the corner of the hangar.

Mechanic took pile of parts to boss and said, "Switch broke"

[Hank]

2 hours ago, Vance Harral said:

it's human nature to deflect responsibility.  In the engineering profession (I'm of that tribe and I know you are too), that manifests as blaming operators when your stuff fails, instead of accepting responsibility for making a product easier to use and/or more tolerant of mistakes.  It really is the operators fault sometimes, of course, I get your point about "idiot proof".  

Back when I was a Manufacturing Engineer on the plant floor every day; writing and updating procedures and work instructions; keeping an eye on equipment; and supervising my guys who took care of it, i kept this taped to my monitor for constant reminding when I was writing anything for the operators:

Nothing is foolproof to a sufficiently talented fool.

Like the operator running a machine with two working positions--both hands were on the two joysticks to move from one to the other. I had to redesign the station so that the operator could.hold the joysticks in position while turned around backwards to talk to someone, because an operator did that and the table hit her elbow due to the unnatural arm position and lack of attention. 

Same thing applies to the landing gear switch. If the operator doesn't try to force it, but instead pulls it out before moving, it's not a problem. How much force do you think the new all-metal switch should withstand before bending or breaking?

[varlajo]

4 minutes ago, Hank said:

Nothing is foolproof to a sufficiently talented fool.

[PT20J]

This should do it. 

[JTR]

1 hour ago, MikeOH said:

For the OP, here's how I think this played out (yes, speculation on my part):

Plane was on its wheels.

Mechanic jacked up plane.

Mechanic asked untrained/unfamiliar/newbie assistant to climb in the cockpit and raise the gear when told, so that mechanic could observe operation.

Mechanic said, "raise gear"

Assistant tried to move switch, got impatient (maybe mechanic yelled, "I SAID GEAR UP!!!), FORCED switch until it broke

Mechanic sent helper away to sweep the corner of the hangar.

Mechanic took pile of parts to boss and said, "Switch broke"

Best theory.  
 

My wife did this to me when I asked for gear up.  She had just passed her PPL in a 172 and wanted to fly our Ovation. Im typed in the CJ and 560 series and we had a dream to become husband wife team.  She wanted to be SIC someday.  She does a great walk around, take off and I said "gear up"...she handed me the switch.  She was nervous and trying to make a good impression.  My fault for not teaching her before we got in the air.  

[IvanP]

17 hours ago, toto said:

Plane is in the shop for annual. The inspection is just about finished, one of the last things was the gear swing. Apparently when the lever was put down, the handle just snapped off .. ??

 

 

Yes, the handle "just snapped off" all by itself  . Your shop should own up to the fact that thay were doing a gear swing and had a hamfisted kid who was probably not familiar with Mooney manipulating the gear switch. S&^% happens. Nobody is perfect, but they should apologize and replace the switch at no cost to you. You gave them a plane with working switch , they broke it - simple as that. 

[toto]

1 minute ago, IvanP said:

Yes, the handle "just snapped off" all by itself  . Your shop should own up to the fact that thay were doing a gear swing and had a hamfisted kid who was probably not familiar with Mooney manipulating the gear switch. S&^% happens. Nobody is perfect, but they should apologize and replace the switch at no cost to you. You gave them a plane with working switch , they broke it - simple as that. 

The shop’s theory is that the handle was corroded and was just waiting to snap - and it was sheer luck that it happened on jacks instead of in flight. 

[Vance Harral]

2 hours ago, Pinecone said:

It looks like over 4000 electric gear Mooneys built.  3 failures in 4000 aircraft over more than 40 years.

Oh c'mon, this is just stupid. The fact I only pointed out 3 examples doesn't mean there have only been 3 failures ever.

1 hour ago, MikeOH said:

Your third example is NOT the same failure mode; your link shows an image that the PLASTIC wheel of the switch broke.

Look at the picture yourself, from that thread.  More than half of the threaded portion of the attach point for the plastic wheel-shaped knob is broken off.  This is not just a failure of the plastic.  If you want to quibble that a different part of the metal shaft broke vs. the OP in this thread, then sure, it's a different failure mode.  Whatever.

 

 

1 hour ago, MikeOH said:

Finally, what were the details of your switch failure?

Same as the OP in this thread, the shaft broke close to the base such that it could have only been actuated with tools.  No, I wasn't the guy with my hand on the switch, but I believe my airplane partner when he said he applied only a moderate amount of force.

Some of you guys seem to think these switches can only break when a neandrathal lunk applies hundreds of pounds of force to the switch without pulling it out of the unlock position.  I'm not buying it.  If that's what's really happening, why do the little locking tabs that prevent the shaft from moving - which are smaller than the shaft itself - show no damage in the photos above?

2 hours ago, MikeOH said:

IOW, these switches ARE properly engineered/designed with a sufficient degree of robustness to account for operators NOT initially realizing they are locking switches.

I'm sure that's true when they're brand new.  As I've already explained, I think decades of normal use - with a few incorrect operations exactly as you describe from time to time - can fatigue the metal.  As I recall, you're the same guy who keeps arguing that properly lubricated landing actuator gears will also never wear out.  You have a lot more faith in the lifetime of this stuff than I do, but you do you.

34 minutes ago, PT20J said:

This should do it. 

Good point.  Why do some airplanes have big, robust gear switches, if there's nothing wrong with the design of the tiny little ones?

13 minutes ago, JTR said:

My wife did this to me when I asked for gear up.

Now we have 4 stories.  But I guess everyone who broke the gear switch - the OP's mechanic and my airplane partner and JTR's wife included - are all ham-fisted idiots who deserve what they get.  Roger that.

[IvanP]

3 minutes ago, toto said:

The shop’s theory is that the handle was corroded and was just waiting to snap - and it was sheer luck that it happened on jacks instead of in flight. 

Of course, it is.. Landing gear switches are continuously exposed to highly corrosive environment in the cabin and all metal parts corrode to the point of structural failure when the slight force necessary to flip a switch is applied. Another plausibe theory is that it was caused by climate change. Anyting but someone's error. 

I do not know your mechanic, but corrosion appears to be highly unlikely cause of this incident. IOW, I call bulls&^%.  But I have been wrong many times before so I would be open to see some evidence of the "corrosion".  

[JTR]

11 minutes ago, Vance Harral said:

...JTR's wife included - are all ham-fisted idiots who deserve what they get.  Roger that.

She was ham fisted for sure, but not an idiot by any means (masters degree and raised one daughter in medical school and 2 young men now at West Point).

It looked just like the original poster's picture when it happened.

[MikeOH]

38 minutes ago, toto said:

The shop’s theory is that the handle was corroded and was just waiting to snap - and it was sheer luck that it happened on jacks instead of in flight. 

I sure didn't see ANY evidence of corrosion.  Can they show you?

Also, while not a metallurgist, I'll bet someone who is could determine if this was a fatigue failure (i.e. cumulative damage) vs. a single-event over stress (which this sure looks like to me).

[N201MKTurbo]

Mooney has used many different landing gear switches over the years.

I would blame the one holding the little wheel when it came off.