Troubleshooting a Klixon switch

[Matt Ward]

I’ve been having an intermittent problem with my strobes, a Whelen A413A. The switch is a Klixon 10 amp CB I think. It’s pictured below. For a while, it’s been “stiff” to move from the off position to the on position. Recently all strobes stopped working and oddly the stiffness seemed to go away. A few flights later they started working again. I’m evaluating this on/off behavior during preflight by the way. It seems like a likely candidate is the switch has turned unreliable. But before I replace it, is there any additional troubleshooting I should do? And, any switch I should use instead of trying to find the Klixon replacement?

thanks!

 

[RLCarter]

You can check the resistance on the switch 

[N201MKTurbo]

Just to be completely legal, you need to replace it with the same switch. Those are readily available. 

Before you replace it, shoot a bunch of tri-flow into it and work it on and off and see if it gets better.

[N201MKTurbo]

https://www.opentip.com/search.php?cPath=30540&products_id=8258872&gclid=EAIaIQobChMI3tvFtpXr6QIVxz2tBh2AlQrlEAQYBCABEgIx0_D_BwE

 

 

[Guest]

4 hours ago, N201MKTurbo said:

Just to be completely legal, you need to replace it with the same switch. Those are readily available. 

Before you replace it, shoot a bunch of tri-flow into it and work it on and off and see if it gets better.

Or drown it in LPS#1 

Clarence

[Ragsf15e]

You can drown it in several cans if lps1 and not get close to the $200 it costs to replace one dang switch!
 

Follow these guys advice, check the resistance, make sure the wires are tight.  I have heard that the switch/cbs wear out and eventually won’t stay on anymore when they need replacing.  Yours sounds different.

[carusoam]

How old is it?

How many amps goes through it?

They wear, and lose their click, over time...

Having too much click, sounds like it may be dirty or broken...

Lights that get used a lot have a tendency to wear The cb switch ...

Takes less time to replace than it does to troubleshoot...  So do the best you can with cleaning...

PP thoughts only,

-a-

 

[Tahir K]

How old is it?
How many amps goes through it?
They wear, and lose their click, over time...
Having too much click, sounds like it may be dirty or broken...
Lights that get used a lot have a tendency to wear The cb switch ...
Takes less time to replace than it does to troubleshoot...  So do the best you can with cleaning...
PP thoughts only,
-a-
 

Some of my switches don't stay on anymore. Will I need to completely replace them with the ~200 switches linked above?

[Ragsf15e]

Likely.  Be careful, some are more important than other (fuel pump or pitot heat vs nav lights).  They are different amperage too.

[carusoam]

Having CB switches that automatically turn off without warning can be a problem...

There are two known causes for this...

1) The worn switches is pretty obvious when compared to a new one... a quick click comparison...  

2) panel sag...older Mooneys with an instrument panel mounted on rubber mounts... when the mounts break or wear out or get loose... the panel moves down enough to bump switches in the on position... 

I learned about this in my M20C... the PO had ground the plastic at the top of the landing light switch toggle... to allow for a few MMs of extra space...
 

When considering swapping in new CB switches...   Just know they are all attached to a brass bar at the back... this bar has to be removed to get the single switch that you want out.... Lots of screws holding it in place...  External access panels to the back of the radio stack is a god-send for this...

PP fuzzy memories only, not a mechanic...

Best regards,

-a-

[Ross Taylor]

We've got a '66 E which we bought early last year.  I found that if I left the landing light on for any length of time, then turned it off, it wouldn't come back on until after some cooling time.  It never switched itself off, but if I turned it off that's when it would balk.  So, I didn't turn it off near the field.  Switching my landing light to an LED bulb solved that...for now.  The current draw is lower, so there's less heat build-up in the breaker.  But I expect that someday (maybe 20-30 more years) even the LED draw will cause issues with heat, due to the wear inside the CB switch detent.

[Tahir K]

Is there a more permanent solution for this other than just replacing $200 switches everytime it goes bad in the near future? Maybe replacing all the switches with a different type. I wonder if rocker switches go through this as well.

[N201MKTurbo]

16 minutes ago, Tahir K said:

Is there a more permanent solution for this other than just replacing $200 switches everytime it goes bad in the near future? Maybe replacing all the switches with a different type. I wonder if rocker switches go through this as well.

Lousy crap switches, it is like you have to replace them every 60 years! What do you have to do to get quality products these days?

[Ross Taylor]

16 minutes ago, Tahir K said:

Is there a more permanent solution for this other than just replacing $200 switches everytime it goes bad in the near future? Maybe replacing all the switches with a different type. I wonder if rocker switches go through this as well.

In terms of function, a regular SPST switch in a circuit protected by a circuit breaker would be totally fine.  The breaker would last longer, as it's not being cycled regularly, and the switch is cheap.  Unfortunately, I don't think its allowable without an STC or whatever rule would apply here...

[Tahir K]

Lousy crap switches, it is like you have to replace them every 60 years! What do you have to do to get quality products these days?

It's ridiculous! Why aren't they indestructible!!!

[Andy95W]

14 minutes ago, Ross Taylor said:

In terms of function, a regular SPST switch in a circuit protected by a circuit breaker would be totally fine.  The breaker would last longer, as it's not being cycled regularly, and the switch is cheap.  Unfortunately, I don't think its allowable without an STC or whatever rule would apply here...

Actually, I did exactly this.  By the FAA definition, it is a minor alteration.  I wrote it up on a 337 as such and my FSDO agreed.  Technically, a 337 isn't even required for a minor alteration, but I filed it anyway because in that form it helps serve as a permanent part of the aircraft records that modifies the information in the Owner's Manual.

I fabricated a dedicated bus bar for the components controlled by those breaker switches on the pilot side.  I used switches and circuit breakers that were MIL-SPEC.  I used wire that was appropriate for the current based upon AC 43-13.

[Andy95W]

Ross, if you're re-doing your panel and your A&P/IA is agreeable, I'll email you a copy of that 337.

[EricJ]

6 hours ago, Ross Taylor said:

In terms of function, a regular SPST switch in a circuit protected by a circuit breaker would be totally fine.  The breaker would last longer, as it's not being cycled regularly, and the switch is cheap.  Unfortunately, I don't think its allowable without an STC or whatever rule would apply here...

As mentioned a minor or major modification, either of which are doable.   Which it is and how hard it might be depends mostly on your A&P and IA.    It might be pretty trivial.

[Ross Taylor]

1 hour ago, Andy95W said:

Ross, if you're re-doing your panel and your A&P/IA is agreeable, I'll email you a copy of that 337.

That is super kind of you, but I'm not doing that anytime soon. I was just trying to provide a little input from my electrical engineering perspective for the original poster. 

But I am glad to hear it's not a big deal to do it. When that time comes I'll certainly consider it as an option myself.

Thanks much!

[MikeOH]

Heretic warning!!!  (And, I'll likely lose my CB membership over the following comment)

Yeah, 185 bucks for a protected switch is WAY over the top STUPID.  However, even with my limited ownership experience I long ago decided anything under an AMU is just not worth sweating over.  Sure, you can buy a MIL-SPEC switch for $20 and a breaker for $35, go through the hassle and time of figuring out how to mount it, find a friendly A&P (assumes he will work for free, or add in his cost) to figure out how to make it legal, and, guess what?  You saved, maybe, $125.

Now, don't get me wrong, IF you enjoy stuff like this as much as flying the plane itself, then I can totally see this...you save a small amount, accomplish something you're proud of, and feel great!  In my younger days, I enjoyed that kind of thing.  Maybe when I retire, I'll feel that way again.

Meanwhile, I'd have already ordered the $185 switch from Spruce, and installed it(yes, with proper A&P supervision).

[gsxrpilot]

I'm afraid the Klixon switch for my Aspen went out on the flight from BJC to BIL on Friday. The Aspen when onto battery power for the rest of the flight. Nothing else in the panel was effected and the EDM900 reported full voltage and good amp draw as usual the entire flight. I'll role her into Aerotronics here in Billings Monday morning and see if they can sort it out for me.

[Matt Ward]

11 minutes ago, gsxrpilot said:

I'm afraid the Klixon switch for my Aspen went out on the flight from BJC to BIL on Friday. The Aspen when onto battery power for the rest of the flight. Nothing else in the panel was effected and the EDM900 reported full voltage and good amp draw as usual the entire flight. I'll role her into Aerotronics here in Billings Monday morning and see if they can sort it out for me.

Aww man, it’s Klixon dying season! Let me know if you get jammed up and need a ride home from BIL. Easy flight from here. 

[carusoam]

Be aware... Klixon cb switches are temperature sensitive, they trip based on heat...  

They have been wearing for a year, since it was this warm last...

It could be a Seasonal die-off...  

 

Somebody found a good reason to have ordinary switches connected to ordinary CBs.

They found some awesome modern aviation lighted switches... That fit in the ordinary places...

It will look like you are flying an M20U if you go this way...

Best regards,

-a-

[gsxrpilot]

On 6/7/2020 at 7:25 PM, Matt Ward said:

Aww man, it’s Klixon dying season! Let me know if you get jammed up and need a ride home from BIL. Easy flight from here. 

Thanks! The avionics shop in Billings took good care of me. I took off for home and got as far as Casper. There is some serious weather between here and Denver tonight. I'll get home in the morning.