I think I need a breaker/switch...

[Nukemzzz]

So my 66E has a white strobe light in place of what was probably a mechanical rotating red beacon.  The switch/breaker combo tripped the other day in flight twice.  On the ground I was able to get it to do it again after leaving it on for about a half hour in the hangar.  I checked the wire at the breaker and it was just slightly warm before it tripped and it wasn't warm right after it tripped so it seemed like tripping wasn't warranted.  When I turned it back on the strobe didn't come back on... I tapped the switch a few times and then it did. 

So I 'think' I need one of these switches but I can't find confirmation on MS of where to actually get one.  I've spent at least an hour searching on the forum. As best as I can tell these are rare even used and I don't know if I want to go used.  I see Kilxon has some that function the same (https://www.aircraftspruce.com/catalog/elpages/klixon7270.php), that should fit, but it looks a whole lot different than stock which sucks.  Also I see 5 and 10 amp ones and I think the failed one is 6 amp (Says P7A on the back at least, the others say D6A).  For some reason the Rotating beacon switch is still there but it doesn't do anything.  The wire must be terminated somewhere.  I don't know why they didn't use the Beacon breaker when the replaced the beacon with the strobe.  It says D6A on it(6A maybe?), maybe it wasn't high enough current for the strobe? 

These switches seem to be very expensive if I find one as well.  I'm thinking of trying the beacon one since it's not used.  Before I buy one I should probably test the trip current of the one suspected to be failed...

Which switch/breaker would you recommend?  Have you come across a strobe failing in such a way that it flashes fine but then trips the breaker after a half hour or so of use?  I can't seem to find a power supply for the strobe, my guess is it is built in to this unit(The housing is pretty large).  Anyone familiar with this strobe model?  The numbers are worn off.  If I was to replace the belly strobe as well to make sure what would you recommend?

Thanks!

[Nukemzzz]

Note this are the post style switches and not the later model square rocker style.  I actually like the new version better since you can actually read what they switch does.  Mooney decided to put the labels below the switch on my plane and so you can't read them.  lol

[N201MKTurbo]

You are lucky. The toggle switches are easily obtainable. The rocker switches are, but the covers are not. 
 

If you send me the CB, I will test it for you. I have a precision Hewlett-Packard power supply.

[47U]

55 minutes ago, Nukemzzz said:

I should probably test the trip current of the one suspected to be failed...

That’s a good start, checking the breaker.  

What’s the amp rating on the strobe?  Dig back through your airframe logbook(s) and the the entry that installed the strobe should include the make and model number.  Looks like a Whelen.  The entry might even include what switch/breaker was installed to control it.  There must be a reason they didn’t use the beacon switch/breaker on the new strobe, though.  The switches do wear out, especially the higher amp ones.  Or, did your Mooney originally have top and bottom rotating beacons, hence the new strobe got its own switch?  

 

[Nukemzzz]

8 minutes ago, 47U said:

That’s a good start, checking the breaker.  

What’s the amp rating on the strobe?  Dig back through your airframe logbook(s) and the the entry that installed the strobe should include the make and model number.  Looks like a Whelen.  The entry might even include what switch/breaker was installed to control it.  There must be a reason they didn’t use the beacon switch/breaker on the new strobe, though.  The switches do wear out, especially the higher amp ones.  Or, did your Mooney originally have top and bottom rotating beacons, hence the new strobe got its own switch?  

 

Going through the logs for the strobe is a great idea. 

[EricJ]

If the wire was warm before the breaker tripped it may be because the beacon is drawing more current than it should, which is why the breaker is tripping.   The wire being cool(er) after the breaker trips would be normal because the current has stopped.

I'd suspect the beacon as much as the breaker.    Borrow a good ammeter that has as much capacity as the breaker is supposed to and see what the beacon is drawing when the breaker trips, or at least leading up to it.   An ammeter with a peak hold function would be good, since the beacon current may not be constant.  The breaker may be working as intended.

 

[Nukemzzz]

22 minutes ago, EricJ said:

If the wire was warm before the breaker tripped it may be because the beacon is drawing more current than it should, which is why the breaker is tripping.   The wire being cool(er) after the breaker trips would be normal because the current has stopped.

I'd suspect the beacon as much as the breaker.    Borrow a good ammeter that has as much capacity as the breaker is supposed to and see what the beacon is drawing when the breaker trips, or at least leading up to it.   An ammeter with a peak hold function would be good, since the beacon current may not be constant.  The breaker may be working as intended.

 

I was thinking the same with the ammeter. I need to catch it tripping and see if it’s low when it does. 

What I meant by it cold after it trips: I meant seconds after it tripped. I tried to see it was was hot when it tripped in other words. It’s a fair point though. The wire being warm at any time is a sign of significant current. 

[carusoam]

Breakers are known to wear…

but usually the landing light is the one to show it…

if the CB switch has a good click to it… it probably isn’t worn…

if you can’t feel the click… it’s probably done…

 

Send it to rich for testing…. 

-a-

[Joshua Blackh4t]

I had the same looking switches and had to replace the ones for landing light, beacon, and nav lights. The guy who I bought it off had never used any of them in the whole time he had it.

All 3 were failing about 3 minutes after they were turned on. We fitted new ones and no problems. Just not as pretty.

[jamesm]

If they align up right you might get a with a replacement. Some time the potential replacement switch/breaker might not align with electrical bus bar so then you may have redesign/rework to get it to fit which could be considered as major alteration by some.  Years ago I had  the old Circuit Breaker (the red button type) on the right side fail on me. the replacement circuit breaker  had "Line" and "Load" terminals reversed from the original circuit breaker. Not knowing the inner working of that particular that circuit breaker I mounted it upside down.

WIth the Klixon 7270-x circuit breaker being  almost $180.00 per breaker  and perhaps a suitable  substitution  Tyco Circuit Breaker W31X2M1G-XX Series  being about $40 - $44 per breaker

So how would you interpret this from Tyco's Literature regarding W31X2M1G-XX Series Circuit breaker   "0.5 amp to 50 amp ratings may be used as on/off switch."

Could  this be consider as a suitable substitution in the eyes of the FAA?

or is there more to  it that I am not seeing ?

Ask for a friend

James '67C

tycoBreakers(1).pdf

klixon7270_7271(original_left_side_sw).pdf

[M20F-1968]

I have an assortment of new Klixon switch-breakers (looks like a toggle switch with an internal breaker).  Let me know what amp rating you need, I may have one.

PM me hear, or call my cell phone at (617) 877-0025, or e-mail me at john.breda@gmail.com

John Breda

[carusoam]

Note for @Nukemzzz above…

-a-

[Nukemzzz]

2 hours ago, M20F-1968 said:

I have an assortment of new Klixon switch-breakers (looks like a toggle switch with an internal breaker).  Let me know what amp rating you need, I may have one.

PM me hear, or call my cell phone at (617) 877-0025, or e-mail me at john.breda@gmail.com

John Breda

Waiting on my A&P/IA to tell me how he would like to proceed. It’s in annual now. I’ll let you know if we decide we need a switch. 
 

Thanks!! 

[N201MKTurbo]

These breakers have a bi-metallic disk that acts as a spring that holds the switch lever in place when it is in the on position. The circuit breaker current passes through the disk. There is a spring that is trying to pull the lever to the off position. The lever has an insulated bump that goes into a small hole in the disk. If the disk heats up from excessive current, it relaxes its hold on the bump on the lever and the spring pulls the bump out of the disk.

The current carrying capacity of the breaker is reduced by ware on the bump and hole which happens by thousands of actuations. A breaker switch that has rarely been actuated, is unlikely to lose its capacity. One that is actuated often may lose it ability to carry its rated current.

My offer still stands for testing the the breaker, just send it to me with return postage and I’ll test it and return it the same day. I can do breakers up to 10 amps.

[Nukemzzz]

Hey guys, update…

We tried and tried and couldn’t get the issue to repeat during annual to troubleshoot if it was the switch or the strobe. It has been fine since and I reasoned it just needed to be exercised. 
 

Until today!
 

Today it popped and I noted the back of the switch box itself was very hot. It was able to burn my finger if I held it there too long. The wires weren’t hot, just the body of the switch. I let it cool and flipped it back on and it slowly heated back up. The strobe kept flashing as it heated up so it wasn’t a short in the strobe circuit. Also, It seemed like when I increased engine RPM and the voltage increased it heated up really hot then until it popped again. 

My guess is the switch itself is failing in such away that it is generating internal heat which causes it to pop. I’m not an electrical engineer…is this likely?  If so, I think my next step is a switch. I just need to figure out what amperage is needed. I’m going to get the strobe manual from my things tomorrow and see what the book says is required  it might just be that the worn out switch amperage capability is just too close to the strobe requirement.

thoughts?

Sucks because I’m literal a couple of weeks away from my PPL checkride. I’m that close!   I appreciate the offers to test things but I’m more likely to just pick the strobe or switch and just put in a new one for sake of time. 

[Nukemzzz]

Does anyone know what switch part numbers are direct replacements so it fits in the same place and the bus bar doesn’t have to be modified?  I see tyco…but is it the same fittment?  I suspect it’s cheaper but you pay the difference in labor/time for tweaking things to make it fit. I willing to pay for the more expensive switch if it is drop in. Just don’t what switch that would be. 

[carusoam]

53 minutes ago, Nukemzzz said:

Does anyone know what switch part numbers are direct replacements so it fits in the same place and the bus bar doesn’t have to be modified?  I see tyco…but is it the same fittment?  I suspect it’s cheaper but you pay the difference in labor/time for tweaking things to make it fit. I willing to pay for the more expensive switch if it is drop in. Just don’t what switch that would be. 

Go to the AircraftSpruce website look up circuit breaker switches, select amperage that you have in there…

The pictures they have should match what yours looks like…

 

These things are both electrical and mechanical…

When they start misbehaving their resistance to electrical flow increases… and so does it’s temperature…

The device senses temperature and opens the circuit…

Resizing the circuit breaker… only if it is the wrong size… not based on the way the one in the panel is behaving… that would lead to a different more dangerous problem…

 

If you think the mechanic that installed the parts used the wrong breaker… find out what hardware is connected to the circuit and look up its requirements in the installation information… if it is Whelen hardware….  We have a Whelen guy around here…

High current devices have a tendency to wear out the mechanical switch… you can tell how worn out it is because it’s click wears out as well… it is an over center device that becomes easier to go over center… with wear…

PP thoughts only, not a mechanic… or electrical engineer.

Best regards,

-a-

[Nukemzzz]

I'm fairly sure that my plane uses D7270-5-xx model toggle switch breakers.  I suspect also that the 7270-5-xx is the same switch.  I don't know what that 5 means.  I see 1's and 7's as well.  The xx on this switch that is kicking is a D7270-5-5 ... so I think it is a 5amp.  I'll check the strobe docs tomorrow to see if 5amp is supposed to be enough.  

 

@M20F-1968 do you have this model?  I'll probably call you tomorrow.

 

Thanks guys

[carusoam]

AS… doesn’t show all of the options…

https://www.aircraftspruce.com/catalog/elpages/klixon7270.php

 

Sensata / Klixon will have them all…

One is the manufacturer… the other is the sales retailer…

If AS doesn’t show what you want…  a phone call will fill in the rest of the details…

The other route… Call Dan at Lasar…

Best regards,

-a-

 

[chriscalandro]

I had the same thing with my landing light. If the internal contact starts to corrode it can make it hot as well as not as much of the contact is … in contact. 
 

instead of replacing the switch I just got an LED replacement landing light. Problem solved. 
 

your problem could be either the switch or the beacon. Replacing the beacon with an led replacement gets you a better beacon and probably solves the problem either way by not pulling enough power to flip the weakened switch, and by replacing a potentially bad beacon. 

Edited April 28, 2022 by chriscalandro

[Nukemzzz]

2 minutes ago, chriscalandro said:

I had the same thing with my landing light. If the internal contact starts to corrode it can make it hot as well as not as much of the contact is … in contact. 
 

instead of replacing the switch I just got an LED replacement landing light. Problem solved. 
 

your problem could be either the switch or the beacon. Replacing the beacon with an led replacement gets you a better beacon and probably solves the problem either way by not pulling enough power to flip the weakened switch, and by replacing a potentially bad beacon. 

I’m considering the same. 

Tomorrow I’m going to see but 2 of the adjacent switches switches aren’t in use. If they are the same amperage I may move the strobe wire over to it and see.  If not, then my next move is likely an LED strobe.   These switches are $300+after tax and shipping.  Can get a strobe for that. Lol

[carusoam]

Tech detail sheet for the Sensata / Klixon switch…

https://www.sensata.com/sites/default/files/a/sensata-7270 7271 series-toggle switch circuit breaker-datasheet_1.pdf

They have a chart for the available Amp requirements…

Any questions… ask your mechanic…

Best regards,

-a-

[Nukemzzz]

So I may have another solution: ditch the belly strobe (patch the hole) and install wingtip led nav/strobes. Reduces drag and I don’t even need this breaker any longer. Hmmm. 

Apparently since I have open wingtips it meets anti collision light requirements. 

[carusoam]

If you fly at night…

More strobes are better than less…

Even when the regs allow less…

 

Strobes are pretty good in daylight as well… extra handy around uncontrolled fields…

Best regards,

-a-

[Robert Hicks]

If you need a new switch I can grab you one. I have a bunch at the hangar and access to the junkyard with several mooneys here in Phx. Send a PM if you wanna travel down this road.