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Landing light switch


lifendet

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Switch keeps turning off on its own after couple minutes. Unable to switch on again for a few minutes then resumes normal operation. After it shuts off on its own the switch will not stay in the on position when I try to turn it on. Any ideas? About to take a look at the wire diagram... 

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3 minutes ago, lifendet said:

Switch keeps turning off on its own after couple minutes. Unable to switch on again for a few minutes then resumes normal operation. After it shuts off on its own the switch will not stay in the on position when I try to turn it on. Any ideas? About to take a look at the wire diagram... 

Unless you want an electrical fire I wouldn't keep turning it on. I believe that switch has a circuit breaker in it.

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It's overheating. Mine did that right after I replaced the landing light the first time. Investigation under the cowl turned up cracked wire insulation, so it was replaced--no more trouble. Beats the hell out of an in-flight fire . . . . .

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2 hours ago, Raptor05121 said:

Yup, its the circuit breaker switch. Open the cowl and make sure you're not shorting out on something. Might be a good time to upgrade to LED.

Upgrade to LED or not, you will still need to find and fix the short . . . .

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Usually, if there is a short, it will blow right away. If it is slightly over current it will take a few minutes.

Those switches are bimatelic circuit breakers. They trip when a bimatelic disk heats up and looses some of its spring pressure. This allows a spring loaded arm to snap out of its detent. After they get hot, you won’t be able to reset them until they cool down.

The landing light circuit in the Mooney has the circuit breaker sized very near the operating current of the landing light. That is because it is the highest current breaker that Klixon makes in that style. The bottom line is it doesn’t have to degrade much before it will no longer carry the current of the landing light. 

You can replace the breaker and reuse the cover, replace your 250W landing light with a 100W landing light, or replace it with an LED landing light.

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47 minutes ago, N201MKTurbo said:

Usually, if there is a short, it will blow right away. If it is slightly over current it will take a few minutes.

Those switches are bimatelic circuit breakers. They trip when a bimatelic disk heats up and looses some of its spring pressure. This allows a spring loaded arm to snap out of its detent. After they get hot, you won’t be able to reset them until they cool down.

The landing light circuit in the Mooney has the circuit breaker sized very near the operating current of the landing light. That is because it is the highest current breaker that Klixon makes in that style. The bottom line is it doesn’t have to degrade much before it will no longer carry the current of the landing light. 

You can replace the breaker and reuse the cover, replace your 250W landing light with a 100W landing light, or replace it with an LED landing light.

When I was doing my spreadsheet for power loads, I looked at each component's peak draw and constant power draw. The old incandescent landing light is a big draw. I saw draws in the 6 to 8 amp range. Far less than the 20 amp breaker that i think is on that circuit.

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38 minutes ago, Marauder said:

When I was doing my spreadsheet for power loads, I looked at each component's peak draw and constant power draw. The old incandescent landing light is a big draw. I saw draws in the 6 to 8 amp range. Far less than the 20 amp breaker that i think is on that circuit.

The original landing light specified is a 250W lamp. That would be a 17.8 amp draw. at 14V. If you were seeing 6-8 amp draws then someone had replaced the 250 W lamp with a 100 W lamp. they look the same.

Edited by N201MKTurbo
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3 hours ago, lifendet said:

Thanks for all the info.. Is it suggested to replace the breaker also while replacing the landing light with LED? 

The switch will cost almost as much as the LED light bulb will.  Ouch!

Clarence

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IF it were that simple.   More than likely you will find a relay on the co pilot's firewall that is actually sending the current to the bulb.  So probably not lot of current through the switch.  There is a bus bar that the switches are attached to. Things behind the panel shift.  About the only way to see what is going behind the switches is lots of cell phone pictures.  Some people use a light and mirror.

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On 10/22/2018 at 8:39 PM, lifendet said:

Switch keeps turning off on its own after couple minutes. Unable to switch on again for a few minutes then resumes normal operation. After it shuts off on its own the switch will not stay in the on position when I try to turn it on. Any ideas? About to take a look at the wire diagram... 

+1 on the Classic worn CB switch description ...

Buy exact CB switch and replace...

yes, electrical parts wear out every half century or so...

The landing light gets used often and has a high load...

You can feel the wear... smooth operation, very light click. Compare to new.... strong click... 

Its the click that prevents it from switching off... wear out the click, the switch is done... it can’t stay on...

Old M20C experience...

Change the CB switch first... then get the new light some other day...

Also check the IP cover... when the mounts wear, the cover bumps the switch off... 

Somebody went through the effort of filing my switch to make extra room for the panel sag... ugh!

Best regards,

-a-

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