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Nav light problem.


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Last night when I switched off my landing light on my departure I accidentally switched off my nav lights. No biggie, but the problem was that they wouldn't switch back on. The rocker switch itself wouldn't lock in place so I turned into the downwind for a return back to the runway and assumed I popped a breaker but to my inspection I didn't. As I turned base in anger I pushed the switch again and I had my nav lights back. Went home and the same thing happened again, a few minutes later I was able to switch them back on. Please note they will stay on for hours with no sign of a short or faulty wiring any ideas?

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Does your 74 have the Klixon type of switch? If so, the switch is the breaker. The failure mode for the Klixon I have had fail are either the cover falls off or the switch won't won't latch. The replacements are expensive coming from Sensata.

You have a 20TC-5 or 10. The 5 and 10 denote the amperage rating. http://www.sensata.com/download/klixon-circuit-breaker-aircraft-catalog.pdf

You may find some on eBay from time to time or someone on the site may have a spare to sell.

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Temperature sensitive circuit breaker / switches have a tendency to wear.  It is usually the headlight CB that demonstrates this behavior, based on the higher load it has.  They wear all year, and now it is warm....a double whammy...

PP experience, I am clearly not a mechanic...

Best regards,

-a-

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If it doesn't have a healthy click feel to it there isn't much that can be done, I don't believe.  Compare to the other switches/CBs

Before a flight, with the master off, does the switch mechanically work normally?

Some things to consider...  Is something artificially making it get hot?  Like too much current running through it. Has something been added to it's load?  Has anything been rewired like new LED lights in place of the old standard lights?

check the price on the switch/CB after you are done flying for the day...

Private Pilot ideas, not a mechanic or electrician.

Best regards,

-a-

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5 hours ago, Marauder said: If they look like these, they are Klixons.

c5f411710cb0a9930b6d1b13f13e6f57.jpg

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They are this type. So maybe the klixons? Maybe a earlier version 

image.jpeg

Yep, they look like black covered Klixon switches.

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They are bi-metallic thermal circuit breakers. Once the disk inside gets hot, it has to cool before the switch can be reset. It will heat up during normal operation, so turning it off may make it so you cannot reset it.

You can buy new switches all day long if you still have a good plastic cover. 

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5 hours ago, N201MKTurbo said:

They are bi-metallic thermal circuit breakers. Once the disk inside gets hot, it has to cool before the switch can be reset. It will heat up during normal operation, so turning it off may make it so you cannot reset it.

You can buy new switches all day long if you still have a good plastic cover. 

That makes sense. It doesn't take long to cool, it's just another thing to be sure not to switch off when in flight. 

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I used to have problems with my landing light when doing currency night landings. From taxi, takeoff, three landings to a full stop, back taxi between each, then back to the hangar was a long time for that big GE bulb to be lit. Since I switched it for a Whelen Parmetheus, I only turn it off when having the master in for over an hour inside the hangar (like the IFR cert testing). No more heat problems. 

It wouldn't surprise me if the Nav Light breaker was picking up heat from the landing light breaker bolted on beside it.

P.S.--my C has exactly the same switches, but the gear lever is immediately to the left and not a little below them.

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