PA-28 Nav Light Circuit Breaker Popped?

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techflight

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techflight
Today when flying my Piper Archer II, all the lights were turned on (landing, anti-collision, strobe, and recog) except for the nav lights. A second or two after I turned the dial to activate the nav lights, the nav light circuit breaker popped and the avionics screens briefly changed brightness. I turned off the nav lights, put the circuit breaker back in, and tried turning on the nav lights again but the same issue occurred. I left the nav lights off for the rest of the flight. Upon landing and engine shutdown, I tried testing the nav lights again and they worked fine, just as they did during pre-flight including with all the avionics and other lights still on. There's been no super recent work done to the airplane.

Any ideas? Thanks for any help / insight here!
 
Which type of Nav Lights do you have? Traditional or LED?
Measure the actual current draw from the Nav Lights. What is the rated size of the breaker. Compare the two values. If the two values are close, swap the breaker for a new breaker. See if the issue happens again.
 
Was this a long flight? (3+ hrs?)

When I got my airplane (Arrow), I would turn everything ON and after extended flights (3.5/4+ hrs), a breaker would start to pop.

My mechanic said, the airplane is old, don’t run everything at once and we did get a new Plane Power alternator. With that, haven’t had any issues since.

When you are running everything, where was your Amp meter at? I think to keep mine around half, and if you are running it more, then consider if you can make some of your lights LED (which use less power and run cooler). I am more conscious on light usage, my NAVs are always ON as they are connected to my adsb, but I only use the landing light for takeoffs and landings (if at night), and I rarely use the strobes (unless I want to be seen by traffic - my beacon is LED and very bright already).
 
I've had two circuit breakers go bad. No issue with the item, just the breaker.
 
techflight said:
the avionics screens briefly changed brightness.
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The fact you noted an electrical change in a separate system at the same time as the CB popping, you may want to troubleshoot a bit more to ensure the CB wasnt simply doing its job. If you're comfortable using a schematic and VOM/test light might be able to give you a couple checks to the system before you change parts or a hidden issue causes you another a more serious issue.
 
Bell206 said:
The fact you noted an electrical change in a separate system at the same time as the CB popping, you may want to troubleshoot a bit more to ensure the CB wasnt simply doing its job.
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:yeahthat:
 
I would change out the circuit breaker first and see if that fixes the problem. If not, I would try to use an ohm meter to identify which wing had the short and inspect wiring. On the nav circuitry, there is a single wire going to the nav lights and there is a ground wire at the wing tip. Very simple circuit.
 
Cherokee wings have rubber grommets where the wire passes through the ribs.

They tend to disintegrate and the wire is then dancing on the sharp edge of a

rib hole.

This can give you an intermittent short circuit.

Another wonderful intermittent electrical issue.


Well worth checking when tanks are out or tips off.
 
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Magman said:
Cherokee wings have rubber grommets where the wire passes through the ribs.

They tend to disintegrate and the wire is then dancing on the sharp edge of a

rib hole.

This can give you an intermittent short circuit.

Another wonderful intermittent electrical issue.
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That's a great suggestion. On my Warrior, I picked up a bunch of the nylon cable guards and put those around every hole where there are electrical wires. I don't know what you call these but they have teeth on both sides that keep them from coming out of the hole. You cut them to length to fit the hole. These work well for holes over an inch diameter.
 
Thanks for the suggestions everyone. The problem is a bit less ambiguous now-- I went down to the airport this morning and during the pre-flight almost immediately after turning on the nav lights the breaker popped out this time. The nav lights are required to be on for the anti-collision and strobe lights to activate (it's all one LED unit on each of the wing tips). Therefore the plane is grounded and I brought it over to an avionics shop, and they suspect it's a short perhaps in one of the light units.
 
Check the wire going to the tail nav light. Piper did a poor job at securing that wire at each bulkhead.
 
I dimly recall had a junction point under the rear seats of a 140.

The SM may not specify a location in the schematic.

“Isolate and conquer!”
 
techflight said:
...they suspect it's a short perhaps in one of the light units.
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As others have mentioned, unless they replaced all the original wires and through-hole grommets when the LED lights were installed, my first suspicion would be frayed insulation due to rubbing against structure somewhere and shorting to that structure, rather than a failure of one of the LED lights.
 
kshaw said:
That's a great suggestion. On my Warrior, I picked up a bunch of the nylon cable guards and put those around every hole where there are electrical wires. I don't know what you call these but they have teeth on both sides that keep them from coming out of the hole. You cut them to length to fit the hole. These work well for holes over an inch diameter.
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The holes are a fixed diameter. How can "You cut them to length to fit the hole." A link might clarify.
 
kshaw said:
I don't know what you call these
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The informal name is railroad track. The only negative side to them is on the install side as they have a tendency to pop out if not secured properly vs a rubber gromment
Domenick said:
How can "You cut them to length to fit the hole." A link might clarify.
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The easiest way is to take a length and temp install in opening. Where it overlaps add two "teeth" and cut. Might have to adjust the 2 up or down to get tight fit depending on brand. Then secure track with glue or other product to prevent it from falling out.
 
Bell206 said:
The informal name is railroad track. The only negative side to them is on the install side as they have a tendency to pop out if not secured properly vs a rubber gromment

The easiest way is to take a length and temp install in opening. Where it overlaps add two "teeth" and cut. Might have to adjust the 2 up or down to get tight fit depending on brand. Then secure track with glue or other product to prevent it from falling out.
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I did't think of using glue but mine have stayed in so far. Yes, just trial and error to get a good fit.
 
kshaw said:
I did't think of using glue
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At least a couple dabs of super glue would be highly recommeded. Once the track pops out it can over looked on subsequent checks as it leaves no telltales it was once there like an old grommet does. Its the reason I use a colored glue to secure the tracks so even if they pop loose the glue residue serves as a clue something may have been there.
 
Thanks everyone, it did end up being a problem with a wire rubbing against the structure. Adding insulation resolved the issue!
 
Murph said:
Wire size determines breaker size doesn't it?
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I was not posting a general rule for electricians to follow.

This was specific advice for an old aircraft with an old circuit breaker with old traditional Nav lights.

Which ended up being irrelevant as the lighting had been replaced with low power LED lights.
 
focal_plane said:
Another choice: 3M 1300L / Scotchweld adhesive
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I don't like RTV around any engine or fuel or oil system, but for holding stuff like this it would work real well. Getting at some of these is a pain, and brushing glue onto it is a similar hassle. A gob of RTV on a fingertip, worked into the installed strip in two or three places, would stick it there forever. The 1300L dries out and peels with age, and the heat inside a wing in the sun would age it faster. It's just a good grade of contact cement.
 
Permatex Ultra Black Gasket maker

From their site:

Maximum Oil Resistance RTV Silicone Gasket Maker; Black; 3.35 Ounce Tube; OEM specified. For dealership warranty requirements, ensures extended drivetrain warranty compliance. Fast-curing formula. Sensor safe, low odor, noncorrosive. Meets performance specs of OE silicone gaskets. Retains high flexibility, oil resistance properties through use of a patented adhesion system. Temperature range -65 to 500 Fahrenheit (-54C to 260C) intermittent; resists auto and shop fluids and vibration.

I use it to retain an oil seal in a pretty hostile environment. Don't know if it is plane approved...L
 
Murph said:
I use it to retain an oil seal in a pretty hostile environment. Don't know if it is plane approved...L
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The only approved adhesives and sealants are listed in Service Letters published by Lycoming and Continental. IIRC, silicones shows up in only one of those, and in only one or two specific applications, and only one or two specific sealants are approved, not just any silicone.

If it is used, it has to be used very sparingly. It tends to extrude when the parts are assembled, and if it extrudes to the inside, it sets and eventually breaks off and can plug oil or fuel passages and cause engine failure. It has happened many times. Mechanics are far too fond of the stuff.
 
the application I was referring to is in a Kawasaki...:D
 
Great for sealing afterburners too!
 
techflight said:
Thanks everyone, it did end up being a problem with a wire rubbing against the structure. Adding insulation resolved the issue!
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Glad you found the problem! Electrical gremlins are never fun.
 
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