NAV light switch

[MtPleasantFlyer]

I have a 5 Amp breaker switch that turns on my Red/ Green/ White NAV lights.  On a recent night flight, I noticed my switch was off after previously being on.  I turned it back on and after around 5 minutes it was back off. Does anyone have suggestions on how I can solve this problem? I'm assuming its not a short, since the switch doesn't flip immediately.Are the internal connections of the switch failing? Could it be the bulbs drawing to much amperage after getting hot? Any help?

[carusoam]

Probably like the landing light breaker/switch.

They wear with time and break earlier than expected.

A new switch will feel different than a warn one...

Make sense?

-a-

[trey]

Several of the switches in my M20C were doing the same thing. I replaced them with new switches and the problem is solved.

 

The Klixon breaker switches are kind of expensive for what they are. The best source I've found for them is a company called Peerless Electronics. They seem to be $30 or $40 less expensive per switch than others. See links below:

 

http://www.peerlesselectronics.com/store/search.php?search_query=7270-5-5

http://www.peerlesselectronics.com/store/products/7270%252d5%252d5.html

[N201MKTurbo]

Or you could replace your nav lights with LED lights. It would reduce the current draw considerably and the old tired breaker would not trip.

[MtPleasantFlyer]

Would something like this work?

http://www.aircraftspruce.com/catalog/elpages/pbcircuitbrkr2.php

[Glenn]

It will probably make sense to match the existing switches.  If they are the same as my 67F, they all receive power from a rigid buss bar.  Look behind your panel and you will see the difficulty that a switch of a different physical configuration will cause.

[moodychief]

I believe it is the same 5A switch as used for the fuel pump. I bought my replacement 5A switch for the fuel pump from Aircraft Spruce.

[MtPleasantFlyer]

I believe it is the same 5A switch as used for the fuel pump. I bought my replacement 5A switch for the fuel pump from Aircraft Spruce.

Do you remember the part number? I have been looking at the difference between the Peerlesse, Klixon, and Tyco. They all seem to be very very close in dimensions.  

[Gilt]

Had the same problem with the NAV light switch...replaced NAV lights with LED's . Problem Solved.

[moodychief]

Aircraft Spruce 11-03936. The one I received was labeled TYCO but the defective one was a Siemens.

TYCO acquired Siemens in 2000.

[DaveL]

Is the switch, when on, close to the shock mounted panel? My landing light switch does the same thing, and it appears to be sagging isolaters letting the dash knock the switch off.

[NotarPilot]

If you have a 12V and are considering LEDs, here's what I got from Aircraft Spruce:

LED 7512-12V GREEN LAMP Part# 11-07745

LED 7512-12V RED LAMP Part# 11-07744

LED 75TPL -12V TAIL POSITION LAMP Part# 11-07748

They're not exactly cheap apx. $34 USD each, but probably worth the investment

(Same with the WHEELEN PAR 46 Landing Light 01- 0790612-10 Part# 11-09523, $289 USD, not cheap, but PMA'd and probably worth the investment)

 

I hate to be a Debbie Downer but I bought these for my plane and found out they were not legal as they are not PMA'd.  I subsequently returned them for a refund. Purchase at your own risk.

[Mooneymite]

The switch kicks off when resistance reaches a certain point. While the chances are good that the switch is going bad, you might try cleaning all the electrical connection points including the bulb bases and sockets. Cumulative corrosion may be the culprit.

Low tech, low cost solution.

[1964-M20E]

Would something like this work?

http://www.aircraftspruce.com/catalog/elpages/pbcircuitbrkr2.php

Before I’d spend $150 on a single switch I’d get 4 at $25 top $45 each (PH,NAV lgt, land lgt, & strobe lgt) of these and replace them all so size differences will not matter.  That way in the future if you ever have any problems with these there are easily and readily obtainable.  You could even replace the one on your fuel pump while you are at it.

[jkhirsch]

I have noticed this issue on a couple occasions, it's not a fix but I have observed that if I hold the switch in the on position for a few seconds it will stay on.

[treebobboy]

I would like to point out that these switches are really circuit breakers and you DO NOT reset a CB by holding it in.  If you hold in a bad CB, you are going to cause it to overheat and this could lead to a fire.  Fire not good in airplanes!

[Monticello Flying Club]

I had this same problem.  Notar is correct, the Tyco are not PMA'd, use at your own risk.  I would hate to be blamed by the insurance company for a fire in the cockpit (or anything else they decide to link to the switch) over $120.  I also replaced my landing light with an LED hoping like N201MKTurbo said it would make a difference.  Made no difference.  If the switch feels a lot looser than the other switches, it is a bad switch.  You should be able to feel a difference in the switch.

[MtPleasantFlyer]

I had this same problem.  Notar is correct, the Tyco are not PMA'd, use at your own risk.  I would hate to be blamed by the insurance company for a fire in the cockpit (or anything else they decide to link to the switch) over $120.  I also replaced my landing light with an LED hoping like N201MKTurbo said it would make a difference.  Made no difference.  If the switch feels a lot looser than the other switches, it is a bad switch.  You should be able to feel a difference in the switch.

 

Not sure what you mean by the Tyco not being PMA'd. Notar is talking about the LED's which are not. Are you talking about the Tyco circuit breaker? I beleive they are PMA'd as they are listed as original replacment for Cessna, Beach, and piper aircraft.

[MtPleasantFlyer]

Aircraft Spruce 11-03936. The one I received was labeled TYCO but the defective one was a Siemens.

TYCO acquired Siemens in 2000.

Did it fit properly to the buss bar? I'm getting conflicting info on the size to use.

[N601RX]

If you currently have Klixon, the Tyco will not mount directly to the bus bar. The Tyco is deeper. Someone had put a Tyco landing light switch on my plane a long time ago and had to cut the bus bar off and use a jumper wire to supply power to the Breaker.  Bus bars will also corrode over time and may need to be cleaned or replaced. Spruce sells mil spec predrilled busbars. If I remember correctly the Klixon switches are manufactured to a mil spec, not a PMA.

[moodychief]

I pulled my old switch and searched for the compatible replacement before ordering. I have a 63 C model. It may have a different setup.

[larryb]

Speaking of switches, has anybody installed a split master switch, with independent control of the alternator field? I would like one for my plane.

[Stefanovm]

I used an STC'd landing light to H3 quartz-iodine bulb, Stan Protigal, ECLIPSE AVIATION, INC., http://www.scn.org/~bk269/eclipse/. Bulbs are inexpensive at auto store, but the STC and parts were $175. "The H3 bulb is commercially available, and doesn't have to say "airplane" on it!" My breaker tripping went away. The 20 amp circuit was NOT drawing 20 amps and now is drawing less than 5, lowest my meter could read. It also produces a better landing light. Be careful, the lamp assembly front lens developed a crack as it fit in the cowl hole too tightly, I believe. My IA said no reason to panic, and quickly replace, if I did not notice a detriment to the light performance. I now use a lot of the time for ID and like the ad says the controllers do appreciate it.

 

Too bad the LED position are not PMA'd. I may try replaceing one anyway as the switch replacement might be more than I want to do and the next annual is 10 months away. The tripping was very inconvenient on last night's longer than usual night flight. I usually only get currency time, but made a 1.5 hour night trip yesterday. I have been puting up with a breaer trip or two durring currency flights.

[Stefanovm]

The switch kicks off when resistance reaches a certain point. While the chances are good that the switch is going bad, you might try cleaning all the electrical connection points including the bulb bases and sockets. Cumulative corrosion may be the culprit.

Low tech, low cost solution.

I will not disagree with cleaning connections, as that is always a good troubleshooting start. However Ohm's Law equation indicates that under a limited voltage as a circuit's resistance increases, the amperage decreases, V(voltage)=I(current) times R(resistance). The breaker is detecting amps using a resistive element for heating inside the device not measuring the circuit resistance. Excessive circuit resistance would lower the actual amps being drawn, at the constant voltage to which an aircraft circuit is limited, and could not be the direct cause of tripping. A dirty connection going to ground would lower the circuit resistance, so cleaning is still good, as it could cause tripping.

 

I am sure that my case is a weakening breaker switch. Even though the Military Specification says 5,000 cycles are available, the 1965 vintage can take its toll on such data. A copy can be downloaded at http://www.everyspec.com/MS-Specs/MS2/MS24000-MS24999/MS24509K_39553/. My engineering experience also has shown that using a breaker as a switch is not the best design or practice. Again, 1965 technology, space saving desires, and sales techniques along with parts obsolescence gives us Mooney owner’s a maintenance challenge.

[carusoam]

Reviewing a few things that come from this discussion...

1) CB switches fail over decades. No matter what the spec sheet indicates the number cycles can be.

2) higher load CBs (landing light) fail after about 40 years, lower load CBs last a little longer...

3) the instrument panel sag on an M20C will aid in turning off a CB. Note the space (or lack of space) allowed between the panel and the switch while it is in the up position.

4) LED lights can lower the load on an aging circuit.

5) switching out CBs with anything other than like for like (identical but from different manufacturer) is asking for additional trouble.

Now that you have identified the challenge, why not go to your local mechanic and ask him to help you identify the proper replacement?

Make sure the CB is on the list of 11 or 13 things a pilot is allowed to do.

The length and depth of this thread would make me want to have someone overlook what I was doing...

I'm only a PP, but enjoy working with a mechanic on such detailed swaps.

I am a CB (I joined a club of CBs) and I have changed my own CBs during owner assisted annuals.

Best regards,

-a-