Anti-Collision Switch

[usafhaynes1]

I've just purchased an IFR certified Mooney this past weekend and flew it home getting some good practice filing IFR routes.  The first flight was a night flight and I had no issues with either the rotating beacon, anti-collision or landing lights.

This morning, I took off from 75FL, VFR, picked up an IFR clearance enroute, had all my proper lights on and noticed later on that my anti-collision light switch was off.  I wasn't sure if I'd bumped it while turning off the landing light after takeoff so I switched it back on.  It did not immediately pop off and the sun did start to rise so I didn't notice that it had, again, switched off.  On landing at KMEI, I noticed the switch in the off position and turned it back on only to have it pop off about 60 seconds later.

 

My question to all, is this a possible switch going bad or a short?  My friend was standing midfield on my takeoff and informed me that the lights were all properly working as I got airborne.  Thoughts?

I have the alternator and it is always at 0, only momentarily going negative when I first switch on various electrical requirements, then it goes back to 0, so it's charging.

 

Also, while in troubleshooting mode, I have an STEC-30 that has two switches and two buttons.  1st switch is on/off, 2nd is keep alive, 1st button is heading (gyro heading bug) and 2nd is alt hold.  The system is currently inop.  Anyone have any ideas of what the most common failures of the autopilot system are?  I cannot find any decent manual on the STEC-30 that was installed in 1998.  The website only seems to report the newer versions.

 

Thanks in advance for any advice.

 

[Marauder]

First, the lights... If you have a rocker style switch like these: Then you have an integral circuit breaker light switch controlling the lights. The reason they pop is because just like a regular push pull circuit breaker, that is what they do when a short or excessive draw exists. Since they don't pop immediately, either you are experiencing an intermittent short or an electronic component overheat. I would begin with the wiring, ballast and then work my way back to the breaker switch. As for the AP, there should be an AP master switch for your STEC as well as a breaker. The on/off switch is a straight on/off. you should be able to put an ohm meter on it and see if is working correctly. I don't understand what you mean by the second switch function. Can you explain? The 1998 version is not different from the current model. Any STEC manual for the 30 will give you what you need for troubleshooting.

[Marauder]

Sorry, tried to copy a link to the STEC 30 manuals. Can't for some reason, I would just google for one.

[mikesalman]

It's funny because I am having the exact same problem with my position lights. I only have 21 hours on my 68F and all vfr day. I noticed my toggle switch turned off in flight, I thought maybe it was caused by turbulence. 3 days ago on a flight from M01 to Petit Jean in Arkansas and back I played with it a couple of times. I would find it off and turn it back on then it stopped turning on. I went to the airport today put a charge on the battery and flipped the switch on. 3 minutes later it popped off. I called Laser for a replacement thinking maybe a weak switch $40-$60 was my guess and a lot easier than trouble shooting if it worked. Well that 5 amp toggle switch was over $140 plus shipping, tomorrow I will be trouble shooting with my A&P. Good luck

[usafhaynes1]

I don't have the rocker switch, it's the old style switch.  I'll check the wiring. 

 

As far as the STEC, the two toggles are autopilot on/off and keep alive on/off.  I've no idea what the keep alive toggle does.  I'll look for the breaker.

Thanks for the input.

[tony]

I have the older klixon switch that are both a switch and circuit breaker like these http://www.sensata.com/klixon/circuit-breaker-aircraft-7270.htm

 

These switches are bimetallic devices and generate heat as current flows through them.  So when there is too much current draw they generate heat and pop.  As they age they get corrosion inside and the internal resistance goes up.  That higher than normal resistance also generates heat. So old corroded switches will pop even when there is not an excessive current in the circuit.  I've had to replaced a few already and they aren't cheap.  about a 100 bucks a switch. 

[Marauder]

I don't have the rocker switch, it's the old style switch. I'll check the wiring. As far as the STEC, the two toggles are autopilot on/off and keep alive on/off. I've no idea what the keep alive toggle does. I'll look for the breaker. Thanks for the input.

It sounds like from Mike's comments, the older toggle switch type also contain a circuit breaker. I would look for a short if the toggle breaker is good. Let us know what the "keep alive" switch does. Real mystery.

[mikesalman]

It does contain a Klixon built in circuit breaker in the switch. I checked two places 1) $140. 2nd) $145.

[triple8s]

Are your NAV light switches to the left of where tube goes into the panel? (the tube the yoke is connected to) My old "C" had the switches there and my Boost pump switch started turning itself off. After some investigation I figured out that the instrument panel shock mounts were saggy and any little increase in "G's" or sudden vibration or movement in the instrument panel would touch the switch enough to cause it to turn off.

[1964-M20E]

I have the STEC 30 with ALT hold in my plane. Not long after I had it the selector knob on the STEC 30 controller head ( the round knob on the lower left hand side) stopped working. The unit would power up but I could not select any of the modes ST, HD, LO or HI. It was a relatively easy fix for the avionics shop about $400. There is a small connector inside that has a tendency to break the shop told me the new one was better than the old one.  Once the AP is on you gently push in on the round selector knob to change the mode sometimes I have to gently pull it out as well.  I think it is supposed to spring back out on its own though.  There is a way you can wire an external selector switch as well.  One day I will get an external selector switch wired into my system.

[carusoam]

Switch out the circuit breaker/switch combo. They are known to lose their ability to carry current over time...

Then troubleshoot to determine if there is a serious challenge...

Whelen makes a modern anti-collision light...

You don't have the motorized set of bright DC bulbs do you??? Clean and grease the moving parts!!!

Best regards,

-a-

[usafhaynes1]

Yesterday quick .5 flight to a neighbor city and I turned on lights. Again, after about 10 minutes, the anti-collision switch popped off. I switched off the rotating beacon and flipped on the collision switch and it never popped off. Is this a switch issue or a load issue? It only pops off if I have both beacon and collision switch on.

[47U]

I guess I'm curious as to terminology.  My '63C has five switches, left to right they are 1) fuel pump, 2) pitot heat, 3) anti colision (rotating beacon replaced with a strobe), 4) navigation lights, and 5) landing light.  I'm confused by you having separate anit collision and beacon switches.

 

My landing light Klixon got weak, and felt weak when actuated.  It got to where it wouldn't hold the current and would trip leaving me taxiing in the dark.  It would not immediately reset after tripping.  In a few minutes, it would hold current for another two or three minutes.  Lasar fixed me up and it was north of $100.  The original was made by Texas Instruments, I think.  The new one was made in Mexico.  The Klixon part numbers are dependent upon the current rating.

[Marauder]

I guess I'm curious as to terminology. My '63C has five switches, left to right they are 1) fuel pump, 2) pitot heat, 3) anti colision (rotating beacon replaced with a strobe), 4) navigation lights, and 5) landing light. I'm confused by you having separate anit collision and beacon switches. My landing light Klixon got weak, and felt weak when actuated. It got to where it wouldn't hold the current and would trip leaving me taxiing in the dark. It would not immediately reset after tripping. In a few minutes, it would hold current for another two or three minutes. Lasar fixed me up and it was north of $100. The original was made by Texas Instruments, I think. The new one was made in Mexico. The Klixon part numbers are dependent upon the current rating.

I too am confused by his terminology. Could it be that he has wing tip strobes as well as the beacon and there was a switch added?

[usafhaynes1]

My switches from left to right are boost pump, auto pilot, keep alive (?), pitot heat, rotating beacon, anti collision (wingtip lights), landing light.

The only switch that has a problem is the anti collision switch unless it is on by itself.

[carusoam]

The keep alive switch is unique...

I assume that is powering some electronic memory device, that could drain a battery over time...?

If it is a device to keep the pilot alive, see your doctor before switching it out...?

Does the motorized, anti collision light, stil rotate? You will probably hear it whining in the radios if it does. If it has stopped, the background noise is lessened...

I think the grease used is similar to the trim system. It gets hardened over time and helps jam up the works...

Either way it is a good reason to look up the Whelen unit. It fits in the same hole. Either top or bottom. Nice way to get a xenon flash if you don't have one...

My C is gone, but I think I still have the rotating beacon on a shelf...

Best regards,

-a-

[Marauder]

I forgot about the motor in that beacon. If that motor is binding, I wonder if it is not causing more current draw. I converted mine over to a strobe years ago.

[usafhaynes1]

The rotating beacon is still turning.  I definitely hear it when I turn on the switch when at 1000 rpm.  Once I apply throttle, the interference in my headset quits.  I'm still looking for theories on what is causing the anti-collision lights to pop off when all lights are on versus staying on when that is the only active switch.  Is it a current load issue?  If so, why does the switch have no issue if the beacon switch is off?  Ideas?

My current theory on the keep alive switch is that is has something to do with pulling current directly from the battery (my buddy's F model had a keep alive switch on it as well).

[47U]

Generator or alternator?  What's the voltage regulator set at?  (CAUTION: wild speculation.)  If the beacon motor is draggy it's drawing more current.  It might be enough voltage drop that the voltage regulator kicks up to charging voltage thereby tripping a weak anticollision switch.  The anitcollision switch by itself doesn't draw enough current for the same voltage drop as when the beacon is also on.

What does the anticollision switch feel like when you actuate it?  Does it feel like the other (less used) switches?  My landing light switch definitely felt "soft."  The new one was very crisp.

[usafhaynes1]

Alternator, switch feels solid.

[47U]

Are you running strobes on the wing tips or are you stock? The switch is rated at 5 amps, if I remember. If the installation is per spec, check connections, grounds, even pull the bulbs (if stock) out of the sockets and make sure the contacts are clean and corrosion free.

Lying under the panel is always fun. I'm guessing that if all is in order after inspection, if the switch is original, it's worn internally and won't hold the load.

[usafhaynes1]

I flew to tn last night and home this morning. Strangely, I ran all lights without issue yesterday and this morning while flying ifr through clouds. I'll keep an eye on it.

[FlyingAggie]

Does anyone know the make and model of the lower switch? The upper one is a Klixon model 20TC used in the late 70's Mooney's. The lower one is used in later Mooney's. I thought it was also a Klixon, but can't find anything that looks like it.

[Marauder]

Does anyone know the make and model of the lower switch? The upper one is a Klixon model 20TC used in the late 70's Mooney's. The lower one is used in later Mooney's. I thought it was also a Klixon, but can't find anything that looks like it.

That's my picture! Where did you find it? The only identification on the switch are; The letters E-T-A, the word Germany. I bought a set of them thinking they were the Klixon 20TC ones.

[Marauder]

I just found a patent number on one of them. 4148002. Are you looking for these switches?