Is it possible to manually trip the flush circuit breakers?

maduro

maduro

Pre-takeoff checklist
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Maduro
Is it possible to manually trip the flush circuit breakers? The mushroom head ones you can pull but how do you manually trip the flush mount breakers? Thanx.
 
Larry in TN said:
From the title, I thought you were trying to disable the aircraft's lav...

I don't know of any way to trip the CBs that you can't grab and pull.
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Yea.... I did it to get your attention!! lol
 
Larry in TN said:
From the title, I thought you were trying to disable the aircraft's lav...

I don't know of any way to trip the CBs that you can't grab and pull.
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I had electric trim installed on my yoke and I want to be able to turn it off incase of a runaway.
 
maduro said:
Is it possible to manually trip the flush circuit breakers? The mushroom head ones you can pull but how do you manually trip the flush mount breakers? Thanx.
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Nope, and if you're thinking "hmm, maybe I can pop it out with this pointy object...", you'll just gouge up the plastic.
 
maduro said:
Is it possible to manually trip the flush circuit breakers?
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No. Only options are to install trim disconnect switch or replace CB with a resettable type. Or both if the trim motor gets power from two different sources.
 
I remember the avionics shop pointing out to me the new pull out breakers when he flew with me the first flight. I thought they had to be used?
 

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maduro said:
how do you manually trip the flush mount breakers?
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add a push button to power the landing light from the 3 amp trim breaker. It will pop quickly! Or, change the breaker to Klixon like the rest of us have.
 
Let'sgoflying! said:
I can do it, but it involves sparks.
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Oh, no. One has to get sophisticated. Install a switch that grounds the output terminal of the breaker. Sparks are hidden inside the switch. The breaker will pop.

Note to newbies: this is not a serious suggestion. I have popped breakers intentionally for troubleshooting purposes by shorting the output, but people without electrical savvy can do a lot of damage fooling with it.
 
Bell206 said:
No. Only options are to install trim disconnect switch or replace CB with a resettable type. Or both if the trim motor gets power from two different sources.
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The trim circuit breaker on my Beech is of the pullable type, but it will also trip in a runaway if I just grab and hold the trim wheel. In fact, the owner's manual recommends this as the way to handle a runaway (I suspect the plane had a non-pullable breaker when the manual was written). Holding the trim wheel while commanding trim might work on @maduro 's plane to pop the breaker.
 
Half Fast said:
Holding the trim wheel while commanding trim might work on @maduro 's plane to pop the breaker.
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That would depend on whether the cable tension and clutch setting were up to spec. Otherwise, there could be enough slippage that the motor doesn't load up enough to pop the breaker.

Worn cable capstans also have little grip on the cable even at specified tensions.
 
I popped my landing light circuit a few weeks ago. Had not yet put insulating tubing over the knife blade connector to the cowl. Was testing my switches and the connector touched the firewall. No sparks or anything. A 5 amp breaker goes quick, about 1/100th of a second I believe.
 
Bell206 said:
No. Only options are to install trim disconnect switch or replace CB with a resettable type. Or both if the trim motor gets power from two different sources.
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Seems like that would be good design practice. Worst case, turn off the master.
 
I'm having panel work done on my 182. One of the items was moving from the flush mount to the pullable circuit breakers for this exact reason. I bought some used Klixon for like $10 each and since the panel is apart and being newly cut there was no additional installation charges.

If you go this way there are a ton of them in aircraft salvage yards and they're a lot cheaper than what Spruce charges.
 
Supereri said:
If you go this way there are a ton of them in aircraft salvage yards and they're a lot cheaper than what Spruce charges.
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Beware. Old breakers often have oxidized contacts that create resistance and heat, and these breakers are thermal devices that us a bimetal strip that bends and trips the breaker when too much current flows. Oxidized breakers will trip off sooner for no apparent reason.

Nothing lasts forever. It's either rotting or rusting or corroding or oxidizing or drying out and crumbling(plastic and rubber) or drying out and stiffening (lubricants) even if the airplane never flies. Nature is eager to take it all back. I have had to replace switches and breakers due to oxidized contacts. Even had to replace starter and master contactors in a 2300-hour TTSN 172 that was maybe 25 or 30 years old. The starter was lazy due to oxidation of the contacts. A bad breaker that stopped a strobe. Landing light switches that got hot and melted. All oxidation.
 
robin ardoin said:
You haven't made an in promptu field fabricated one yet? I'm Shocked!
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I have a more sophisticated tool that traces the circuit. Plug in a little doodad that sends a signal along the wire. Go to the breaker box and put the detector's tip on the breakers to locate the right one. But that signal spatters all over the box and through the breakers and things get a little confused. That shorting tool would give a definitive answer.
 
Dan Thomas said:
Beware. Old breakers often have oxidized contacts that create resistance and heat, and these breakers are thermal devices that us a bimetal strip that bends and trips the breaker when too much current flows. Oxidized breakers will trip off sooner for no apparent reason.

Nothing lasts forever. It's either rotting or rusting or corroding or oxidizing or drying out and crumbling(plastic and rubber) or drying out and stiffening (lubricants) even if the airplane never flies. Nature is eager to take it all back. I have had to replace switches and breakers due to oxidized contacts. Even had to replace starter and master contactors in a 2300-hour TTSN 172 that was maybe 25 or 30 years old. The starter was lazy due to oxidation of the contacts. A bad breaker that stopped a strobe. Landing light switches that got hot and melted. All oxidation.
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Thanks, that's good feedback.
 
Supereri said:
Thanks, that's good feedback.
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Just to add to the above, while it is a good way to source CBs you need to do your due diligence. There are specs to bench check the breakers plus I usually sacrifice one from the lot and open it up for a check.

I usually stay away from accident aircraft as a donor and stick to weather damaged ones provided the cockpit areas were not exposed the elements. Also look for turbine helicopters as most their breaker panels are easy to cut out and you can sometimes get a volime discount.
 
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