Comments on: CBs – No reset!

By: Terry Scott

Terry Scott — Thu, 12 Apr 2012 01:35:59 +0000

This subject came up and we all agreed CBs are not switches and they don’t work like switches so simulating things by turning then off then on is breaking two big rules. Its not a switch so they are being improperly used and resetting them just because you pulled it with out coming to a full stop landing is the other.

By: John LeNard

John LeNard — Sat, 02 May 2009 20:40:20 +0000

The rule as I learned it was to turn off all devices on the popped circuit breaker and only then should you reset it. Then you can turn on each device, one at a time, with a good wait between each. Then the one which popped the circuit breaker again was the curlpit.
Knowing the electrical circuit in today’s airplanes is critical to safe flying.

By: Bruce Liddel

Bruce Liddel — Fri, 01 May 2009 19:51:29 +0000

Obviously, if there is a CB for each individual device on your AC, then yes, of course, I agree, leave the popped breaker alone, especially if you smelled smoke.

Suppose you are in near IMC (like at night over nowhere under a moonless overcast) in some un-restored classic where some idiot retrofitted a current-hungry device onto the same CB as your turn coordinator and /or pitot heat, and maybe you don’t have an engine-driven vacuum pump. You don’t smell anything, but your breaker pops just as as the power-hungry device (or turn coordinator) indicates a loss of electrical. Yes, I know, you shouldn’t have been there in the first place. Still, it would be mighty tempting to switch off the other device or devices, wait a minute, and try again at least once to restore only the pitot heat or turn coordinator, especially if manually pulling the breaker again (at the first sensation of any odor) is an option. I guess in this scenario the turn coordinator or pitot heat would be considered “flight critical”?

Not all aircraft are alike – some have stupid stuff done to them. All situations are not alike. One simple rule like “no reset” can’t address every single possibility. As pilot, you’ve got to know your aircraft inside and out, and manage the risks accordingly.

By: John Taylor

John Taylor — Fri, 01 May 2009 17:11:46 +0000

Bruce: You might mention that aircraft with checklists will have procedures wherein CB may be reset, but only when the checklist allows. The Falcon 2000 which I fly is one such airplane. We don’t pull’em, we don’t set’em.

By: Bruce Landsberg

Bruce Landsberg — Fri, 01 May 2009 14:56:42 +0000

Larry ….

One of us is confused – the NTSB’s and ASF’s recommendation is to NOT reset unless the item is flight critical. We’ll leave it to the pilot to determine flight critical but I would err on the side of extreme caution – unless it’s something that will definetly cause a major problem we don’t recommend rest.

I think we are in raging agreement

By: Larry Anderson

Larry Anderson — Fri, 01 May 2009 12:58:38 +0000

Bruce,

Your advice to not reset CBs seems to conflict with the advice given in In-Flight Electrical Fires. I agree with you. It’s dangerous to second-guess the CB. If the tripped CB prevented a fire, you have just excaped a bullet, No sense in playing Russian Roulet. By-the-way, I am a CFII and an electrical engineer.

Larry Anderson