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Systems Question - Resetting Circuit Breakers

Hammer10k

Well-Known Member
Hi all,

T-6B NATOPS discusses resetting circuit breakers with the caution that:

"The pilot should assess the severity of the emergency, equipment lost, and the benefits gained prior to resetting or opening any circuit breaker. If the mission can be continued or the aircraft safely recovered without the affected equipment, the circuit breaker should not be reset."

There aren't possible dangers listed, such as electrical fires or further electrical failures, so I'm not sure how to balance the cost/benefit to resetting circuit breakers. Nearly all the electrical emergency procedures have a "Check - Reset, if open" step. I also have no engineering/electrical background so this is new to me, and I'm hoping to be able to discuss the possible dangers from resets.

Any thoughts?

Thanks!
 
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sickboy

Well-Known Member
pilot
You're entering into the famous "sound judgement" grey areas of NATOPS. You will become very familiar with this further down the road. The second sentence of that caution is the key part to my mind. It's all ORM from there. Electrical fires are certainly a risk to consider.
 

Jim123

DD-214 in hand and I'm gonna party like it's 1998
pilot
Don't read too much into that caution statement. It says everything you really need to know about the question.

Several years ago it was more routine to pull and reset circuit breakers during troubleshooting, but that has gradually fallen out of favor, especially for fuel-related things and the TWA 800 disaster... but I digress.

Again, refer to that caution as a good statement that stands on its own. At least as far as flying the T-6 single pilot, there is almost nothing in that airplane, that could pop its circuit breaker, for which there isn't a backup system or a workaround to safely get it back on the ground.
 

xj220

Will fly for food.
pilot
Contributor
I'm all seriousness, as an SNA your best course of action is the most conservative. If NATOPS says reset then do it, but the T-6 is very safe and redundancy will allow you to get it back. Only go against the book if you have a very, very good reason.

In the P-3 you'd do it all the time. In the P-8 you almost never do it.
 

sevenhelmet

Uh oh...
pilot
Sounds like a great question for an IP during a debrief or ready room discussion.

I'd say as an SNA, you'll nearly always be VFR, so I wouldn't worry too much about resetting breakers unless it's specified by NATOPS. If you really really want to reset one, the guidance I was given a long time ago was that you can reset a breaker once, if it pops again leave it the F alone.
 

Hammer10k

Well-Known Member
Thank you for the replies! Things are clearer now. The discussion item is for avionics failures - specifically a dual IAC failure in IMC. Sound judgement and the caution statement says that this is a scenario where we are resetting the breaker.
 

SynixMan

Professional CCX Wrangler
pilot
Contributor
Thank you for the replies! Things are clearer now. The discussion item is for avionics failures - specifically a dual IAC failure in IMC. Sound judgement and the caution statement says that this is a scenario where we are resetting the breaker.
If it's already having issues, sometimes a hard reset may be best option. For example, TCAS will shit itself on occasion and the only way to reset it is via the CB or the avionics master. Easy answer on which one makes more sense.
 

Jim123

DD-214 in hand and I'm gonna party like it's 1998
pilot
and be a man when you reset those puppies! HOLD the CB in - that's why god gave you Nomex gloves. Don't mind the heat.
Funny you should mention that...

The circuit breakers the T-6 has are a tiny fraction of an inch shorter take most aviation c/bs. A surprising number of students have trouble pulling them (it's a common thing to pull the TCAS c/b and reset it when the TCAS just randomly decides not to work). You have to take your gloves off and wedge the sides of your fingertip and thumbtip in there. Kids with fat fingers and poor dexterity have a lot of trouble figuring that out... Part of it is a generational thing too- a lot of these damn millennials never had shop class or learned to change the oil on their own car so they never learned to fix stuff with their own two hands. (Being half facetious, half serious here... they can program a magenta line in the FMS like a boss.)

But in all fairness the breakers really do sit just a bit too flush on the panels. Fortunately, there is only one breaker that you'd need to pull in a timely fashion and that one has a plastic collar to make it easier to find and grip.
 

ChuckM

Well-Known Member
pilot
Just remember, whatever you do, don't hold CB's in! They should keep doing thier job and popping. My rule is two resets in one flight, with time to cool down in between. Pops a third time, it's dead to me. That's where my comfort level is at after 9 yrs. in cockpit. I can count popped circuit breakers on my hands and toes. Doesn't happen often.

Manipulating a CB for the purposes of a "hard reset" should not be considered resetting in the manner above. That is common place an akin to flipping a light switch.

I grew up in a legacy aircraft with analogue equipment, tranistors etc., and now in an all glass cockpit I find myself using CBs for troubleshooting far more often.
 

HAL Pilot

Well-Known Member
None
Contributor
Just remember, whatever you do, don't hold CB's in! They should keep doing thier job and popping. My rule is two resets in one flight, with time to cool down in between. Pops a third time, it's dead to me. That's where my comfort level is at after 9 yrs. in cockpit. I can count popped circuit breakers on my hands and toes. Doesn't happen often.
2 resets? Interesting. Most airlines allow a max of 1 reset if at all.
 

Pags

Well-Known Member
pilot
And here's where "sound judgement" is substituted for "community gouge" and "that's what my HAC said."

Think about it: CBs are designed to protect expensive electronic equipment from being zapped from too much current. If the CBs popped it's because the system is trying to protect itself. If you reset that CB you're allowing that initial failure mode to occur again. If your box gets too much current it could release magic smoke or it could catch on fire resulting in some/fumes in the cockpit or an electrical fire of unknown origin; two things you don't really want to have happen in an airplane that you're strapped in to*. Holding in a popped CB only forces a failure mode and further increases the odds of equipment failure and fire. The sound judgement comes in as to whether the possible risk of fire is worth it over something worse like a failed gyro in the goo at night. In most cases you're better off following the steps in the EPs and doing extensive troubleshooting of CBs on the ground*.


*as someone on this forum once said: the best place to watch an airplane burn is outside of it, on the ground, at a safe distance. At that point the only thing you need to worry about is whether you left your car keys in the plane.
 
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