Best not to push in the CB when there is smoke

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pelmet
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Best not to push in the CB when there is smoke

#1 Post by pelmet » Wed Oct 04, 2017 3:29 pm

C-FRMV, a Beech King Air BE20 aircraft operated by Keewatin Air under KEW202, was conducting a medevac flight from Lourdes-de-Blanc-Sablon, QC (CYBX) to Sept-Iles, QC (CYZV) with 4 passengers and 2 crew members on board. Shortly after departure from CYBX, the crew
noticed a burning smell in the cockpit, followed by the flight nurse reporting that traces of smoke could be seen in the cabin. The source of smoke was identified as coming from under the middle seat area in the cabin. The crew initiated a return to CYBX, and switched the medical inverter to OFF after which the smoke appeared to dissipate. As the aircraft was preparing to land at CYBX, as the crew selected flaps to approach, the flap motor circuit breaker popped. The circuit breaker was reset successfully and the aircraft landed without further event. While taxiing back to the terminal, the flap motor circuit breaker popped a second time when the flaps were selected to the up position. The crew did not reset the circuit breaker.

After investigation, the operator’s maintenance found that the flap travel limit switch cam assembly had cracked, allowing the flap to bottom out within the flap track, just before the travel limit switch being met. This allowed the flap motor to run continuously to hold the flaps in position versus the gearbox holding the flaps in position. Flap travel limit switch cam assembly was changed and, as a precautionary measure, flap motor and gearbox were also changed. The aircraft tested serviceable and was returned to service.
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Re: Best not to push in the CB when there is smoke

#2 Post by dogfood » Thu Oct 05, 2017 4:56 am

Since when do they do medivac in Quebec
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Re: Best not to push in the CB when there is smoke

#3 Post by Jet Jockey » Thu Oct 05, 2017 4:58 am

dogfood wrote:Since when do they do medivac in Quebec
I hope you are being sarcastic.
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Re: Best not to push in the CB when there is smoke

#4 Post by dogfood » Thu Oct 05, 2017 6:59 am

Not at all thought they were nunavut only...
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Re: Best not to push in the CB when there is smoke

#5 Post by golden hawk » Thu Oct 05, 2017 2:11 pm

When is it a good time to reset a popped circuit breaker?
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Re: Best not to push in the CB when there is smoke

#6 Post by av8ts » Fri Oct 06, 2017 7:27 am

golden hawk wrote:When is it a good time to reset a popped circuit breaker?
On the ground when advised to by maintenance one time
Never in the air
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Last edited by av8ts on Sun Oct 08, 2017 6:08 am, edited 1 time in total.

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Re: Best not to push in the CB when there is smoke

#7 Post by Meatservo » Fri Oct 06, 2017 8:58 am

Incorrect. It depends on the breaker. Some should never be reset, some can be reset once. You follow the instructions in the QRH/abnormal or emergency checklist for your aircraft type.
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Re: Best not to push in the CB when there is smoke

#8 Post by xsbank » Fri Oct 06, 2017 9:31 am

Hey Meat, a much better answer would be to delete your first two sentences, follow the QRH.

In this example this crew likely did not follow the smoke in the cabin procedure, they made one up. They are lucky. If I was the CP they would be washing lavatories for a week.
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Re: Best not to push in the CB when there is smoke

#9 Post by bald seagull » Sat Oct 07, 2017 10:36 pm

https://www.tc.gc.ca/eng/civilaviation/ ... 1-1801.htm

As always....Transport Canada knows best!
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Re: Best not to push in the CB when there is smoke

#10 Post by av8ts » Sun Oct 08, 2017 6:11 am

Meatservo wrote:Incorrect. It depends on the breaker. Some should never be reset, some can be reset once. You follow the instructions in the QRH/abnormal or emergency checklist for your aircraft type.
Incorrect

My QRH says never in the air

Company policy is ok to reset on ground when advised by maintenance
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Re: Best not to push in the CB when there is smoke

#11 Post by Meatservo » Sun Oct 08, 2017 11:13 pm

av8ts wrote:
Meatservo wrote:Incorrect. It depends on the breaker. Some should never be reset, some can be reset once. You follow the instructions in the QRH/abnormal or emergency checklist for your aircraft type.
Incorrect

My QRH says never in the air

Company policy is ok to reset on ground when advised by maintenance
Maybe yours does. There are lots of aircraft models in which certain breakers can be reset once, in the air, according to the abnormal procedures checklist.
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Re: Best not to push in the CB when there is smoke

#12 Post by Siddley Hawker » Sat Oct 28, 2017 9:14 pm

Depends what electrical buss the breaker was on. If the breaker was on a non essential buss, never reset in the air. If on an essential buss we were allowed one reset.
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Re: Best not to push in the CB when there is smoke

#13 Post by pelmet » Sun Oct 29, 2017 8:45 am

Meatservo wrote:
av8ts wrote:
Meatservo wrote:Incorrect. It depends on the breaker. Some should never be reset, some can be reset once. You follow the instructions in the QRH/abnormal or emergency checklist for your aircraft type.
Incorrect

My QRH says never in the air

Company policy is ok to reset on ground when advised by maintenance
Maybe yours does. There are lots of aircraft models in which certain breakers can be reset once, in the air, according to the abnormal procedures checklist.
Is it possible that this is a checklist from the '60's era which is out of date compared to modern practices?
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Re: Best not to push in the CB when there is smoke

#14 Post by digits_ » Sun Oct 29, 2017 9:05 am

pelmet wrote:
Meatservo wrote:
av8ts wrote:
Incorrect

My QRH says never in the air

Company policy is ok to reset on ground when advised by maintenance
Maybe yours does. There are lots of aircraft models in which certain breakers can be reset once, in the air, according to the abnormal procedures checklist.
Is it possible that this is a checklist from the '60's era which is out of date compared to modern practices?
If you are using a '60's era' checklist that is out of date compared to modern practices, doesn't that imply you are flying a complete '60's era' airplane that is out of date compared to modern practices :mrgreen: :?:
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Re: Best not to push in the CB when there is smoke

#15 Post by digits_ » Sun Oct 29, 2017 9:30 am

xsbank wrote: In this example this crew likely did not follow the smoke in the cabin procedure, they made one up.
What makes you say that? The smoke in cabin procedure is fairly vague and basically says "try to figure it out yourself"

One example is in this file on pdf nr 159 http://www.mrmoo.net/pilot/BE200/BE20%2 ... ndbook.pdf

Smoke from the middle of the cabin is usually flap motor related, but if they analyzed it as coming from the medical inverter and it solved the issue, how can you blame them?

On page 136 of the same document it say you can reset the circuit breaker if it is an essential one. You can argue if flaps are really essential, but I wouldn't nail them to the wall for judging it is essential.

The smoke and flap circuitbreaker should probably have made them connect the dots that it was the flap motor, as it is something that occasionally happens on king airs. Speculating, you could probably say that it was a fairly new/low time captain and fo (since 95% of the medevac pilots in manitoba are just meeting the province requirements), so they might have forgotten, or not been told, that the flap motor can do this. On medevac fatigue could also be a big issue for overlooking stuff like that.
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Re: Best not to push in the CB when there is smoke

#16 Post by Meatservo » Tue Oct 31, 2017 11:01 am

One factor, not necessarily in his incident but generally, is that peoples' educations focus less and less on "how things work" as time goes by. Most ground-school syllabuses, especially for planes that are 20 years old and older, assume a degree of mechanical knowledge on the part of the average wannabe-pilot. The last organized classroom-situated groundschool I attended was for a large, relatively modern transport category machine, and the electrical section was still based on the assumption that the people learning to fly this plane would already know the difference between AC and DC, how on earth a DC generator can also function as a motor and vice-versa, why the frequency from a direct-driven AC generator is considered "wild", why it needs to be rectified, what "rectified" means, what a transformer does, what an inverter does, what a "relay" and a "control voltage" does, what fuses and circuit-breakers actually do, in what sense they are "protecting" anything, why one can be reset (sometimes) and the other can't, and so on.

People get through these courses now by memorizing answers and doing multiple-choice "tests". The last groundschool I taught, not one person there knew what the difference between "AC" and "DC" is. Well, why even bother continuing from there? I mean really. What is the arm-bone-is-connected-to-the-leg-bone stuff going to mean to anyone who doesn't understand the language?

All mechanical knowledge disseminated among new pilots now is more folklore and tradition than science, because most of them don't know the science. So if the folklore says "never touch a circuit breaker" then don't ever touch one. I agree with that. But I do hear whispered tales, on dark winter nights, of Operating manuals that say some of them can be reset once.

But yeah, going back to the beginning of this thread, if there's smoke, and then I see a popped breaker, I ain't touching it. This is reinforced by the fact that I know what smoke and popped breakers have to do with one another.
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Re: Best not to push in the CB when there is smoke

#17 Post by bobcaygeon » Tue Oct 31, 2017 1:56 pm

Meatservo

I'd say a pilot with a little bit of technical knowledge is often more dangerous than one without any who just follows the checklist. they tend to remember only half the concept and forget that there are other variables involved.

The most dangerous guy I know is often the do it yourself electrician or car repair guy.
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Re: Best not to push in the CB when there is smoke

#18 Post by Meatservo » Tue Oct 31, 2017 3:05 pm

What a fantastic argument in favour of ignorance. It's not just important to understand how a machine works so you can fix it. It also helps you avoid mis-using it.

That of course is a pretty old-fashioned professional concept. I'm glad I at least started flying planes for a living when it was considered to be a worthy discipline. Now it's just an easy way to make money for slackers.

This ties in rather neatly with the automation discussion. I think the time is right to replace most of you guys with computers.
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Re: Best not to push in the CB when there is smoke

#19 Post by Cat Driver » Tue Oct 31, 2017 7:17 pm

Seems flying is becoming robotic and a thought process is discouraged.

I sure am happy I was fortunate enough to have been in aviation when thinking was looked upon as a positive trait.

It got me through fifty one years of flying for a living without damaging an aircraft.
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Re: Best not to push in the CB when there is smoke

#20 Post by complexintentions » Tue Oct 31, 2017 9:03 pm

Here's an excerpt from the Boeing B777 QRH regarding non-normal checklist usage, circa 2017:
In flight, flight crew reset of a tripped circuit breaker is not recommended. However, a tripped circuit breaker may be reset once, after a short cooling period (approximately 2 minutes), if in the judgment of the captain, the situation resulting from the circuit breaker trip has a significant adverse effect on safety.
OMIGOD it uses the word judgment, are we still even allowed to use that?

Unbelievable to hear a quasi-defence for ignorance. Well, ok, actually I guess it IS pretty believable, sadly. True, if you don't have a fecking clue about what the circuit breaker does, or controls, or what type it is, better to not touch it and let the smart people on the ground deal with it - you're just a dumb pilot, after all. Button-pusher, amirite?

Or, you could spend a bit of time and maybe learn how your aircraft works a little, what the difference is between a trip-free and non trip-free breaker, y'know, the basic electrical theory and systems stuff taught on the exams you wrote to get your license, and make an intelligent decision when required. If that's still allowed.

Don't try and be a genius, the days of sketching the whole electrical schematic are long gone as they should be. But if you're going to be a robot, don't be surprised when you're replaced by one.
The most dangerous guy I know is often the do it yourself electrician or car repair guy.
All the more reason for pilots to emulate professional tradespeople and actually know how their tools work, rather than take the weekend warrior, armchair expert approach so prevalent in the industry now.
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Re: Best not to push in the CB when there is smoke

#21 Post by pelmet » Wed Nov 01, 2017 7:38 am

complexintentions wrote:Here's an excerpt from the Boeing B777 QRH regarding non-normal checklist usage, circa 2017:
In flight, flight crew reset of a tripped circuit breaker is not recommended. However, a tripped circuit breaker may be reset once, after a short cooling period (approximately 2 minutes), if in the judgment of the captain, the situation resulting from the circuit breaker trip has a significant adverse effect on safety.
Correct....so if you have smoke in the cabin and the flap CB pops, you might say....Are they related and is it a wise idea to push this breaker back in?

If a popped CB has been discovered on your widebody jet(or another aircraft) after encountering some system malfunctions and it is looking like you might have to do a gear-up landing due to this....your judgement may make you want to discuss and consider pushing it in(assuming you are aware of the popped CB). Otherwise, you might end up doing a spectacular landing like these guys...

https://www.youtube.com/watch?v=UC8ySY_GlUk

Read more here...A gear up landing in a 767 due to a popped CB.

https://en.wikipedia.org/wiki/LOT_Polis ... _Flight_16

If you have a breaker(or breakers) popping on something unnecessary such as a toilet flush motor, best to leave them out.

https://www.tailstrike.com/020683.htm
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