A cockpit question

[WebMaximus 372]

Hi,What are all those button panels that are situated on the wall behind the PIC's and FO's seats in the cockpit? Guess they aren't that important since they are very seldom mentioned or have a missed something here maybe ;-)?

[Mats_J 2]

RichardThat would be the circuit breaker boards. ;-)For an indepth explanation of all the C/Bs in the NG I'm reffering to the below document:http://www.fmcguide.com/media/cb678.pdfHave fun! :-)

[Guest wee_davie_2612]

Hey,Those are the circuit breaker panels. Only important in real life :)CheersDavid

[WebMaximus 372]

Looked at the link you suggested and that would work just great as a sleeping pill for me ;-) But still don't get what they are used for and when - to turn on/off all different systems or what?

[Guest Matthew Murray]

Each system or systems are connected into this board. Think of the CB Board like a large electrical socket, that each system is plugged into. Each system has a CB to prevent overloading of the system. Now, if we pull a 'CB', we disconnect the power source to that system, or when the CB decides to "break", power is cut and the system protected. Reseting the CB's inflight is a big no-no. The engineer/mechanic will find the cause as to why the CB tripped, before reseting th CB!In short, forget about them...it's really just for mechanics..and something to read on those long sectors hahaha

[P CLASS=style1] Matthew Murray [/P][P][sPAN CLASS=style1]-|www.precisionmanuals.com|-[bR][/sPAN]

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[marcom 139]

Normally they are not used.They are just like the circuit breakers in your home.There are three basic scenarios where the flight crew would touch them:- let's say something is not working right. There is smoke coming from one of the displays or from an isolated location. You can pull the respective circuit breaker to remove all power to the associated system. In modern aircraft, this is the only way to actually switch off an electronic equipment. Electric systems are coupled to different electric busses - thus the only alternative way to switch a system off would be to cut power to the bus - which would also kill many other (working) systems.-another scenario: there was a slight rise in voltage/frequency due to power source change or simply turbulence or whatever. This caused a system to temporarily fail (a transient fault). To save the electric bus, the system "popped" its circuit breaker. In this scenario, the crew can try to reset the circuit breaker once. If the system is actually inoperative, the circuit breaker will pop back out. If its working, it will stay in and you'll have reseted the system.-an electric component (such as the FMC) is doing erratic things. Or something is not working as it is supposed to. You can then try to pull the circuit breaker and push it back in. This causes the respective system to "reboot" or reset itself. Sometimes this actually helps! (ask any airbus flyer) :-)Maintenance will also use the circuit breaker to turn off specific systems if work is being carried out. Or to shut something down that is causing annoying noise (for example the vibrator behind the stby altimeter).That's about it :-)Regards,Mark

[marcom 139]

Matthew,some CB's can be actually reset in flight. What airline are you referring to that doesn't allow reseting of CB's?Mark

[WebMaximus 372]

Thanks alot, you guys are the best! It's really facinating how much you can learn just by spending some time in this forum!!All the best,

[bobbyjoh 11]

Just a quick story about own real flying experience and cb's. I was flying a KC135 out of Kadena AB in Okinawa when we had fuel injestion into the cockpit, long story on how that happen. What we had to do was disable everything on the airplane quickly. Pulling the CB shut down all electrical systems that could have arc and blown us to kingdom come.There were also times when an electrical device did not respond to panel switches. We would use the CB to cycle them. The best explanation is just like someone said, they work just the ones in your house. If some device on the plane overloads then it pops the CB preventing fire or damage to the box.CheersBob

[Qavion 19]

"Only important in real life"And only important if they're out (tripped) when they shouldn't be out ;-)Circuit breakers can be reset in flight in our airline... at the Captain's discretion... as long as they are not related to the fuel system.Cheers.Ian.

[Guest LimeEco]

<>If you have time..Can you explain how that happened?.Sounds pretty interesting...as well as dangerous!Best regards,Joaquin,LEMD

[AvA757Pilot 6]

In 1982 an MD-80 crashed on departure from Detroit becuase the flaps had not been configured for takeoff. The Cockpit Voice Recorder showed that the warning alert never sounded when the throttles were advanced for takeoff. It was theorized that the crew had pulled the circuit breaker, although no one could surmise why they would have done that.In another instance a few years earlier, a 727 was at cruise and the crew were discussing the possibility of increasing cruise speed by deploying the leading edge slats. They disabled the circuit breaker controlling the inhibit function and deployed the slats. The airplane responded by entering a severe dive from which they were only able to recover after plummeting thousands of feet by lowering the landing gear.These are 2 examples of why some airlines do not allow the flight crew to "play with the circuit breakers".Roger Curtiss