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-   -   Boeing CB statement contradictiom (https://www.pprune.org/tech-log/567604-boeing-cb-statement-contradictiom.html)

Intruder 15th Sep 2015 00:18

From the 744 QRH Instructions:

Flight crew reset of a tripped fuel pump circuit breaker or refuel circuit breakers is prohibited. In flight, reset of any other tripped circuit breaker is not recommended. However, these other tripped breakers 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. On the ground, flight crew reset of any other tripped circuit breaker should only be done after maintenance has determined that it is safe to reset the circuit breaker.

Capt Chambo 15th Sep 2015 02:38


.. keeping in mind, of course, that the label on the CB may not indicate ALL the services which take power from that circuit ie you don't necessarily KNOW what may have a problem ... you just might give yourself an unwanted surprise by playing with the panel.
Wise words form J-T

G00gle National Airlines DC10 Flight 27,back in 1973, and look particularly for the CVR transcript. There you should find a discussion between the Capt. and the Flight Engineer and the pulling of an N1 Tachometer CB, and the consequences.

john_tullamarine 15th Sep 2015 12:25

Some examples of note in the last few posts .. the prosecution rests.

Park it somewhere non-limiting and have a coffee.

I'm with you, good sir .. heroics are fine if all motors run down and one's options become severely limited. For other cases, the sit on hands strategy appears to be a sound IA.

I've just finished a long term contract managing a highly modded fleet of whiz bang electronic birds .. even the elec DERs had a deuce of a time figuring what did what .. a couple of problems took many weeks - with OEM input - to resolve ... and folks want the skipper to figure it out in a flash ? Madness unless you are on an ancient bird of low complexity.

EEngr 15th Sep 2015 15:57


.. keeping in mind, of course, that the label on the CB may not indicate ALL the services which take power from that circuit ie you don't necessarily KNOW what may have a problem ... you just might give yourself an unwanted surprise by playing with the panel.
Good advice. But its also a sign of poor engineering. What's the difference between you pulling a CB and it's downstream system having a fault and tripping it (as intended). Other then the loss of function of the system fed by that breaker, there had better not be any 'surprises' involved with it's operation. Other systems dependent on the faulted one should, to the greatest extent possible, degrade gracefully.

Depending on how one reads the FARs, this could be interpreted as a certification issue.:8

Metro man 16th Sep 2015 01:16

Pulling CBs to reset systems is standard for Airbus pilots. There is a whole section of computer resets in the QRH. Some are on ground only and some can be done in flight. Engineers resets get even more involved.

Pulling multle CBs and starting the stopwatch, all in a days work.

john_tullamarine 16th Sep 2015 11:22

a sign of poor engineering

Reality, I'm afraid. The problem lies not with what is published in operational documents but with innovative bush lawyer (engineer ?) pilots with less than the full story.

There is a whole section of computer resets in the QRH

No problems with that .. the research has been done and, barring mistakes (which can and do occur in a design office the same as anywhere else), the crew can have confidence that the procedure will do what is advertised.

A whole universe away from a pilot's making it up on the fly ...

t6 sparky 16th Sep 2015 17:23

Also the fwd e/e bay:)

Juri75 16th Sep 2015 19:52

When you have the time, contact your MCC via radio or ACARS to discuss the reset of a CB. Most of the time they pop for a reason. When you don't have such time, keep flying the plane.


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