Fire extinguishers after abort
Thread Starter
Joined: Dec 2002
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From: flightdeck/earlyhours commute
Fire extinguishers after abort
B737 and B757
After abort, during Engine fire recall items, firing both bottles.
I was always of the understanding, and recently confirmed by someone I respect very highly, that there should be a delay between firing the bottles, to allow them each to fully discharge. Otherwise, one may not be fully discharged, ad so you lose the benefit of part of the contents. As they utilise the same plumbing, to route to the same outlets, there needs to be a delay.
At another organisation, I have been told that both are to be fired into a burning engine, without a delay between them.
ie. Rotate the fire handle, orange discharge light, rotate the handle, orange discharge light. With no delay between seeing the first discharge light, and rotating for the second bottle.
In the air, it's 30seconds between discharges, to allow the full discharge and note any change or lack.
Is the discharge light related to drop in pressure, or simply that the squib has fired?
I feel the subtle difference during the ground related drill is being lost.
Comments?
Tech response?
After abort, during Engine fire recall items, firing both bottles.
I was always of the understanding, and recently confirmed by someone I respect very highly, that there should be a delay between firing the bottles, to allow them each to fully discharge. Otherwise, one may not be fully discharged, ad so you lose the benefit of part of the contents. As they utilise the same plumbing, to route to the same outlets, there needs to be a delay.
At another organisation, I have been told that both are to be fired into a burning engine, without a delay between them.
ie. Rotate the fire handle, orange discharge light, rotate the handle, orange discharge light. With no delay between seeing the first discharge light, and rotating for the second bottle.
In the air, it's 30seconds between discharges, to allow the full discharge and note any change or lack.
Is the discharge light related to drop in pressure, or simply that the squib has fired?
I feel the subtle difference during the ground related drill is being lost.
Comments?
Tech response?
Joined: Jan 2006
Posts: 2,480
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From: In a far better place
The BOTTLE DISCHARGED light illuminates when the respective bottle pressure decreases below circa 250 PSI.
Chances are the fire brigade is on the scene able to fight any fire that may be present. Important to know, 30 seconds can mean the difference of survival or death if a fire actually exists.
Chances are the fire brigade is on the scene able to fight any fire that may be present. Important to know, 30 seconds can mean the difference of survival or death if a fire actually exists.
Last edited by captjns; 21st November 2011 at 14:53.
Joined: Jun 2001
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From: UK
Have seen it done both ways by different operators!
capjns, agree with your sentiments but there a few airports where I wouldn't be too surprised if it took a few minutes before the fire trucks were on the scene in the event of fire after a rejected take off!
For a liability point of view, follow your company procedures. If they advocate disregarding the 30 second delay then that goes against Boeing - just make sure it's in writing from the Company and keep a copy for reference.
capjns, agree with your sentiments but there a few airports where I wouldn't be too surprised if it took a few minutes before the fire trucks were on the scene in the event of fire after a rejected take off!
For a liability point of view, follow your company procedures. If they advocate disregarding the 30 second delay then that goes against Boeing - just make sure it's in writing from the Company and keep a copy for reference.
Joined: Mar 2002
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From: Florida
Has the fuel dissipated
has the ignition source stopped (cooled etc.) ?
If so go ahead and fire your last remaining bottle according to SOP
If not why not wait between discharges to give it a chance ?
has the ignition source stopped (cooled etc.) ?
If so go ahead and fire your last remaining bottle according to SOP
If not why not wait between discharges to give it a chance ?
Joined: Mar 2002
Aviation Qualifications: ATPL
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From: Seat 1A
Originally Posted by Fireflybob
If they advocate disregarding the 30 second delay then that goes against Boeing
Joined: Jun 2001
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From: Blighty
As for Boeings, I've only flown the 747 and the installation we had was one bottle per engine with the option of being able to discharge the adjescant engine's bottle if the first didn't do the job. The advice was not to fire both at once becuse the two systems were unified though a shuttle valve which would allow the bottle with the higher pressure to discharge. The danger of this system is that if the bottles become evenly matched in pressure, the shuttle valve could stick in the middle and the burning engine would get the contents of neither.
Joined: Sep 2010
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From: earth
Is your engine burning or is it a bleed leak? Chop fuel, pull the handle and take a breath. If it is a fire and you can not extinguish with one your chances on the 2nd are less, I view the 2nd bottle as more of a redundant system than an effective one.
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From: Home soon
Chances are the fire brigade is on the scene able to fight any fire that may be present. Important to know, 30 seconds can mean the difference of survival or death if a fire actually exists.
True.
30secs is quite long when an evacuation should be done in 90secs or less.
True.
30secs is quite long when an evacuation should be done in 90secs or less.
Joined: Jun 2000
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From: last time I looked I was still here.
"30secs is quite long when an evacuation should be done in 90secs or less."
And that is from the order to evacuate. Now that Boeing have advised it should be a 'read & do' checklist it takes quite a few seconds to reach the evacuation order. Any opinions why it is no longer a memory drill?
And that is from the order to evacuate. Now that Boeing have advised it should be a 'read & do' checklist it takes quite a few seconds to reach the evacuation order. Any opinions why it is no longer a memory drill?
Joined: Jan 2006
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From: In a far better place
To ensure all required steps are carried out in accordance with the operator's approved non-normal procedures. Read and do also ensures proper handling of the fire bottles based on the current situation.
