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BA 777 on fire in Las Vegas

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BA 777 on fire in Las Vegas

Old 7th Oct 2015, 13:56
  #581 (permalink)  
 
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There are two parts to a safety assessment involving engines. One is the consequences to the engine itself e.g. should not catch fire, burst its cases damage its mounts or lose the ability to be shutdown (sic).

The other equally important aspect is the assessment at the aircraft level. Any AD actions need consider both and address the need to minimize either or both by corrective actions.

At this time with so little facts published it is not obvious to me what such AD update is warranted.
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Old 7th Oct 2015, 19:25
  #582 (permalink)  
 
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Actually the RP did play a significant role in the outcome of this event. The Commander asked him to go back into the cabin to check on what was happening. The RTO was at around <70kts and they had shutdown and firing of the bottles was complete. They were running the checklist and starting the APU when the RP came back up say there was a significant fire outside the aircraft and this is when the evacuation was ordered. The fire was caused by a ruptured 2" fuel line and it had spilled about 40 Gal of fuel. Both the spar valve and engine firewall shut off worked as designed. There will be more news regarding this event over the next week or so.
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Old 7th Oct 2015, 22:08
  #583 (permalink)  
 
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. Coming after the A400M accident at Seville where little of the structure remained,
Look up other such accidents where little structure remined and aircraft had traditional aluminium fuselage. It is a myth that composite aircraft enhances flammability, research has settled this question long time ago, you can google relevant scientific papers.
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Old 7th Oct 2015, 23:27
  #584 (permalink)  
 
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The Commander asked him to go back into the cabin to check on what was happening. The RTO was at around <70kts and they had shutdown and firing of the bottles was complete. They were running the checklist and starting the APU when the RP came back up say there was a significant fire outside the aircraft and this is when the evacuation was ordered. The fire was caused by a ruptured 2" fuel line and it had spilled about 40 Gal of fuel. Both the spar valve and engine firewall shut off worked as designed.
Is there any kind of time line whether the fuel valves were closed while the aircraft was moving or only after it had come to a stop?
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Old 8th Oct 2015, 03:33
  #585 (permalink)  
 
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Something that has come up in discussion with both professionals and enthusiasts over the last few weeks has been the total destruction of the composite areas of the structure.
No way to compare those, thin walled sandwich composite parts behave totally different from thick walled, monolithic composites. Compare the burn through time of a 3 layer plywood panel with that of a 10 ply panel, it will be a factor of 100 between. Every destroyed layer acts as a protection for the ones underneath, from a certain thickness it basically becomes fireproof. While melting metal runs away immediately exposing the one behind, burned layers will stay in place and protect the remaining ones. Heat transfer through aluminum and composites is totally different. Aluminum is destroyed by external fire, composies burns by itself once a fire started.
Finally both wreaks will not be a pretty sight...

The only thing we may learn from this accident is the fire scenario which should be used for tests. The scale of samples we should use for the tests, the type of flame we should use. Maybe one standard test does not give all the answers. And again (since british airtours) streched acrylic windows should get a second thought.
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Old 8th Oct 2015, 07:27
  #586 (permalink)  
 
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Fuel Valves

Originally Posted by lomapaseo
Is there any kind of time line whether the fuel valves were closed while the aircraft was moving or only after it had come to a stop?
Almost certainly, the fire handle(s) would not have been pulled until the aircraft was stopped.
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Old 8th Oct 2015, 07:35
  #587 (permalink)  
 
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RTO,

Bring the aircraft to a stop, apply the parking brake, ensure forward idle on the thrust levers and .......... wait.

Check the reason for the stop call, confirm it between ALL flight crew and then commence memory items/communication as appropriate.

For engine fire and emergency shut down the fuel cutoff switches must be selected to cutoff before the fire handle is pulled.

So, the shutoff valves and pylon isolation would have been completed once the aircraft was stopped.
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Old 8th Oct 2015, 08:32
  #588 (permalink)  
 
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For engine fire and emergency shut down the fuel cutoff switches must be selected to cutoff before the fire handle is pulled.
This procedure is relatively new as you used to be able to just pull the fire handle and the fuel valves would then be closed automatically.

Do you think the crew used this procedure correctly?
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Old 8th Oct 2015, 08:32
  #589 (permalink)  
 
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Engine Fire Handles

Originally Posted by Wilbelsturm
For engine fire and emergency shut down the fuel cutoff switches must be selected to cutoff before the fire handle is pulled.
While the above statement is procedurally correct and proper, the fire handles can still be pulled with the engine fuel control switches in RUN, by pushing the fire handle override buttons in order to release the mechanical locks. (this would be unnecessary if there was an active fire warning for the associated engine)

This is because there needs to be a separate and independent means to shutdown an engine.

Last edited by wanabee777; 8th Oct 2015 at 08:52.
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Old 8th Oct 2015, 08:37
  #590 (permalink)  
 
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.composies burns by itself once a fire started.
Not true. The 'charring' effect stops fire propagation, look up FAA docs from 787 certification.
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Old 8th Oct 2015, 09:13
  #591 (permalink)  
 
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by pushing the fire handle override buttons in order to release the mechanical locks.
This is also unnecessary as moving the CUTOFF switches to cutoff also unlocks the engine fire switches hence removing the need to press the override. (which are pretty awkward to use to say the least in my opinion!). The system is there to prevent inadvertent pulling of the handle on a live engine. The associated mechanical release is also unlocked in the event of a fire indication.

The FCOM lists the actions of closing the CUTOFF switches as

Closes the fuel valves
removes ignitor power
unlocks the engine fire switch

I believe the warning in the QRH is there to prevent crew 'regularly' using the override switches to cut the engine and to follow the correct procedure.
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Old 8th Oct 2015, 09:24
  #592 (permalink)  
 
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Originally Posted by Wirbelsturm
This is also unnecessary as moving the CUTOFF switches to cutoff also unlocks the engine fire switches hence removing the need to press the override. (which are pretty awkward to use to say the least in my opinion!). The system is there to prevent inadvertent pulling of the handle on a live engine.

The FCOM lists the actions of closing the CUTOFF switches as

Closes the fuel valves
removes ignitor power
unlocks the engine fire switch

I believe the warning in the QRH is there to prevent crew 'regularly' using the override switches to cut the engine and to follow the correct procedure.
All true. However, a catastrophic failure could render the fuel control switch(es) useless. Therefore the need for redundancy.
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Old 8th Oct 2015, 09:32
  #593 (permalink)  
 
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Not true. The 'charring' effect stops fire propagation, look up FAA docs from 787 certification.
I may tell you an old trick from a composites repairman...
If you have to repair a glassfibre aircraft and do not know the exact layup, just cut out a piece, light it, lett it burn off, sort out the charred layers of fabric and identify their grade and orientation.
Believe me, they do burn once you light them. Completely. Al least if they are a piece, and not a large sample which you exposed to fire in a local area in the center only, in that case you are right. And that is what the FAA tests.
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Old 8th Oct 2015, 09:40
  #594 (permalink)  
 
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All true. However, a catastrophic failure could render the fuel control switch(es) useless. Therefore the need for redundancy.
You are correct but it is important to differentiate what these controls do.

The cutoff switches close ONLY the fuel valves whereas the fire handles cut off the spar valves and fuel valves, trip the engine generators, closes the bleed valves, isolate the hydraulics, depressurizes the associated engine driven pump and removes power to the thrust reverser isolation valve.

So whilst a catastrophic failure might well remove the use of the cutout switches I think you would be pulling the fire switch anyway and the discussion was the correct procedure in the event of an evacuation RTO.

Boeing do not want pilots routinely over riding the fire switches as an inadvertent pull of the switch requires a massive engineering input. Hence the QRH warning is in bold and lined above and below in red.

WARNING:
Do not pull the ENGINE FIRE switches before the FUEL CONTROL switches are in the CUTOFF position.


I suppose Boeing could have put in a caveat somewhere of 'try not to land without the gear being down', it can be done but only in times of great necessity!!!!
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Old 8th Oct 2015, 10:03
  #595 (permalink)  
 
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I guess this debate centers on how you define and apply the word "must".

My company's FAA approved QRH for the 777 does not include the WARNING that your QRH has.

Last edited by wanabee777; 8th Oct 2015 at 10:21.
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Old 8th Oct 2015, 10:32
  #596 (permalink)  
 
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I guess this debate centers on how you define and apply the word "must".

My company's FAA approved QRH for the 777 does not include the WARNING that your QRH has.
Absolutely! We are using the Boeing Version direct which has it printed as above. Currently at Rev. 52

Horses for courses I suppose.

At the end of the day as long as the donks are switched off before we disgorge passengers onto the tarmac then the job is done.
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Old 8th Oct 2015, 10:40
  #597 (permalink)  
 
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That explains it!

We are currently only at Rev 15.
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Old 8th Oct 2015, 14:05
  #598 (permalink)  
 
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One would have imagined that with that low airspeed during a RTO the airplane was stopped before any fire switches were pulled per Boeing SOP.
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Old 8th Oct 2015, 14:07
  #599 (permalink)  
 
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Where do you come up with this stuff. The has been Boeing SOP since the 707
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Old 8th Oct 2015, 14:17
  #600 (permalink)  
 
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Boeing SOP's

Probably even before the B-17.
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