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BA - Fire Suppression System Malfunction

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BA - Fire Suppression System Malfunction

Old 6th May 2020, 17:44
  #41 (permalink)  
 
Join Date: Jun 2001
Location: Rockytop, Tennessee, USA
Posts: 5,748
Originally Posted by Local Variation View Post
Airbubba,

The manual override will be to release the extinguishment. Due to the potential for the 2nd detector to not activate (for whatever reason, aka citing), you need the ability to enable if you can clearly see a fire event. The eyes and nose remain the best forms of detection regardless of technology development.
Thanks for that explanation.

So is there no manual cancel during the seconds before the foam flows? Or was inadvertent activation not considered in the design? Or in the regulations?

It seems that there are very few saves and many costly false activations with this system.

As one insurer observes:

These systems can automatically and effectively extinguish a fire by smothering it. However, they are not without risks — risks that can be especially concerning given that hangar foam fire suppression systems are known to discharge inadvertently in many instances. Consequently, the pros and cons of foam fire suppression systems are frequently debated by stakeholders including aircraft owners, hangar operators/owners, fire safety experts, trade associations, FBOs and others.

Unintended Consequences of Inadvertent Hangar Foam Discharges

When a hangar foam fire suppression system inadvertently discharges the results can be damaging or even deadly. For example, in 2014 a civilian worker at Eglin Air Force Base died after being trapped in a foam-filled hangar during an inadvertent system discharge.

Other unintended consequences produced by foam fire suppression system discharge include:
  • Damage to aircraft. While the foam can prevent the aircraft from being destroyed by fire, it can damage sensitive systems in the process, requiring expensive repairs or replacement of components.
  • Damage to other equipment. Other assets in the hangar including vehicles, tools and support equipment can be damaged by fire suppression foam.
  • Loss of business. From missed flights and costs associated with arranging for substitute aircraft in place of damaged aircraft, to harm to an operator’s reputation, an accidental foam discharge can negatively impact operations in many ways.
  • Environmental risks. If foam escapes containment within the hangar, environmental contamination can occur and the consequences can be far-reaching.
These are just some of the issues resulting from false activations of foam fire suppression systems.

National Fire Protection Association (NFPA) 409 – Standard on Aircraft Hangars

NFPA 409 was defined to be the “standard that helps safeguard life and property through the requirements for the proper construction and fire protection of aircraft hangars used for aircraft storage, maintenance, or related activities.” While no one in aviation would dispute that NFPA 409 is well-intentioned and that adhering to it is critical in many circumstances, some people do question whether perhaps it goes too far and is too burdensome in certain applications.
https://www.global-aero.com/pros-and...ssion-systems/
Airbubba is online now  
Old 6th May 2020, 20:52
  #42 (permalink)  
 
Join Date: Apr 2006
Location: Lestah
Posts: 162
Originally Posted by Airbubba View Post
Thanks for that explanation.

So is there no manual cancel during the seconds before the foam flows? Or was inadvertent activation not considered in the design? Or in the regulations?

It seems that there are very few saves and many costly false activations with this system.

As one insurer observes:



https://www.global-aero.com/pros-and...ssion-systems/
The double knock is there to provide some level of protection against unwanted activation. Double knock being two detection devices needing to trigger. Alternatively, co-incidence detection utilising two specific detection trigger points adds another layer of protection.

Pre-fire, visible count down timers, flashing strobes, sounders, controlled delay blocks, hold off relay timers are permitted, but my limited detailed standards knowledge of fixed extinguishing (FE) systems does not extend to advising on say, a stop or abort button. Certain FE types permit a timed block window for flow.

I would stick my neck out and hazard a guess that abort is a probable optional system add-on based on specification. But that introduces a whole realm of monitoring and control etc (if the applied standard permits). A verified activation being aborted is something the Insurers would pick up on straight away.

As an aside, fire alarm delay blocks in general are limited to a number of minutes, typically up to just under double digit max in the UK for search and validation time. Big sites allow a variation to be applied as it can take more than 10 mins to physically reach the furthest point in the building search area. Airports are very much in scope here.
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Old 6th May 2020, 21:40
  #43 (permalink)  
 
Join Date: Feb 2020
Location: London
Posts: 1
Originally Posted by Airbubba View Post
Thanks for that explanation.

So is there no manual cancel during the seconds before the foam flows? Or was inadvertent activation not considered in the design? Or in the regulations?

It seems that there are very few saves and many costly false activations with this system.

As someone who speaks from bitter personal experience - no, there is no way you can switch the system off once it is started...
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