Aircraft and the fire danger

Valujet flight 592 took off from Miami Florida bound for Atlanta Georgia on 11 May 1996, killing all 110 people on board. A few minutes after departure, the crew heard a bang, and they began to lose electrical power. A few seconds later, a flight attendant opened the cockpit door and reported a fire in the passenger cabin. Investigators heard people yelling "Fire" from the cabin on the CVR when the door opened. It was determined that improperly packed oxygen generators activated in the cargo hold, starting a fire.

SwissAir flight 111 slammed into the ocean off Halifax, Nova Scotia on 2 September 1998, killing all 229 people on board. Investigators determined that a fire had started in the Inflight Entertainment system (IFE). The crew had no fire detection system in that area of the aircraft, so their first clue that something was wrong was smoke in the cabin. By then it was already too late. They followed the checklist and proceeded out over the ocean to dump fuel, and on the way back to Halifax to land as a precaution, they lost all power, and the aircraft crashed.

UPS flight 6 departed Dubai for Cologne Bonn Airport on September 3 2010. Approximately 120 miles after departure the crew reported a fire in the cockpit, and requested a return to Dubai. They were offered a diversion to Qatar, but chose to return to Dubai. They were too high for the runway they were cleared to, so they began a right turn to circle and descend. During the turn, the aircraft crashed in an unpopulated area, killing both crew members. Investigators determined that some of the thousands of lithium ion batteries on board caught fire in the cargo compartment, leading to the crash of the aircraft.

There are others that can also be cited, such as the Saudi Arabian Airlines flight 163 fire that killed all 301 people on board. Or the two cargo aircraft that have been destroyed in the last three years due to fire.

After the Valujet crash it was mandated that all aircraft have fire detectors in the cargo hold, to alert the crew of fire. But it's now 25 years since SwissAir 111, and the fire in the walls, and currently the only requirements for fire detection on an aircraft are the cargo holds, the engines, and the lavatories. If a fire similar to SwissAir 111 were to break out on a plane today, it could very easily lead to the same results, and a large loss of life.

The newer aircraft, like the 767-400, the 787, the A380 and others have more IFE systems, more wiring, and more batteries, including lithium Ion batteries. All of which increases the odds of fire on board. It's estimated now that one in every 15,000 flights has a smoke event on board. Almost all of them are just smoke, but how long will it be until one of them isn't just smoke? How many more people will have to die before more fire sensors are installed on aircraft, in places that make sense, such as around the IFE systems?

flightglobal.rbiblogs.co.uk...

reply to post by Zaphod58


You make me not want to go on vacation anytime soon

How are the 737-800's?

reply to post by Zaphod58


Zaphod, I want to thank you for this and ask a question you have opened the door for. It's something I've wondered from time to time and is directly on point to your OP here.

Why is it the case that they don't have fire detection equipment of even a basic level, where obvious gaps in factory systems exist? Is the system for aircraft so tight and absolute that nothing will be permitted that isn't run through a long, complex and exhaustive testing system? Even a $15 smoke detector that could at least be stuck to make enough racket to be heard?

The real question here though is why these fires burn at all, when not in the Passenger Compartment? The Cargo holds can be pressurized or not..is that right? If not, can they be 100% and entirely cut off from air circulation into the cabin? If SO...the tail recirculation system for cabin air could be engaged (as they had to do back when smoking was allowed in-flight) to insure plenty of fresh air to the people...while the fire is handled below?

---- Going by the above, and hoping you know enough off the cuff to pretty much answer all that in your head for this question..

Why don't they have Halon or similar systems covering all non-human occupied areas of an aircraft, which can or by design are shut off from the air space of people onboard? Fire can't live if it can't breathe...so wouldn't Halon end the problem before it began? Maybe even C02, since it tends to settle and wouldn't want to rise into the compartment above..while still displacing oxygen to starve it? (C02 wouldn't destroy the cargo hold and everything in it, either..lol)

Thanks for your indulgence on my curiosity. You're great on that.

reply to post by Zaphod58


Well flying has always been risky...still fires are rare. One never knows when it's their last day.

Thats kinda scarey

IS there anything the aviation industry could be doing more to prevent these fires?

reply to post by Zaphod58


I'm not sure whether or not there will be any more episodes, or if it has ended(or been cancelled), but during June/July, there were 4 episodes of the show Terror in the Skies.

Terror in the Skies sees aeronautical engineer Brendan Walker taking a look at different shocking footage of aviation incidents and near misses, and tells stories of survival and bravery in the sky.

An interesting series. I'm sure it can still be found online.

He talked about a couple occasions when the Lithium batteries had started fires on-board. I can't remember the exact details, but I'm pretty sure one of them was about a fire that started on one of the insanely expensive Airbus'. (it may have still been on the runway, but a fire nonetheless.)

I just found this↓article(which is from Feb. 2013). So apparently, they did learn from that mistake.

Airbus is activating what it is calling “Plan B” and dropping lithium-ion batteries from its newest composite airliner even as Boeing continues investigating why the technology has created epic problems for its flagship 787 Dreamliner.

www.wired.com...

Wrabbit2000

Why is it the case that they don't have fire detection equipment of even a basic level, where obvious gaps in factory systems exist? Is the system for aircraft so tight and absolute that nothing will be permitted that isn't run through a long, complex and exhaustive testing system? Even a $15 smoke detector that could at least be stuck to make enough racket to be heard?

That's a lot of questions, but I'll do my best to answer them.

Airlines, and designers are at the point now where every bit of weight, and every bit of space has to be accounted for. Anything that adds weight is frowned upon, and with a fire detection system, you could be adding as much as a couple of hundred pounds between wiring, detectors, and cockpit alerts. That means slightly less cargo, etc. So they're fighting to keep from having to lose that.

Everything that does go on an aircraft goes through an extensive testing period, especially new technologies. They have to be able to show that it can go a certain amount of time between failures to get it certified.

The real question here though is why these fires burn at all, when not in the Passenger Compartment? The Cargo holds can be pressurized or not..is that right? If not, can they be 100% and entirely cut off from air circulation into the cabin? If SO...the tail recirculation system for cabin air could be engaged (as they had to do back when smoking was allowed in-flight) to insure plenty of fresh air to the people...while the fire is handled below?

Here's one scary reason. The MD-11 (SwissAir 111, and thankfully almost none are left flying passengers) uses wiring that the military banned in all aircraft, and retired any that used it. Once it starts to burn, it burns fast, hot, and is almost impossible to put out.

As for the cargo holds, they are pressurized but not heated. If the hold were depressurized and the cabin pressurized, you could have a floor collapse under the right conditions, and your control cables run under the floor. You can stop the flow of air into the cargo hold, which keeps more air from getting into the fire, but you can't depressurize it.

Why don't they have Halon or similar systems covering all non-human occupied areas of an aircraft, which can or by design are shut off from the air space of people onboard? Fire can't live if it can't breathe...so wouldn't Halon end the problem before it began? Maybe even C02, since it tends to settle and wouldn't want to rise into the compartment above..while still displacing oxygen to starve it? (C02 wouldn't destroy the cargo hold and everything in it, either..lol)

Thanks for your indulgence on my curiosity. You're great on that.

They've begun to put firefighting systems in the cargo holds. They use either HALON or Co2 extinguishers, and have to be able to discharge for an hour (long enough for the aircraft to get on the ground). They also have begun to use materials that don't burn, and actually resist burning (no burn through with temps up to 1700 degrees for some lined areas, and 400 degrees for the overhead lining in the cargo hold), as well as self extinguishing materials.

All that is great for the cargo hold, which probably would have saved Valujet and UPS. But that doesn't even begin to touch on the SwissAir flight. The fire there began in the IFE in the first class cabin, behind the wall. Even though the IFE was off, it caused a short circuit in the wiring, which began to burn. The linings, and the wire insulation went up, and by the time the smoke was noticed in the cockpit, behind the wall of the fuselage was almost entirely engulfed in flames. It burned into the upper portion of the cockpit, where it eventually burned through into the back of the cockpit.

That is what needs to be addressed.

Boeing has a great article on fire suppression systems in the cargo hold, and how to stop cargo fires:

www.boeing.com...

reply to post by BrokenCircles


Boeing ran into a lot of problems with them, and Airbus learned from that. When the Dreamliner was grounded, Airbus announced an immediate change to the batteries on the A350, accepting the higher weight of more batteries for the fewer problems route.

What's insane is that it's illegal to transport Li batteries on passenger aircraft, because of the hazard. But it's apparently ok to have them on the plane to power it.

reply to post by MystikMushroom


The only real problem the 737s have had was with the rudder PCU. Under certain circumstances the PCU used in the 200 and 300 series would reverse after flying at altitude for awhile. It would freeze, and when the hot hydraulic fluid hit it, it would cause it to reverse, which led to the crash of two aircraft with the loss of everyone on board, and a few other close calls. That problem has since been rectified, and it hasn't happened again in a really long time.

OtherSideOfTheCoin
IS there anything the aviation industry could be doing more to prevent these fires?

Self extinguishing materials in the cabin liners, more detectors around the cabin, crew fire extinguishers could all be fitted onto the aircraft for a fairly minor cost and weight impact. And most importantly, changing the wiring used. There is a wiring that could be used that is highly resistant to fire, and almost impossible to ignite. When it does ignite it tends to go out fairly quickly and quite easily.

I thought they didn't manufacture HALON anymore?

I worked for a fire & gas detection team one summer in an oil field and was told that our oil field and the military had the two largest stockpiles of HALON left in the world. Don't know how true that is, but I remember those big old red tanks!

They could put CO2 systems in the cargo hold, could they not? It might suffocate people's pets, but it'd coke out any fire down below. What about making the walls air tight and flooding them with CO2?

I remember working with the CO2 systems, and they were considered much more dangerous than the HALON ones.

reply to post by MystikMushroom


They have the choice between a HALON system or a Co2 system in the cargo hold. Either one will work, and is required to fire for an hour. You have to have one of the two on board for the aircraft to be certified.

Here's a Boeing document about cargo hold fire detection and suppression standards.

Back when I was a mechanic (70's - early 90's) re-taping the joints in cargo holds was a regular and tedious job using "airtight" fiberglass tape to preserve the oxygen deprivation characteristics required by class D holds.