JulianUK From United Kingdom, joined Apr 2006, 105 posts, RR: 0 Posted (6 years 3 weeks 1 day 19 hours ago) and read 3340 times:
There was a recent landing by a 747 of BA following cargo/baggage hold alarms showing a fire there. What is the policy of an alarm going off, is it straight down for a landing or are there various things to do first. I imagine that there are fire extinguishers in the baggage area, but can you decompress that area on its own to starve it off oxygen in attempt to slow the rate of fire?
MarkHKG From United States of America, joined Dec 2005, 956 posts, RR: 2 Reply 1, posted (6 years 3 weeks 1 day 18 hours ago) and read 3327 times:
I don't think you can depressurize the cargo hold on its own...there are vent holes in the cargo hold and passenger cabin that equalize pressure between both the compartments in the event of a sudden decompression to prevent the cabin floor from collapsing onto the hold.
Release your seat-belts and get out! Leave everything!
Aogdesk From United States of America, joined Jun 2004, 930 posts, RR: 4 Reply 2, posted (6 years 3 weeks 1 day 18 hours ago) and read 3327 times:
I'm not a pilot (I did however stay at a Holiday Inn Express last night), BUT from a MX perspective, the first two things you would do is silence any aural warnings (so you can think), and then do a fire system test. Beyond that, perhaps a pilot can elaborate.
CosmicCruiser From United States of America, joined Feb 2005, 2045 posts, RR: 18 Reply 3, posted (6 years 3 weeks 1 day 17 hours ago) and read 3329 times:
1. phase ones (memory items) MD-11...fire the bottle
2. call for the Cargo Fire Lower A or B checklist
3. Land at nearest suitable airport.
TristarSteve From Sweden, joined Nov 2005, 3489 posts, RR: 35 Reply 4, posted (6 years 3 weeks 1 day 17 hours ago) and read 3324 times:
Large aircraft have fire alarms and extinguishing systems.
Small aircraft may have neither!
Anyway on a B744 you have a set of four fire bottles.
When the alarm goes off you arm the fwd or rear hold extinguishing system.
The same bottles are used for both holds, but once you have started to send the halon to one hold, you have no protection in the other.
Arming the system turns off all air that enters or leaves the hold to isolate it.
Also some fans stop. The lav and galley fans, the recirc fans the galley chiller fans, and pack3 closes down.
Various valves close in the equipement cooling and cargo heating systems.
Then you press the relevant fire extinguisher button.
The hold is immediately filled with Halon. Two bottles of halon are discharged into the hold. and 30 mins later two more bottles are fired. These discharge halon slowly to keep the hold topped up for up to about 3 hours.
Then you land at the nearest suitable airport as quickly as possible.
It is more complicated than that, depending on when you land etc. but be aware halon will continue to flow into the hold after landing. You cannot stop it.
Tod From Denmark, joined Aug 2004, 1597 posts, RR: 3 Reply 5, posted (6 years 3 weeks 1 day 17 hours ago) and read 3318 times:
Quoting MarkHKG (Reply 1): I don't think you can depressurize the cargo hold on its own...there are vent holes in the cargo hold and passenger cabin that equalize pressure between both the compartments in the event of a sudden decompression to prevent the cabin floor from collapsing onto the hold.
In addition to addressing rapid decompression, the openings between the main deck and below provide the standard airflow path during normal operations.
Quoting TristarSteve (Reply 4): Arming the system turns off all air that enters or leaves the hold to isolate it.
To stop the air from leaving, wouldn't that require shutting the outflow valves?
Since, except for the lav/galley vent system, all the pax cabin air flows via the side of body shear panels or trusses to below the floor on its way to the outflow valves, how do you stop this unless all air packs are shut down?
TristarSteve From Sweden, joined Nov 2005, 3489 posts, RR: 35 Reply 7, posted (6 years 3 weeks 1 day 16 hours ago) and read 3299 times:
Quoting Tod (Reply 5): To stop the air from leaving, wouldn't that require shutting the outflow valves
The air that exits the pax cabin does not flow through the freight hold. The freight hold is maintained as a sealed compartment except for the heating ducts that go in and out of it.
All the fans are shut down to prevent any smoke that escapes from the freight hold from entering the pax cabin as these fand get their supply from the gap around the freight hold.
Quoting MarkHKG (Reply 1): I don't think you can depressurize the cargo hold on its own...there are vent holes in the cargo hold and passenger cabin that equalize pressure between both the compartments in the event of a sudden decompression to prevent the cabin floor from collapsing onto the hold.
These vents do not go into the freight hold, but into the gap between the freight hold and the aircraft skin. There are separate blow out panels in the freight hold which would open if there was a pressure difference across them. They are there to cover a freight door opening in flight and were introduced after the TK DC10 at Paris in early 70s.
I remember when we modified the Tristar in 1977.
On the B737-2/3/4/500 and many other similar era aircraft the sealed freight hold is all there is to put the fire out. The design case relies on the fire running out of oxygen in the hold!!!
MarkHKG From United States of America, joined Dec 2005, 956 posts, RR: 2 Reply 9, posted (6 years 3 weeks 1 day 14 hours ago) and read 3274 times:
Quoting TristarSteve (Reply 7): On the B737-2/3/4/500 and many other similar era aircraft the sealed freight hold is all there is to put the fire out. The design case relies on the fire running out of oxygen in the hold!!!
Which would do little if, for some reason, the fire was caused by improperly packaged chemical oxygen generators that activated accidentally in the hold...*cough cough* Valujet *cough*
Release your seat-belts and get out! Leave everything!
AGM100 From United States of America, joined Dec 2003, 5407 posts, RR: 21 Reply 10, posted (6 years 3 weeks 1 day 5 hours ago) and read 3198 times:
As far as I know every passenger aircraft operating P 121 must have extinguishing systems in the cargo bays. I do not think that EASA has initiated the mandate yet but it probably is coming. The 737/MD80 systems we have provided have remote smoke detectors that alert the crew though a alarm/CP mounted on the P5. The system includes Halon bottles mounted and plumbed (usualy fwd of the aft CB). The halon ejection system is timed to allow fire containment over a period of time, I think the most common is 60 minutes. I know their is a version that gives up to 120 minutes for ETOPS AC.
You dig the hole .. I fill the hole . 100% employment !
B727 From United States of America, joined Oct 1999, 509 posts, RR: 2 Reply 11, posted (6 years 2 weeks 4 days 16 hours ago) and read 3033 times:
Pretty much what TriStar Steve descried is correct. Back 7-8 years ago I worked as a Fire suppression Technician. Most were set for the 30 minute activation. He is correct, that once you chose forward or rear compartment, you can not change to the other. The systems that I have worked on are Fenwall, Ansul, and Afex. Most aircraft de-icers have a built in system as well, to protect the unit from the on board glycol heater/burner. The units that I worked on had a gas fired burner.
HAWK21M From India, joined Jan 2001, 30166 posts, RR: 61 Reply 12, posted (5 years 5 months 1 week 6 days 18 hours ago) and read 2748 times:
Quoting MarkHKG (Reply 9): Which would do little if, for some reason, the fire was caused by improperly packaged chemical oxygen generators that activated accidentally in the hold
KPIE172 From United States of America, joined Nov 2006, 20 posts, RR: 0 Reply 13, posted (5 years 5 months 1 week 6 days 17 hours ago) and read 2724 times:
Sad to think that during a false alarm any pets down there are gone at the press of a button! Hey don't me wrong, I understand the importance of saying goodbye to Fido for the safety of many humans!
Just curious though... since the holds are designed to be somewhat robust is a visual inspection by a crew member possible in the event of an alarm warning with no other signs, ie. smoke, smell, etc.? Or are there no access points to the cargo holds (talking widebody here)?
ThrottleHold From South Africa, joined Jul 2006, 611 posts, RR: 1 Reply 14, posted (5 years 5 months 1 week 6 days 17 hours ago) and read 2723 times:
Discharging a fire extinguisher into a cargo compartment can result in the fire warning remaining permanently on. Therefore it may be difficult to know if it has gone out or not. Landing at the nearest suitable airport is the best course of action. Better safe than sorry!
Tod From Denmark, joined Aug 2004, 1597 posts, RR: 3 Reply 15, posted (5 years 5 months 1 week 6 days 16 hours ago) and read 2715 times:
Quoting KPIE172 (Reply 13): Or are there no access points to the cargo holds (talking widebody here)?
Most widebodies have an access hatch in the maindeck floor to access the e/e bay. From there, you can get a very limited glance at the top of the forward cargo compartment.
On 777 with a lower deck crewrest, you could kick open the decompression vent, but most likely it'd be up against another container and you would not be able to see anything so unless you got a face full of smoke or stink it probably would not help much.
AirframeAS From United States of America, joined Feb 2004, 12883 posts, RR: 30 Reply 16, posted (5 years 5 months 1 week 6 days 12 hours ago) and read 2678 times:
Cargo holds use a Systron-Donner type fire protection system or the Kidd Fire protection system using theromcouples. As far as extigusihing the fire in the cargo hold, I dont think there is really something that can be done other than landing the damn plane quickly.
A Safe Flight Begins With Quality Maintenance On The Ground.
Starlionblue From Greenland, joined Feb 2004, 15102 posts, RR: 69 Reply 17, posted (5 years 5 months 1 week 6 days 11 hours ago) and read 2662 times:
Quoting HAWK21M (Reply 12): Quoting MarkHKG (Reply 9):
Which would do little if, for some reason, the fire was caused by improperly packaged chemical oxygen generators that activated accidentally in the hold
Quoting KPIE172 (Reply 13): Sad to think that during a false alarm any pets down there are gone at the press of a button! Hey don't me wrong, I understand the importance of saying goodbye to Fido for the safety of many humans!
Good question. Anyone?
Tact Is For People Who Aren't Witty Enough To Be Sarcastic
FlyMatt2Bermud From United States of America, joined Jan 2006, 562 posts, RR: 9 Reply 18, posted (5 years 5 months 1 week 6 days 11 hours ago) and read 2662 times:
Quoting KPIE172 (Reply 13): Sad to think that during a false alarm any pets down there are gone at the press of a button!
I am not certain exposure to Halon, unless the agent comes in contact with direct flame, would be fatal to a dog under most circumstances. Best to follow the checklist and if there is no flame, your canine companion may survive the halon bath. I am not chemical expert and would appreciate further clarification.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward" Leonardo Da Vinci
Fokker Lover From , joined Dec 1969, posts, RR: Reply 19, posted (5 years 5 months 1 week 6 days 10 hours ago) and read 2651 times:
Quoting FlyMatt2Bermud (Reply 18): I am not certain exposure to Halon, unless the agent comes in contact with direct flame, would be fatal to a dog under most circumstances. Best to follow the checklist and if there is no flame, your canine companion may survive the halon bath. I am not chemical expert and would appreciate further clarification.
Halon displaces oxygen. All living things would suffocate. My airline policy is to no longer carry live animals in the cargo bin. If it won't fit in a small cage under your seat, it doesn't go.
Quoting TristarSteve (Reply 7): On the B737-2/3/4/500 and many other similar era aircraft the sealed freight hold is all there is to put the fire out. The design case relies on the fire running out of oxygen in the hold!!!
As a result of the Valujet incident an AD was issued. We modified all of our 737's to ad fire supression. As AGM100 stated above, it's a safe bet that all part 121 carriers have fire supression.
The Airbuses and newer stuff were designed with rubber seals between the cargo panels. Our older stuff, (like 737's) have fire resistant cargo pit tape on all of the joints and seams. They are airtight. We will no longer work inside of a cargo bin with the doors closed. If there was an accidental discharge, there would be no getting out.
EMBQA From United States of America, joined Oct 2003, 9177 posts, RR: 14 Reply 20, posted (5 years 5 months 1 week 6 days 9 hours ago) and read 2629 times:
No, you can not depressurize only the cargo hold. Most commercial airfcraft have a fast discharge fire bottle and one slow discharge fire bottle. The fast discharge bottle floods the compartment with one fast blast of Halon. The slow discharge bottle slowly discharges the bottle over 20-30 minutes to assure no 'flare-up' Halon removes all oxygen from the compartment and snuffs out the fire. The size of the bottle is driven by the size of the compartment, but as an average most that I deal with are bigger then a basketball, smaller then a beachball and weigh about 25-30lbs.
"It's not the size of the dog in the fight, but the size of the fight in the dog"
AAR90 From United States of America, joined Jan 2000, 3342 posts, RR: 51 Reply 21, posted (5 years 5 months 1 week 6 days 8 hours ago) and read 2618 times:
USA FAR-121 carriers are required to have cargo fire detection and protection systems. Most narrowbody aircraft are/were designed with Class-D cargo compartments (almost, but not quite air-tight) to "contain" a fire (not necessarily put it out). With the addition of a fire protection system most fires will be extinguished by activation of the fire protection system. Exact system components are airline/aircraft specific.
AA MD80/738 aircraft utilize Class-D cargo bins with redundant smoke detection systems and one (or more) halon protection systems. As with engine fire detection systems, the cargo detection system requires both redundant detectors to signal too much smoke at the same time to activate the cargo fire alarm. Pilots then select the alerted cargo bin on the fire protection system and then activate the halon bottle. Lastly (and it won't take very long to get to this point) is to land the plane A.S.A.P.
*NO CARRIER* -- A Naval Aviator's worst nightmare!
Srbmod From United States of America, joined Mar 2001, 16223 posts, RR: 57 Reply 23, posted (5 years 5 months 1 week 4 days 14 hours ago) and read 2468 times:
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Quoting Fokker Lover (Reply 19): As a result of the Valujet incident an AD was issued. We modified all of our 737's to ad fire supression. As AGM100 stated above, it's a safe bet that all part 121 carriers have fire supression.
If I had a dollar for every time I hit my head on the retrofitted fire supression equipment on FL's DC-9s...... I nearly knocked my self out on several occasions, as they hung from the ceiling of the cargo bin (Most are somewhat flush with the ceiling). One day, I did it twice in a matter of minutes loading the same a/c.
Hello Airplanes? Yeah, it's Blimps. You win, bye....
AirframeAS From United States of America, joined Feb 2004, 12883 posts, RR: 30 Reply 24, posted (5 years 5 months 1 week 4 days 5 hours ago) and read 2407 times:
Quoting AAR90 (Reply 21): cargo fire detection and protection systems
With either the Systron Donner type or Kidd type systems.
A Safe Flight Begins With Quality Maintenance On The Ground.
25 57AZ: Correct. Many buildings also have halon extinguishers in areas where computer servers/banks are present. I remember when I worked as a security guard
26 MarkHKG: It's more of a risk if it is a carbon dioxide system, rather than a halon system. I've heard of Carbon dioxide system killing people (mostly during ac
27 Speedracer1407: Sad indeed. Off topic, but I wonder how the law (at least in the US) deals with something like this. My dog, a Siberian Husky, is my friend and compa
28 Starlionblue: My guess is you would get compensation (through lawsuit or agreement). But "the needs of the many outweigh the needs of the few, or the one". Huskies
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