Although apparently hardly noticed by the press, the loss of a freighter B747-400F in September in Dubai set off alarm bells in the cargo world. Although the investigation is still ongoing, it appears that a fire in the cargo produced such volume and density of smoke that it completely blocked the vision of the two-man flight crew. Unable to even read their instruments or change radio frequencies, they they struggled back to near the airport only to crash. We should all extend our deepest condolences to the families of these brave airmen.
Fires on board aircraft are fortunately rare, but are one of the most feared events a crew can face. I have seen many overheated components and electrical black boxes, which literally cooked themselves and emitted noxious fumes and smoke. Bad wiring has been highlighted by the FAA, along with buildups of dirt and dust on wire runs. These just need a little heat to become the fuel for a fire. Even new aircraft, though, can have bad wiring from modifications. Witness the MD-11 passenger aircraft, which, 10 years previous to this cargo plane fire, plunged into the sea before the pilots could get it down. Faulty wiring was blamed.
How bad can smoke and fumes be? I was involved with one incident that, most fortunately, involved an aircraft just taxiing into the gate. The rampie marshalling the aircraft in was surprised to see the overboard vent for the electronic compartment start spewing thick black smoke and filaments of soot. He waved the aircraft to a stop and gave the “cut” sign. The black smoke changed to white steam and he wondered what was up.
The short story is that below the cockpit in the electronic compartment, an electric heater blanket around the lavatory dump valve had overheated, caught fire and set fire to the “fireproof” shroud around the lavatory waste tank. This in turn had ignited some of the ducting and insulation blankets under the floor overhead. The blower was taking the smoke and soot and throwing it out the overboard vent. The fire was on its way aft when a plastic water line running across the top of the compartment overheated and let go a shower that put out the fire. It also tripped off power.
With the blower off, the smoke and combustion products went upstairs, driving the flight crew out of the cockpit and stampeding the few remaining passengers and flight attendants off the aircraft. I was in my office and was called to the scene and arrived just slightly after the fire department. They were dragging one of my foremen off the aircraft. He had gone on board to try to open some doors and the brief exposure caused him to collapse. I had to borrow a breathing pack from the fire department to go on board. No live fire, the water line had done an efficient, but unplanned hit on it.
How bad was that smoke? I can’t speak for visibility, but everyone who breathed it was coughing and wheezing for a few days. The foreman spent a night in the hospital and sounded like an asthma victim when he came back to work. How hot was that fire? It warped floor beams and burned wiring bundles. What would have been the result if it happened in flight? I shudder to think.
Far more dangerous are the items taken on board the aircraft. Security has helped a lot here in preventing evidently daft people from bringing the most noxious things on board aircraft. Once, rampies were loading bags on a B727 when one that was being stacked in the hold started smoking and emitting nasty fumes. The fire department removed it to find an idiot chemist was transporting a bottle of concentrated acid. The stopper came loose under the gentle ministrations of the handlers.
Isolated case? Not really. A few months later I was walking to my office located out in the departure wing when I noticed a 20-foot trail of small holes progressively growing in size to culminate in a large bare patch with singed borders. Yes, another daft chemist with a bottle of concentrated nitric acid in his carry-on bag. No evil intent, just rampant stupidity.
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