Inflight Fires

Inflight Fires Technicians, be on the lookout for potential fire dangers By Stephen P. Prentice Happy New Year . . . or so the saying goes. Every time New Year's rolls around I am reminded of a tragic accident involving a famous singer and...


Stephen P. PrenticeHappy New Year . . . or so the saying goes. Every time New Year's rolls around I am reminded of a tragic accident involving a famous singer and bandleader. You all probably remember him but you may not recall how he died. This accident did not have to happen and my goal is to frequently remind all technicians to be on the lookout for potential fire dangers in every aircraft they work on. I have addressed this subject in the past and consider it important enough to repeat from time to time. Without a doubt, in-flight fires are the most feared and dangerous incidents bar none. Even the dangers of engine power loss pales when we talk about in-flight fires.

The accident

His name was Ricky Nelson and on New Year's Eve, December 31, 1985, his lumbering old DC-3 cruised serenely through the early evening sky toward another nightclub engagement in Dallas, TX.

The aircraft was a modernized DC-3 that had been converted from a surplus C-47 many years before and was in good shape.

Ricky's band had just left an engagement in Alabama and was looking forward to seeing the brighter lights of Big D. It was cold even though they were only cruising at 6,000 feet. The captain was asked to turn up the heat. This particular aircraft was outfitted with a gas combustion heater in the tail of the aircraft behind the cargo area. The unit had been somewhat erratic in its operation and had been worked on at an FBO only a few weeks before. The fact that it refused to light was not a surprise to the crew.

Now, we all know about gas combustion heaters and how dangerous they can be. These units have many systems to ensure their proper and safe operation but this only means that they are prone to be high maintenance items. This one was no exception. The history of gas combustion heaters is long and tortured with many accidents. When they work they are great, but as we all know they are dangerous when not properly maintained.

Back to the story. Wisps of smoke were first noticed by the band members in the passenger compartment near the aft cargo storage area. That's where the heater was also located. They called the captain and asked him to come back and investigate. As he was checking it out the smoke increased and soon was dangerous. The captain discharged a fire extinguisher into what he thought was the source of the smoke and secured the access door. He reported seeing no visible flames at that time.

The captain returned to the flight deck and immediately called ATC and requested a vector to the nearest airport. This was to be Texarkana some 40 miles behind them. Seconds later the captain reported to ATC that he had smoke in the cockpit now and that he was making an immediate descent. There was still enough twilight to spot an open field and they made a gear down emergency landing in a farmer's field. They came to rest in a clump of trees after taking down a small pole and some wires.

The crew crawled out their respective side windows and fell the 12 feet or so to the ground. The co-pilot was barely conscious and the captain was in shock. One engine was still running when they came to a stop. The captain to his credit went immediately to the rear and opened the airstair door. He looked in as best he could and found nothing but smoke and flames. There were eight passengers, including Nelson. None survived even though the aircraft landed safely and intact. According to the reports they expired from the smoke and toxic gas in the passenger compartment. The subsequent advance of the fire destroyed most of the aircraft before emergency units arrived.

The total elapsed time from the first sightings of the wisps of smoke to impact with the ground was estimated at between 12 and 14 minutes. Keep in mind the ship was cruising at 6,000 feet, and it got down quickly and in one piece.

Lessons learned

This accident was tragic, but let's see what we can learn from it. Like many crash/fire accidents this one may have been survivable for the passengers had it not been for the toxic gases from burning plastics and, in particular, polyurethane foam. So the first thing to look at in any aircraft you work on is whether or not there is polyurethane foam anywhere in the aircraft. When polyurethane foam burns it produces hydrogen cyanide gas. This is the same stuff that was used in San Quentin executions for years. A whiff or two is enough to do you in!

Federal Air Regulations have in recent years been tightened up with regards to the flammability of the materials used in aircraft interiors. Many accident investigations have shown that passengers would have survived accidents were it not for the smoke and toxic fumes. The basic idea is to get the people out before they drop from smoke inhalation. Polyurethane materials are still permitted, in spite of their toxicity when burning, therefore it is useful to know if this material is present. If properly fire blocked it can be relatively safe for use. But remember, if fire gets to it the gas produced is lethal.

FARs

FAR 25.853 and Appendix F, Part II of Part 25 deal with most of the fire-related requirements. Take a look when you find the time. Air carriers are discussed in Parts 121.312 and 135.169. When you detect a recent interior replacement in an aircraft you are inspecting, you should check the aircraft records for the entries describing the job. Get the details of the installation. Find out about the materials used. Are they flame resistant or at least treated with compounds that aid in their resistance to burning? When in doubt about some material, see the supplier or contact your local FAA inspector. He can find out about materials easier than you can. In addition you have Designated Engineering Reps who are frequently involved with interior installations. Talk to them. They have the technical data to help define the proper procedures and materials that should be used. If there is any question, you can locate a sample of the material, put a match to it, and see how it supports combustion.

Examine interior installations

We all know that interiors are installed in many aircraft by automobile shops or furniture specialists who are generally not familiar with aircraft requirements. Also keep in mind that the FAR allows owners to install interiors. In this case you should ensure that an appropriate maintenance record is made and that the materials conform with FAR requirements. You could be held responsible if they do not conform.

As a licensed technician you have a duty to educate owners and operators about the dangers involved with fire-related accidents in both air carrier and general aviation activities. Owners and operators should be counseled on the finer points of selecting proper materials, and licensed technicians should see to it that they at least meet the minimum FAR requirements, if not higher air carrier standards. Remember, some day during a lawsuit you may be asked to show how you examined the installation during an inspection. Always look down the road and anticipate the worst.

Fire blocking of any polyurethane materials should be mandatory, keeping in mind the speed that it reaches its maximum toxicity when burning. Many newer foams on the market now have superior fire-resistant qualities although they are usually more expensive.

Many private and some air carrier aircraft still have substandard or non-approved interior materials installed. Any technician who performs an annual or other periodic inspection should take more than a casual look at any newly installed interiors. When you approve this aircraft for return to service, you have to be able to stand behind your statement that "this aircraft is airworthy". Therefore, you should examine the installation carefully for conformity with the rules.

New products

Fire-retardant products abound on the market today. So there is no excuse for not treating suspect materials.

All pilots should have access to a fire extinguisher in the cockpit. Passengers should also have one at their disposal. I can think of more than one accident where the lack of an extinguisher was a critical hazard. Rheostats get hot and cause burning in light fixture controls. (Cessna had trouble in this area.) Older radios and similar equipment produce heat sufficient to cause smoke and fire and ultimate destruction of the aircraft.

The lawsuit

Oh yes, a lawsuit did come about because of Ricky Nelson's accident. The technicians and repair station people who installed or had anything to do with the materials or interior installation all became defendants. In addition, the maintenance facilities that worked on the heater were also involved. And as usual, the last guys to put their hands on the heater took most of the heat. The case was settled on the day set for trial . . . five years after the crash! AMT

Stephen P. Prentice is an attorney whose practice involves FAA-NTSB issues. He has an Airframe and Powerplant certificate and is an ATP rated pilot. He worked with Western Airlines and the Allison Division of GMC in Latin America, servicing commercial and military overhaul activities and is a USAF veteran. E-mail:aerolaw@att.net

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