Some bureaucrats at the Federal Aviation Administration (FAA) are good at tooting their own horns in the face of overwhelming and continuing vulnerability. A case in point is an FAA Technical Center document dated May 2011.
Technical Center logo
This technical note (DOT/FAA/AR-TN11/8) is grandly titled, “Improvements in Aircraft Fire Safety Derived From FAA Research Over the Last Decade”. The reality is that the research has been selective and has not as of yet resulted in a whole scale improvement in the nation’s fleet of airliners. Passenger and cargo-carrying aircraft remain flying firetraps. Unlike public buildings, such as offices, schools, hospitals, nursing homes and the like, which are required by building codes to be 100% covered by fire detection and suppression, an airliner has entire areas bereft of fire detection and suppression, despite the fact that airplane occupants are stuck in their seats until an on-fire airplane lands. In this respect, passengers are analogous to nursing home occupants – aged patients with limited mobility, often confined to wheelchairs. The inability of nursing home occupants to quickly evacuate a burning building is a major reason for full detection and suppression of fires. Passengers do not benefit from similar protection, despite the fact that the aircraft is a mobile life support system from which immediate escape is not possible.
One could argue that the results of the Technical Center’s efforts are paltry. The TechCenter asserts that its fire safety research during the period from 2000 to 2010 has:
“[Resulted] in the adoption/issuance of five final regulations, two Airworthiness Directives, two Advisory Circulars, and two Safety Alerts for Operators, which are expected to significantly improve aircraft fire safety.”
This assertion may sound like a very productive effort. However, only regulations and Airworthiness Directives (ADs) are mandatory. Everything else is advisory, for information, and definitely not required.
If one looks only at the seven mandatory actions, these actions are the equivalent of approximately one regulatory action or required corrective action every 1.5 years. Regarding these various mandated initiatives, some of the most important have had no effect on the fleet of aircraft because of their generous implementation time. For example, one of the touted mandatory actions concerns fuel tank inerting – or the provision of explosion-suppressing gas into the void spaces of fuel tanks. This inerting program is intended to prevent a recurrence of a TWA Flight 800 disaster, in which the flammable ullage (vapors) in the center wing tank of an older B747-100 was ignited by electrical arcing of fuel quantity indication system (FQIS) wires inside the tank. The resulting catastrophic explosion shortly after takeoff from New York’s Kennedy International Airport blew apart the airplane and killed all 230 persons aboard.
In the July 2008 Federal Register, the FAA published a final rule requiring new and existing airliners to be fitted with either a Flammability Reduction Means (FRM), which is generally understood to mean an inerting gas inside the fuel tank, or an Ignition Mitigation Means (IMM). An IMM can be foam block in the tank to reduce or contain an ignition source, preventing an explosion and thereby accomplishing the same end as inerting.
Either FRM or IMM must be installed on new aircraft within two years, placing the deadline in July 2010. The number of new airliners entering service is paltry compared to the size of the existing fleet: approximately 100 new aircraft compared to an existing fleet of some 4,000 jets.
For the existing fleet, the FAA has allowed planes to operate without retrofit until 2018 – fully 22 years after TWA 800 exploded.
The TechCenter takes credit for a rule that should have been published years ago and, in fact, published well before TWA 800 blew up, as the hazard has long been recognized and systems have been developed to mitigate it. The record demonstrates that at least three generations of inerting technology were not deployed on airliners because of the absence of an FAA requirement to do so:
1st generation: 1950, an inerting system was fitted to the first jet bomber, the B-47, based on filling canisters in the wheel wells with dry ice (CO2). The ice was heated, and the resulting CO2 gas was piped to the fuel tanks.
2nd generation: 1970, the FAA successfully demonstrated a liquid nitrogen (LN) based inerting system in a DC-9 aircraft.
3rd generation: 1983, Boeing patented a membrane-based technology to produce nitrogen-enriched air (NEA) to inert fuel tanks.
The technology mandated by the FAA is a pared down version of the 3rd generation system. A vacuum bottle, used originally, to store NEA for the descent phase of flight has been eliminated. The bottle was used to store surplus NEA produced during cruise, which would then be metered to the fuel tanks during descent. With the vacuum bottle removed (as a weight saving measure), the new system will not provide inerting during descent.
The inerting system developed by the TechCenter, which basically is a stripped down version of Boeing's patented system. The arrangement shown here lacks an oxygen sensor to ensure that the fuel tank is in fact inerted.
This rule addresses only heated center wing tanks, the type which exploded on TWA 800. Airplanes with unheated center wing tanks or no center tanks are not affected. A heated center wing (e.g., fuselage) tank is one in which nearby equipment generates heat which, in turn, can migrate into the center wing tank, thereby elevating the temperature of the ullage into the flammable range. A spark from fuel pumps, fuel quantity, or other electrical systems internal to the tank can ignite flammable vapors.
The National Transportation Safety Board (NTSB) did not make a distinction between unheated and heated, or between center or other tanks. The NTSB recommended that all fuel tanks be inerted.
The NTSB complained to the FAA about the unavailability of inerting on all aircraft regardless of whether or not they have heated center wing tanks. For example, in its 2004 protest over the intended Airbus A380 super-jumbo jet design, the NTSB said:
“The draft SC [Special Condition] is … based on a philosophy that accepts fuel tank flammability, proposes that safety assessments be performed to demonstrate that the presence of an ignition source within the fuel system is ‘extremely improbable’, and describes the operation of a new transport airplane with a flammable fuel/air mixture in the fuel tanks.”
Despite this complaint, the European Aviation Safety Agency (EASA) certified the A380, as did the FAA.
It gets worse. The inerting rule completely ignores safety margins. For example, the FAA considers the fuel tank to be explosive only after the fuel vapor concentration exceeds 100% of the Lower Flammability Limit (LFL), as opposed to the 25% limit adopted by the National Fire Protection Association.
The FAA assumed that if the ullage had an oxygen concentration restricted to 12% then the tank would effectively be inerted. Traditionally, an oxygen content of 9% has been used, which provides a safety margin. The FAA determined that an inerting system capable of reducing the oxygen content of the ullage to less than 12% is “impractical for commercial airplanes” since a more capable inerting system would be needed.
There are other deficiencies in the final rule on inerting. Suffice it to say, the FAA has opted for a minimalist approach to inerting which eliminates all safety margins.
The TechCenter takes credit for having influenced this travesty of a rule.
What did the TechCenter not do? It failed to address why fuel tanks were, and are, designed with all sorts of electrical components inside the tanks, such as electric fuel pumps, electric fuel quantity measuring systems, and the routing of wires for other systems inside fuel tanks. The density of electrical systems inside fuel tanks invites the probability of failure (e.g., chafing) and the likelihood of an errant spark.
It would have been more fruitful for the TechCenter to explore alternate designs in which fuel tanks did not contain any electrical components, thereby providing a design template for aircraft manufacturers to emulate.
To be noted, the TechCenter did perform useful work by demonstrating the flammability of insulation blankets covered in metalized Mylar.
Photographs compiled by the TechCenter showing damage resulting from a hidden in-flight fire involving insulation blankets.
All such insulation material was removed from about 800 airliners as a result of the TechCenter’s research. Again, consider what the center has not done — it has not tested new, absolutely flameproof insulation material. Called Starlite by its manufacturer, it is superior to even the most dramatic insulation on the Space Shuttle. A Boeing official said:
“We coated an egg with a layer of [the] material about the thickness of peanut butter you’d put on a sandwich, then we put a blowtorch to it for a couple minutes until it glowed red. Immediately after the flame was removed, you could hold the egg in your hand, and when we broke the egg open it was still raw. We see the possibility of preventing injuries and death during aircraft ground fires with this material.”
Not to mention that the material, substituted for existing insulation blankets on an airplane, would enhance safety during in-flight fires as well.
Maybe the fact that this the material is the invention of a former hairdresser, not of an aerospace scientist, is part of the reluctance to accord Starlite due deference for its flame proof properties. That, and the reluctance of the inventor to divulge the exact chemical make-up of Starlite. In any event, it has not been subjected to high profile tests by the TechCenter.
The TechCenter did test a device in which a hand-held fire extinguisher could have its chemicals get behind a cabin ceiling. The Swissair Flight 111 aircraft, an MD-11, which crashed in Halifax, Canada, in 1998, was downed by a fire in the so-called attic space above the cabin ceiling panels. One company has developed a port, affixed to interior cabin panels, in which an extinguishing agent could be squirted into the area behind. The TechCenter gave the device lukewarm marks:
“A preliminary series of tests were conducted to examine the use of ports, opening in the cabin ceiling, to allow the discharge of Halon 1211 hand-held extinguishers into the attic area. Not surprisingly, it was shown that the ports could be effective in the relatively small volume that exists in a standard-body aircraft (e.g., a B737 or A320); but in a wide-body aircraft (e.g., a B747), this approach would not be effective because the agent is diluted by the large volume of the attic area. Additionally, to make the ports practical and effective in a standard-body aircraft, a detection system would be needed to locate the fire, and the ports would have to be spaced to optimize the effectiveness of the available extinguisher.”
What is not mentioned is that after the crash in Canada, Swissair installed infrared cameras in the attic space of its remaining MD-11s, with the pictures piped to a display in the cockpit. The problem of locating a hidden fire was effectively solved.
The problem of attic space conflagrations is only a part of the hidden fire problem in which access ports would be useful. The TechCenter report does not mention that behind cabin sidewalls electrical components proliferate. A series of ports along the cabin would facilitate the application of fire suppressant chemicals in a confined area where the chemicals would not be diluted by space.
The TechCenter report also fails to address the problem of smoke in the cabin and cockpit. Regarding smoke in the cabin, one manufacturer has developed a combination oxygen mask/smoke hood which would drop from the overhead instead of the “little yellow cups” which constitute the current passenger emergency oxygen mask.
The combination mask/hood would not only provide exygen, but would also protect the passenger from heat and the noxious effects of smoke. When it would be time to evacuate the airplane, the hood would break away from its oxygen umbilical and the passenger would have sufficient breathable air to evacuate the airplane.
With nil interest from the aviation industry, the manufacturer has suspended further development and marketing of the combination mask/hood. The U.S. military has not accepted this state of affairs. All military transports are equipped with portable breathing equipment (PBE) for passengers and crew. The PBE weights about 1 lb and can keep the wearer alive for up to an hour. This safety device is also used on many civil passenger planes, but is only available for the crew.
Smoke in the cockpit can be countered by oxygen masks and goggles worn in emergencies by the pilots. However, the presence of thick, blinding smoke can obscure instruments and the view out of the windscreen. In the Canadian report of the Swissair disaster, it was surmised the pilots had trouble seeing their instruments and therefore standby gauges and displays should be larger. In the presence of pervasive smoke, goggles are of no use beyond the short distance from eyeball to faceplate, and the size of the instruments is of no help. If the pilots cannot see out the windscreen, how are they supposed to land the airplane? A device known as EVAS (Emergency Vision Assurance System) features an inflatable, clear plastic bubble which physically displaces the smoke, giving the pilot a reduced view of instruments and a forward view out of the windscreen.
EVAS deployed from its briefcase-size box and in action.
This technology has not been tested or endorsed by the TechCenter. However, the FAA has equipped its own airplanes with this safety device, and it has approved installation on airplanes when applicants have asked for it. So now we have the FAA preaching “one level of safety”, with a higher standard for its own airplanes than for those of the flying public.
An example of the cockpit visibility problem comes from the September 2010 crash in the United Arab Emirates (UAE) of a United Parcel ervice (UPS) B747-400 freighter.
Crash scene of a UPS B747 freighter near Dubai
With a fire on the main cargo deck, the cockpit quickly filled with smoke. According to the preliminary report by the UAE’s General Civil Aviation Authority (GCAA):
“The crew informed BAH-C [Bahrain Air Traffic Control] that there was smoke in the cockpit and that the ability of the crew to view the primary flight instruments and radio frequency selection controls had become degraded …
“Based on the information available to date, it is likely that less than 5 minutes after the fire indication on the main deck, smoke had entered the flight deck and intermittently degraded the visibility to the extent that the flight instruments could not be effectively monitored by the crew.”
From the GCAA preliminary report
The crew was killed while attempting an emergency landing. Since the accident, UPS has ordered EVAS for its entire fleet.
A tantalizing — and chilling — statistic is contained in the TechCenter report: in 2006 there were more than 800 incidents of smoke or odor in the cabin or cockpit. In 34% of cases, the severity was such that the pilots diverted the aircraft to a quick landing or returned hastily to the departure airport. This works out to one incident every day for nine months. Yet smoke hoods and emergency vision for the pilots remain unexplored territory at the TechCenter.
Above all, the TechCenter has not undertaken a vigorous research program into one of the fundamental recommendations coming out of the Swissair 111 disaster. The Transportation Safety Board (TSB) of Canada, who investigated the crash, stated that if there were no flammable materials used in the construction and equipping of airliners, the danger of airborne fire would be greatly reduced.
A technical inquiry into such feasibility has not been undertaken.
Rather, research remains focused on various tactical problems, such as the vulnerability of certain types of insulation blankets to ignition from adjacent fire, or reducing fuel tank vulnerability to explosion. Promising technologies seem to be ignored and basic issues – such as electrical components routed inside fuel tanks – are not questioned.
As the TechCenter report freely notes, three crashes were major stimulants of its work:
1. The 1996 loss of a ValuJet DC-9 due to an uncontrolled fire in its foward belly hold, with the loss of 110 lives when the airplane plummeted into the muck of the Florida Everglades. Before the crash, there was smoke in the cockpit.
2. The 1996 destruction of the TWA B747 due to the explosion of flammable vapors in a fuel tank, with 230 fatalities resulting.
3. The 1998 loss of a Swissair MD-11 due to an uncontrolled fire in the attac space, with 229 fatalities. Before the crash, there was smoke in the cockpit.
Without these crashes, it is doubtful that the TechCenter would have undertaken the modest research program it did perform, looking into fire aboard airplanes. In other words, without the grim stimulus of three crashed airplanes and 569 lives lost, the belated and weak research program which was undertaken might not have been conducted.
The FAA is often accused of taking a “tombstone” approach to air safety, which means the agency is only galvanized by disaster to take action. The TechCenter report provides further evidence of this approach; and the report, with all of its self-proclaimed accomplishments, still evades basic issues, such as electrical system routing, flammable materials, and new technologies.
Indeed, the TechCenter report could be compared to one completing his/her own report card. The center gives itself an “A” for contributing effort — one required action every 1.5 years.
A knowledgeable third party might be less generous – maybe a gentleman’s “C” for doing just the basics – after hundreds of lives were unnecessarily lost.