(check link at the page bottom for the real; cause of TWA800)

 
Wednesday August 8, 6:40 pm Eastern Time
Panel says air fuel tank measure too expensive 

(UPDATE: adds NTSB comment, background on fuel tanks paragraphs 2, 10-11, 22)

By John Crawley WASHINGTON, Aug 8 2001 (Reuters) - A task force said on Wednesday it found that the use of inert or nonflammable gases in airline fuel tanks to help prevent explosions such as the one that brought down TWA Flight 800 was impractical and too expensive to implement in the near future.

The findings prompted renewed concern from disappointed U.S. safety investigators, who said efforts to prevent fuel tank explosions since the 1996 TWA jumbo jet crash that killed 230 people have not gone far enough.

After a year of study, the task force submitted its report to a Federal Aviation Administration advisory panel, which questioned some of the findings at a public hearing.

While the task force of experts from the aviation industry and other fields, as well as public interest groups, did not embrace the injection of inert gases to reduce the amount of air in fuel tanks, it said more study could yield a way to do it effectively, safely and more cheaply.

The FAA advisory committee, made up of industry and government officials and labor and consumer group representatives, ordered a 90-day review period before it would hold a final vote in November on whether to recommend the task force's findings to the FAA.

Two members of the advisory panel expressed fundamental reservations with the task force's findings.

``As it stands, I don't think it will have credibility,'' Paul Hudson, a committee member and executive director of the Aviation Consumer Action Project, said of the study.

PRICE TAG: $10 BILLION TO $21 BILLION Hudson, the most outspoken of the study's critics, said he doubted calculations that developing and using inert technology could cost the aviation industry between $10 billion and $21 billion from 2005 to 2020.

He questioned whether the aviation industry, because of its major influence on the task force, played an unfair role in determining the bottom-line figures. ``The costs are inflated,'' Hudson said at the hearing.

The National Transportation Safety Board also singled out the cost calculations for criticism.

``I am disappointed that their cost-benefit analysis leads them not to recommend inerting systems,'' Carol Carmody, the acting safety board chairman, said in a statement. ``We question the factual basis for the cost-benefit analysis.'' Task force co-chairman Bradford Moravec backed the analysis. ``We tried to get the best expertise we could,'' he said. ``I didn't feel this was a bunch of amateurs looking at this.'' The study is considered a benchmark for consideration of new federal rules on fuel tank safety.

Two TWA explosion and other airline fuel tank blasts involving foreign-operated Boeing Co. (NYSE:BA - news) 737 aircraft on the ground since 1990 also prompted closer scrutiny as well as industry and regulatory steps to avert future incidents.

Under regulations mandating the use of inert gases, aircraft manufacturers and airlines would have to find ways to redesign or modify fuel tanks and their systems. The changes would apply to airliners already in service, in or scheduled for production, or on the drawing board. Airports would have to make infrastructure changes to accommodate a new system.

OTHER STEPS ON FUEL TANK SAFETY

FAA spokeswoman Alison Duquette said the task force recommendation was only one factor the agency will weigh in considering whether to adopt a new rule.

Since the TWA disaster, aviation regulators have issued more than 40 mandates to prevent ignition sources in airliner fuel tanks. Those actions cover a wide range of aircraft, including the 747 and the popular 737 series aircraft.

The NTSB determined that Flight 800 was most likely destroyed by a center-fuel tank explosion shortly after takeoff from New York. While no firm conclusion was made on what triggered the blast, safety board investigators believe a wiring problem was to blame.

The safety board believes the FAA and the industry should take additional steps to further reduce the chance of an explosion by embracing the use of inert gas, like nitrogen, to eliminate air in fuel tanks.

But the task force said it could not find design concepts for ground-based or on-board systems that met regulations or provided a reasonable benefit for the money it would take.

An FAA regulation issued in May requiring aircraft manufacturers to review fuel tank system designs and airlines to develop new fuel tank maintenance strategies could affect up to 7,000 planes and cost the industry as much as $170 million.

But the NTSB said despite the aviation community's efforts so far, there is no way to be sure that all possible ignition sources have been eliminated. ``The safety board strongly believes that near-term measures to eliminate flammable fuel tank vapors are necessary and prudent,'' Carmody said. NTSB Advisory National Transportation Safety Board Washington, DC
20594 August 8, 2001 STATEMENT OF NTSB ACTING CHAIRMAN CAROL CARMODY ON ARAC REPORT ON AIRLINER FUEL TANK FLAMMABILITY A working group of an Aviation Rulemaking Advisory Committee, made up of airline industry and Federal Aviation Administration representatives, today submitted a report on its study of methods of dealing with airliner fuel tank flammability. The National Transportation Safety Board recommended in December 1996 both design and operational changes, following its finding that TWA flight 800 suffered a fuel tank explosion. Acting Chairman Carol Carmody today released the following statement in response to the working group report.

The working group's report clearly demonstrates the significant benefits to fuel tank safety and the consequent reduction in air transport fatalities provided by inerting. I am disappointed that their cost-benefit analysis leads them not to recommend inerting systems. We question the factual basis for the cost-benefit analysis presented in the report. I am pleased that the ARAC Executive Committee appears to share our concerns and has requested further clarification of that analysis.

This is an important issue, and the Safety Board recognizes that there may be a number of different ways to counteract fuel tank flammability in the existing fleet. Extensive research into the crash of TWA flight 800 revealed that dangerous conditions in fuel tanks occur more commonly than had been believed, and that there are numerous potential sources of energy to ignite fuel tank vapors. Despite the aviation community's best efforts, we can never be sure that all possible ignition sources have been eliminated. The Safety Board strongly believes that near-term measures to eliminate flammable fuel tank vapors are necessary and prudent.

The recent destruction of a Boeing 737 in Thailand shows that center fuel tank explosions continue to occur, and likely will occur again in the future. This problem must be addressed if we are to maintain the confidence of the traveling public.

- 30 -

NTSB Press Contact: Paul Schlamm (202) 314-6100
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Biased and Unfair

WASHINGTON -- Consumer and safety advocates Wednesday attacked an aviation industry report about fuel tank safety as ''biased and unfair.'' The report concluded that injecting non-flammable gas in jet fuel tanks to prevent explosions is too expensive. In a contentious meeting, the Federal Aviation Administration's advisory panel on the feasibility of requiring inert gas in fuel tanks voted to ''receive'' the report. Inert gases are non-flammable gases that prevent fuel vapors from exploding. The panel gave itself 90 days to decide whether the report needs to be changed.

Heated fuel tanks have exploded on three large passenger jets since 1990. On TWA Flight 800 in 1996, 230 people died when a 747 fuel tank blew up as the jet flew from New York to Paris. Nine others have died in explosions in Manila and Bangkok. In May, the FAA required improvements in aircraft fuel and electrical systems to reduce the chances of a spark reaching a tank. But the National Transportation Safety Board and other safety advocates have called for more steps to make the tanks less explosive. The FAA advisory panel, made up of industry, consumer and safety advocates, studied whether using inert gas in tanks would work. The report concluded that the costs of using inert gas ''far exceed'' the benefits. The industry-dominated group estimated that 132 to 253 lives worldwide would be lost over a 16-year span without using inert gas. However, using the gas would cost $7.2 billion to $11.1 billion over the same period.

The officials who presented the findings said the report represented a consensus of all participants. However, two members of the panel objected, and others are said to have reservations. ''I think the cost-benefit analysis is most biased and unfair,'' said panel member Paul Hudson of the Aviation Consumer Action Project.

Bernard Loeb, a former NTSB official who is not on the panel, agreed. He also said the design of some Boeing jets is inherently unsafe because the fuel tanks are heated by adjacent equipment. Those jets should be changed regardless of cost, he said. ''It's not a matter of whether there'll be another accident, it's a matter of when,'' Loeb said.

The acting chairwoman of the NTSB, Carol Carmody, also issued a statement criticizing the analysis.

The report's authors countered that they considered numerous assumptions in reaching their findings. ''We believe there's nothing there that would change our conclusions,'' said Bradford Moravec, a Boeing engineer who helped lead the group writing the report. The report urges regulators to seek other ways to make fuel tanks safer, primarily by reducing heat in the tanks. The panel is expected to provide the FAA with its final report by the end of the year. The FAA considers advisory reports but is not bound by them. 

Wednesday August 8 1:34 AM ET

Panel Won't Endorse Aircraft Fuel Tank Measure

WASHINGTON (Reuters) - A government task force is not expected to endorse the use of inert, or nonflammable gases in airline fuel tanks as a way to guard against explosions, a preventable step favored by U.S. safety experts but largely considered too costly by industry.

A source with knowledge of the highly controversial issue said late Tuesday the group was expected to present that conclusion in a draft report to a Federal Aviation Administration (news - web sites) advisory committee hearing Wednesday.

The recommendation against placing inert gas in fuel tanks is not binding, according to the agency, which refused to comment on what was expected to be a lengthy task force report.

However, a senior FAA official said the recommendation was only one factor the agency will weigh in considering whether to adopt a new rule. There is no timetable for a decision by the FAA, and more study is expected.

The issue stems from the explosion of TWA 800 five years ago off New York's Long Island. All 230 people aboard the jumbo jet were killed.

National Transportation Safety Board (news - web sites) investigators determined that the plane was most probably destroyed by a center-fuel tank explosion shortly after takeoff from New York in July 1996. While no firm conclusion was made on what triggered the blast, safety board investigators believe a wiring problem was to blame.

Two other airliner explosions in the past 10 years, both on the ground and both involving foreign-operated 737 aircraft, have been traced to fuel tanks.

Since the TWA disaster, aviation regulators have issued more than 40 mandates, including two this week, to prevent ignition sources in airliner fuel tanks. Those actions cover a wide range of aircraft, including the Boeing Co.'s 747 and the popular 737 series aircraft.

However, the safety board believes the FAA and the industry should take additional steps to further reduce the chance of any explosion by embracing the use of inert gas, like nitrogen, to reduce the amount of air in fuel tanks.

Airlines and the aircraft industry have signalled that the risk of explosion may be too small to justify the cost, which some estimate could be billions over several years.

An FAA regulation issued in May requiring aircraft manufacturers to review fuel tank system designs and airlines to develop new fuel tank maintenance strategies could affect up to 7,000 planes and cost the industry as much as $170 million.

August 9, 2001 - Safety Advocates Slam Industry Analysis Of Jet Fuel Tanks
WASHINGTON -- Consumer and safety advocates Wednesday attacked an aviation industry report about fuel tank safety as ''biased and unfair.'' The report concluded that injecting non-flammable gas in jet fuel tanks to prevent explosions is too expensive. In a contentious meeting, the Federal Aviation Administration's advisory panel on the feasibility of requiring inert gas in fuel tanks voted to ''receive'' the report. Inert gases are non-flammable gases that prevent fuel vapours from exploding. The panel gave itself 90 days to decide whether the report needs to be changed.

Heated fuel tanks have exploded on three large passenger jets since 1990. On TWA Flight 800 in 1996, 230 people died when a 747 fuel tank blew up as the jet flew from New York to Paris. Nine others have died in explosions in Manila and Bangkok. In May, the FAA required improvements in aircraft fuel and electrical systems to reduce the chances of a spark reaching a tank. But the National Transportation Safety Board and other safety advocates have called for more steps to make the tanks less explosive. The FAA advisory panel, made up of industry, consumer and safety advocates, studied whether using inert gas in tanks would work. The report concluded that the costs of using inert gas ''far exceed'' the benefits. The industry-dominated group estimated that 132 to 253 lives worldwide would be lost over a 16-year span without using inert gas. However, using the gas would cost $7.2 billion to $11.1 billion over the same period.

The officials who presented the findings said the report represented a consensus of all participants. However, two members of the panel objected, and others are said to have reservations. ''I think the cost-benefit analysis is most biased and unfair,'' said panel member Paul Hudson of the Aviation Consumer Action Project.

Bernard Loeb, a former NTSB official who is not on the panel, agreed. He also said the design of some Boeing jets is inherently unsafe because the fuel tanks are heated by adjacent equipment. Those jets should be changed regardless of cost, he said. ''It's not a matter of whether there'll be another accident, it's a matter of when,'' Loeb said.

The acting chairwoman of the NTSB, Carol Carmody, also issued a statement criticizing the analysis.

The report's authors countered that they considered numerous assumptions in reaching their findings. ''We believe there's nothing there that would change our conclusions,'' said Bradford Moravec, a Boeing engineer who helped lead the group writing the report. The report urges regulators to seek other ways to make fuel tanks safer, primarily by reducing heat in the tanks. The panel is expected to provide the FAA with its final report by the end of the year. The FAA considers advisory reports but is not bound by them. 
Arthur Alan Wolk: FAA Concludes an Occasional TWA 800 Repeat Crash Is Cost Effective

PHILADELPHIA, May 22 /PRNewswire/ -- The following was issued today by Arthur Alan Wolk of Wolk and Genter: In a stunning edition of a Special Federal Aviation Regulation (SFAR), the Federal Aviation Administration has concluded that it would be acceptable, from a cost standpoint, to accept another crash like TWA 800, rather than opt for a more expensive, but proven effective, fuel tank inerting system, reasoning that the cost of paying for lives lost and the aircraft would be cheaper than requiring a retrofit of a nitrogen based fuel tank inerting system that would guarantee no more fuel tank explosions.

In spite of a recent explosion of a Philippine Airlines 737 center fuel tank while the aircraft sat at the gate, an event Boeing and FAA officials argued was impossible, just like TWA 800, all the FAA has ordered is that each manufacturer of aircraft with more than thirty seats revalidate their fuel system certification analysis.

The FAA assumed that if it did nothing, there would be about five more fuel tank explosions in seventeen years. This calculation was made before the most recent that killed a flight attendant. The FAA went on to reason that if airlines keep the center fuel tanks fueled somewhat, and pilots don't run fuel pumps in a dry tank, about 4.3 of these accidents can be avoided -- leaving only .8 that are likely to occur. What that means is that if you are a passenger in a 350 seat airliner whose center fuel tank explodes, as you fall to earth, still alive in the fiery debris, you can rest assured that no other planeload of people as unfortunate as you will, statistically speaking, die the same way in the remaining portion of the seventeen years. Comforting, huh!

What is most remarkable about this abdication of responsibility is that statistical analysis of the risk was done by none other than the guys who certificated the airplanes' fuel systems as safe and who claimed that an explosion from such causes was impossible. The SFAR was in fact written with the help of none other than the plane makers and airlines who do not want to have to make a retrofit or design fuel inerting into new aircraft. In short, the foxes that guard the henhouse are responsible for the new rule.

Equally frightening is that in 1972, a test program funded by us taxpayers demonstrated that in a DC-9 aircraft fitted with a nitrogen inerting system, fuel system fires and explosions would be made impossible with such a system installed. The added weight, only 650 pounds! The system was found to work effectively and efficiently, yet nothing came of it to save the lives of over 230 innocent people in 1996 some 24 years later.

What mindset allows our Government to be so devoid of common sense and responsibility? The adage "Close enough for Government work" is the touchstone of FAA performance. Having found that manufacturers have failed to comply with the existing FAA regulations, the FAA, instead of making the airplanes safe and insisting on compliance, simply changed the regulations to save the industry money -- the same money that industry already saved by failing to meet the regulations in the first place. Arthur Alan Wolk

Having read that document in its entirety, I can offer some observations:
 
a.  The inspection and maintenance regimen should cover most (but not all) ignition potentialities (more on that below - see "IMHO").
 
b.  I couldn't really see anywhere my solution of utilising the entire fuel load as a capacious heatsink by continuously "through-putting" that whole fuel load over the high hazard periods (thereby resolving operation on the ground with CWT fuel at ullage levels on a hot day with onboard aircon operating). Even though some fuel manifold and transfer/scavenge/jettison pump modifications might be necessary, I think that the first priority must be to eliminate volatile vapour levels for JetA carriers in particular. Once you've done so, then random ignition sources assume only a secondary importance, yet you do get away from that single thread solution. Squirting Nitrogen into a tank in single-shot fashion would not necessarily ensure that, over an extended period, dissipation of that Nitrogen charge wouldn't allow the vapours to build up again (due to tech delays pre-start or ATC delays on the ground post-start).
 
c.  There seems to have been little discussion throughout the TWA800 saga about the virtues or benefits of fuel additives to raise auto-ignition flash-points (page 41). I would have thought that any improvements in this area could be achieved without loss of calorific value per unit mass of fuel. And every step in the right direction helps disproportionately. An alternative to adulterating the whole fuel load in this way might be (for "at risk" a/c) simply to add a physically immiscible heavier fraction of distillate to the CWT that would still be less dense than the Jet A, float on top of residual fuel and suppress Jet A vapours (much as a thin layer of oil floating on water stops evaporation). The quite small quantities involved would mix well via downstream filtration, when pumped into the wing-tanks, HP pump-sprayed and then atomised into the combustion chamber - and so should not unduly affect the normal power-plant combustion process.
 
IMHO the really insidious latent failure occurs in the unsupported lengths of wiring running inside conduits. The SFAR reporting talks in particular about aircraft with in excess of 50K hours increasingly having these wiring shorts inside conduits (Pages 18 & 24). The point is that you only need one of those to match up with an ullage-induced vapourous period (i.e. 30% of the operating time) and you have an explosion. These "inside conduit" failures cannot be picked up by inspection - although they could be eliminated by design. Intrusive inspections of inaccessible wiring are seemingly not mandated by this SFAR and are not planned (for recommendation) by ATSRACS. So why would a/c over 50K hours be demonstrating higher incidences of wiring chafing inside (and shorting to) conduits? Simply it is a function of the high frequency vibration over those numbers of flight hours. Everything on an airplane vibrates inflight but problems happen when two dissimilar materials, in close conjunction, vibrate at different harmonics and amplitudes over very extended periods. That is quite simply why wires wear inside conduits. In the past, AD's have called for wiring to be Teflon-sleeved or wrapped. Much of that conduit encased wiring would however be unprotected.
e.g. P58 ("arcing of pump power cables to the conduit.")
 
"Proposed §25.98l(c)(l) would require that the fuel tank installation include “a means to minimize the development of flammable vapors in the fuel tanks.”  Moreover, the FAA states that it intends that the body tanks “cool at a rate equivalent to that of a wing tank.” (Page 124). That may be OK for new designs but with inerting it simply won't happen. Stirring the fuel for throughputting between tanks would have this effect however.
 
The SFAR solution is to have a panoply of inspection-intensive design and maintenance fixes, individually determined for each type and taking up to 36 months to devise and implement AD's for. Simpler interim measures, according a much higher level of safety may be possible if the basic concept of heat-sinking the entire fuel load was combined with fuel additives - both to raise the flash-points and to "cloak" the flammable vapours.
 
Page References are to http://www.faa.gov/avr/arm/13782.doc

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