View Full Version : Inert gas fuel system too expensive - task force.

Cyclic Hotline
9th Aug 2001, 03:40
Panel says air fuel tank measure too expensive

WASHINGTON, Aug 8 (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.


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. (BA.N) 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.


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.

Squawk 8888
9th Aug 2001, 07:01
Given the rarity of inflight fuel-tank fires, if those cost estimates are accurate then a helluva lot more lives could be saved if that kind of money were invested elsewhere.

Just curious- I'm wondering why Explosafe technology (around since the 70s) hasn't been tried- it's simple, cheap and relatively maintenance-free. In a nutshell, it's a metal mesh inside the tank that dissipates heat pretty quickly- I saw a demo where a half-full jerry can had a flame burning in the spout like a candle. Won't prevent ignition, but does prevent explosions and slows the spread fuel fires. Was it proven less effective than the original claims, or was there some other reason?

9th Aug 2001, 08:47
I think the NTSB are right to question the figures - they are clearly nonsense.

It would cost the industry very much more than a mere US$21 billion to inert every fuel tank in every aircraft AND provide the necessary infrastructure at every airport. We're talking about a hell of a lot of nitrogen here, not to mention an extra couple of thousand kilogrammes added to the weight of every aircraft. And what would the environmentalists have to say about it if it ever happened? We've already had to trash-can the most effective fire extinguishant available because of environmental concerns.

Nope, its not on and never was...

Through difficulties to the cinema

Flight Safety
9th Aug 2001, 09:56
Just my two cents worth. The article reads in part:

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.

Why is this?

The medical community has a technology available that uses an electrical means of separating the oxygen and nitrogen in normal air, and it's used to supply oxygen to patients. The units I've seen for a single patient are small (about the size and shape of a canister vacuum cleaner) and roll on wheels and plug in a normal electrical outlet just like a vacuum cleaner. The units have that typical green clear plastic tube for the oxygen outlet.

An aviation unit of this type (call it an "electric nitrogen generator") could produce a continuous supply of nitrogen using the same technology. I'm sure the process does not produce "pure" nitrogen, but the oxygen content might be low enough to provide effective fuel tank inerting. A system of this type with generator and lines, could be both light weight and very low maintenance, and perhaps not very expensive.

As a side benefit, the generator could be used to supply supplimental oxygen to the flight crew during a decompression event.