Suit over cabin air quality could change the industry Boeing and Honeywell are accused of knowing for years that design flaws in MD-80s and DC-9s let harmful chemicals into aircraft cabins

John Fowler, then chief of maintenance, ordered a mechanic to squirt 8 ounces of hydraulic fluid into a scooplike ''air inlet'' on the jet's underbelly, where it was sucked in by a small engine pumping fresh air into the passenger cabin.

In a few minutes, the managers noticed a waviness in the air inside the cabin that looked like automobile exhaust or a heat wave. ''I recall a metallic taste in my mouth, some burning around the eyes and sensitivity in my nose,'' Fowler would say later.

Fowler told his story recently during a trial that's been unfolding for 10 weeks in state superior court here. Twenty-six current and former Alaska Airlines flight attendants say they have suffered severe neurological damage from being repeatedly exposed to toxic chemicals on MD-80 flights during the 1980s and 1990s.

The case is expected to go to the jury this month, and the verdict could ripple well beyond Seattle, Alaska Airlines' hometown. A victory for the flight attendants could damage the public's confidence in the more than 1,700 MD-80s and DC-9s, the MD-80's predecessor model, used by airlines worldwide. It could also force airlines and aircraft makers to confront contaminated air problems that regularly turn up on other models. And it might stir further action to reduce the health risks for millions who fly, especially flight crews, young children and people sensitive to certain chemicals.

''This is a big environmental issue with serious consequences,'' says Jean Christophe Balouet, an environmental consultant based in Paris who has worked for flight crew unions in several countries. Airlines and aircraft makers, he says, have been ''reluctant to admit contamination takes place because they'd have to compensate the people who have been exposed.''

Last year, the Alaska flight attendants won a $725,000 out-of-court settlement from Alaska Airlines, and now they're going after two of the nation's biggest companies: Boeing and Honeywell.

The plaintiffs contend both companies have known for decades that the MD-80 and DC-9 have design flaws that make it easy for leaking chemical fluids to get sucked into the auxiliary power unit, or APU, and mix with cabin air. The APU is a small turbine engine used to generate electricity and circulate cabin air before takeoff.

Boeing inherited responsibility for the MD-80 and DC-9 models when it bought McDonnell Douglas in 1997. Honeywell owns AlliedSignal, which made the APU.

Both companies dispute the flight attendants' claims. They say fumes that enter the passenger cabin don't contain enough chemicals to cause harm. The lawsuit is believed to be the first to assert that an aircraft maker is responsible for the quality of the air breathed by passengers and airline crews. Jets built in the 1980s and since use 50% recirculated cabin air, instead of 100% outside air, as earlier models do.

Yet a wider group of people now routinely travel by air. In no other public venue can you find infants, the elderly and the infirm crammed into a public space -- with no exits -- and air supply systems in close proximity to pressurized lines of toxic chemicals.

Over the past decade, flight attendants, pilots and public-health advocates worldwide have clamored for air quality testing and standards. In a report to Congress in December, the National Academy of Sciences called for establishment of a surveillance program to monitor cabin air quality and document health effects.

''If people had half a clue about the possibility that this environment they're entering for whatever period of time could jeopardize them, they'd be up in arms,'' says former flight attendant Debra Bradford, the lead plaintiff.

To gauge how often air quality problems are reported on DC-9s and MD-80s, USA TODAY checked the Federal Aviation Administration's Service Difficulty Reports (SDRs) database. The FAA requires airlines to file the one-page documents each time a mechanical problem arises. They are an imperfect indicator because some airlines are more rigorous about filing them than others.

Even so, safety experts consider SDRs a useful tool for spotting industrywide problems.

From 1974 through mid-2001, eight U.S. carriers -- American, Northwest, TWA, Delta, Continental, US Airways, Midwest Express and Alaska -- reported 1,051 incidents of fumes, smoke, haze, mist or odors entering the cabin air supply system of DC-9s and MD-80s, USA TODAY found after reviewing SDRs supplied by Air Data Research of Helotes, Texas.

In a majority of the reports, the aircraft turned back to the gate or made an unscheduled landing. Typically, the air supply system was inspected, parts replaced and the jet returned to service.

The DC-9/MD-80 isn't the only model with cabin air problems. Through the 1990s, ''air quality incidents'' have been reported on Airbus 320s, Boeing DC-10s, 737s, 757s and the British Aerospace BAe 146, other airline maintenance records and union surveys of airline crews show.

In October, the British Air Line Pilots Association surveyed 93 crews who reported more than 1,600 events of fumes reaching the flight deck on Boeing 757s.

The events ranged from pilots ''noticing some smells'' and a few ''serious incidents where crews had to put on oxygen masks,'' says Bruce D'Ancey, assistant technical secretary for the union.

Honeywell and Boeing maintain that leaks, in general, occur so infrequently and pollutants mixing with cabin air are so minuscule that health risks are minimal.

''The level of (chemicals) that would enter the cabin environment in event of a leak is 1/1,000th to 1/10,000th of what would be required to even begin to be potentially harmful to human health,'' says Honeywell attorney Bradley Keller.

Though declining to comment specifically on the trial, Boeing provided a statement listing 11 studies purporting to show cabin air ''pollutant levels'' to be ''low and, in general, not different from ground-based environments such as your home or office.''

Medical experts say the right kind of research -- studies that analyze contaminated air, not just cabin air with no reported problems -- has yet to be done.

''Industry keeps saying there's no evidence that people have been hurt, but there's no evidence people have not been hurt either,'' says Christiaan van Netten, a professor at the University of British Columbia's Department of Health Care and Epidemiology.

''Basically, we don't know because we have yet to catch one of these incidents with the proper instruments.''

They begin with the placement of the APU's air inlet, the rectangular opening through which the unit draws in fresh air, in a ''6 o'clock'' position at the rear belly of the fuselage. Gordon and Elder contend that as McDonnell Douglas incorporated improvements to the 1960s-era DC-9, it should have heeded advice in a 1974 installation handbook suggesting the air inlet ought to be moved.

That's because hydraulic fluid lines running throughout the aircraft invariably leak fluid into the belly, which is designed with small ''weep'' holes so such fluid can drain out. Gravity and motion can draw fluid toward the rear belly, where the air inlet sucks it in like a vacuum. The APU then compresses the fluid and mixes it with air delivered into the plane's ventilation system.

''The least favorable location is an inlet located well aft of the bottom surface of the fuselage,'' the installation handbook warns. ''Fluids likely to be ingested with this type of inlet include those that may be spilled within the aircraft fuselage.''

SAE, a group that sets industrial standards for lubricants, reinforced that warning in a 1981 advisory: ''APU inlets should not be located on the bottom of the fuselage where there is maximum exposure to . . . fluid leakage.''

But it wasn't until after Boeing acquired McDonnell Douglas in 1997 that something was done. In 1999, more than a year after the Bradford lawsuit was filed, Boeing certified the latest version of the MD-80 and renamed it the Boeing 717, with one telling change: The APU air inlet was raised to one side, in the 2 o'clock position, of the fuselage, where it is unlikely to suck up leaking fluids.

Boeing officials testified that the air inlet was moved solely to meet stricter FAA ground noise rules. But Gordon and Elder contend Boeing moved the inlet to reduce future liabilities.

''Everyone knew the 6 o'clock location was prone to ingestion problems, so when the FAA said move it for noise, they had an excuse to do the right thing for the wrong reason,'' Gordon says.

The FAA in recent years has required airlines using DC-9s and MD-80s to install metal strips and drain tubes near the air inlet to help direct leaked fluids away from it. An FAA order in September 2000 makes reference to ''reports of smoke and odor . . . due to hydraulic fluid leaking in the APU inlet, and subsequently into the air conditioning system.'' The order requires airlines to strengthen hydraulic lines prone to cracking, ''which could result in smoke and odors in the passenger cabin or cockpit.''

When smoke or odor is reported on an American Airlines MD-80, the carrier removes the plane from service to conduct a ''burn-out'' procedure designed to remove all remnants of the leaked fluid from the air supply pumps and ducts. American has retrofitted its fleet of 360 MD-80s with higher-powered APUs and installed all available diverters and upgradeable ducting and fluid lines, says American spokesman John Hotard.

''We've built in a set of policies and procedures over the years to try to prevent fluid ingestion into the APU and odors in the cabin,'' Hotard says.

Gordon and Elder say the second design problem came to light in the 1980s when airlines began reporting an unexpectedly high number of premature APU removals because of chronic leaks of an internal oil seal, court records show. In 1995, AlliedSignal assigned an engineer, Arthur Eckstat, to try to resolve the problem.

Now retired, Eckstat testified that he discovered AlliedSignal had failed to adequately test the compatibility of a commonly used lubrication oil with a certain type of seal. The oil turned out to be more corrosive to that particular seal than anybody thought.

In August 1996, AlliedSignal began to call for airlines to switch to a compatible seal the next time they removed the APU for an overhaul. Karl Pfitzer, Honeywell's director of product safety and integrity, says most airlines, including Alaska, made the switch by 1998. ''We think it has been fully resolved,'' Pfitzer says.

But by then, APU seal leaks had plagued airlines for more than a decade, Gordon says. Incompatible seals and a poorly located air inlet, he says, combined to make the 1990s a decade when Alaska Airlines received about 1,600 reports of what the airline began calling ''unexplained illnesses'' from crew members and passengers. ''Mysteries are cheaper than fixes,'' he says.

Nixon lost her ability to multitask and, after the airline rejected her workers' compensation claim, was forced to go on welfare. She now works as a cocktail waitress and has trouble remembering things. ''I write all my orders down. You learn to cope.''

Karen Burns had been a flight attendant for eight years when she boarded a flight from Cabo San Lucas, Mexico, to Phoenix in July 1996. On the flight, she and two co-workers became seriously ill. Maintenance records show the MD-80 had leaked 8 quarts of hydraulic fluid.

For the next two years, Burns endured violent, involuntary jerking of her upper trunk and arms. Six years later, she still has occasional shakes and hasn't been back to work. ''As I start getting tired, I don't hold myself right, and it becomes more noticeable.''

She says she began coughing up blood and developed respiratory problems, memory lapses and chronic disorientation over the next three years. ''It's like Russian roulette for anybody who flies,'' Bradford says. ''You never know when your number is up.''

During the past 10 weeks, a dozen physicians and medical experts have testified for the plaintiffs that the flight attendants' central nervous systems have been damaged by exposure to organophosphates, a class of chemicals used in hydraulic fluid and jet engine lubrication oil. Organophosphates are used in pesticides and nerve gas.

Gordon has introduced evidence showing how the APU can superheat leaked fluids into a toxic ''chemical soup'' and how low concentrations of chemicals breathed on several different flights can, for some people, be more harmful than one large exposure.

Keller describes the plaintiffs as ''healthy people who live very active lifestyles.'' Toxicologist Carl Mackerer testified that a flight attendant could work in a ''visible mist environment'' for ''two hours a day, seven days a week, 52 weeks a year, for more than two years without sustaining . . . a delayed neurotoxic reaction.''

Plaintiffs' attorney Elder notes that even though Alaska, Honeywell and Boeing do not admit wrongdoing, each has taken steps to reduce opportunities for chemicals to mix with cabin air.

''They've probably solved the specific instance of seal incompatibility, but seals still sometimes leak, and the air inlet is still down there on the belly of the plane,'' Elder says. ''I think it happens less frequently than it used to -- but it still happens.''