Pressure vests worn by Air Force pilots on the F-22 Raptor have “an enormous failure rate” in tests, providing the “leading theory” behind incidents of oxygen deprivation, according to lawmakers briefed by the service.
“It appeared to be almost a unanimous failure rate in testing,” Representative Adam Kinzinger, an Illinois Republican and an Air National Guard pilot, said yesterday on a conference call with reporters.
Questions about the pressure vest provided the latest clue in a yearlong mystery over why Air Force pilots keep getting dizzy and disoriented flying Lockheed Martin Corp. (LMT:US)’s F-22. The vest, part of a “G suit” used to help pilots avoid blacking out during high-speed maneuvers, “increases the difficulty of pilot breathing under certain circumstances,” the Air Force said this week.
A Navy dive unit assisting in the Air Force’s continuing investigation found that all of the vests tested failed, according to a government official who was briefed on the matter. The results were preliminary and additional tests were to be conducted soon.
The pressure vest was designed and made for the F-15 fighter jet and has been adapted for use in the newer F-22, which was declared ready for combat in 2005, according to the official, who spoke on condition of anonymity because he wasn’t authorized to comment publicly.
About two dozen pilots and six ground-maintenance workers have reported symptoms associated with a lack of oxygen. There have been 11 reported incidents since the plane resumed flying operations last year after a four-month halt because of safety concerns.
Kinzinger called failure of the pressure vests “the leading theory at this point,” while saying it remains “just a theory.”
The pressure vest is made by Sewing Technology Inc., a closely held company based in Buffalo, New York, according to the Air Force.
“I do not believe that this vest would be contributing to this situation, as thousands of these vests have been worn and produced over the last 20-plus years without any concern that I am aware of,” Lisa Donhauser, a co-owner of the company, said in a written statement.
The hose and valve used on the vest are made by Gentex Corp., a closely held company based in Simpson, Pennsylvania, the Air Force said.
“Gentex is proactively responding to any information requests from the U.S. Air Force related to the F-22 program,” company spokeswoman Cheryl Fabrizi said in an e-mailed statement. She declined further comment, referring questions to the Air Force.
A majority of F-22 pilots surveyed early last year said they “did not feel confident” in the plane’s oxygen system, according to an Air Force response to questions submitted by Kinzinger and Senator Mark Warner, a Virginia Democrat. That finding contributed to the decision to halt flights last year, the service said.
Brigadier General Daniel Wyman, the Air Combat Command’s surgeon general, said in a June 11 interview that recent surveys showed pilots “are more confident than ever” in the plane.
Wyman and other Air Force officials have said the rate of oxygen-related symptoms is relatively low, with 11 unexplained incidents out of more than 12,000 sorties flown since the flight ban was lifted last year.
“We have pilots flying daily, and this isn’t happening to them,” Wyman said.
‘Come to Grips’
Warner and Kinzinger objected to that assessment yesterday. They cited Air Force data showing the hypoxia rate on the F-22 is more than 10 times that on any other Air Force aircraft.
There were 12.81 unexplained hypoxia incidents for every 100,000 flight-hours on the F-22, the data showed. The incident rate for all other planes was less than 0.4.
“It’s important for the Air Force to come to grips with these rates being high,” said Kinzinger.
Unable to explain symptoms of dizziness and a so-called Raptor cough, the Air Force has been looking at everything from the prosaic -- hoses, masks and pressure vests -- to the top- secret coatings and adhesives used in the plane’s radar- absorbing stealth skin that makes it harder to track.
After more than a year of study, the investigation has come up short of a solution.
“The bottom line is we don’t have a single causative factor,” Wyman said.
While the Air Force is investigating the pressure vest, the service hasn’t declared the mystery solved.
“The upper pressure garment is not ‘the’ cause of physiological incidents, and we still have other variables to work through before we can determine what the major factors are and how they interact to produce the number of unexplained incidents we’ve seen,” Lieutenant Colonel Edward Sholtis, an Air Combat Command spokesman, said in an e-mailed statement.
With the answer still elusive, Warner, who cited the “enormous failure rate” of the vests in testing, said, “We may end up finding it’s a series of factors” rather than a single smoking gun.
The senator, who represents Joint Base Langley-Eustis, where the F-22 is flown, said, “We’re going to stay on this until it gets resolved.”
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