Fifteen new Lockheed Martin F-35 fighters, some of which are participating in the flight testing so critical to moving the troubled Joint Strike Fighter program forward, have been grounded owing to improper loading of parachutes in their ejection seats.

The suspension of flight and high-speed ground testing began Jan. 26 and affects aircraft at Edwards AFB, Calif., Eglin AFB, Fla., and Lockheed’s production facility in Fort Worth, Texas, according to Joe Dellavedova at the U.S.-led JSF Joint Program Office. The root cause was “improperly drafted packing procedures,” he adds.

The problematic chutes are not affecting eight test aircraft at NAS Patuxent River, Md., because they carry an earlier version of this seat and the parachutes were properly loaded, he says.

Parachutes for the Martin-Baker US16E-21 and -23 seats were “reversed 180 deg. from design during installation,” Dellavedova says, and replacement seats from British manufacturer Martin-Baker are expected to take 10 days to arrive. “This issue will not prevent the pilot from executing a successful ejection and landing in the unlikely event of a pilot ejection,” Dellavedova says. The problem was uncovered during a routine review, he says, adding that it is premature to discuss any penalties as a result of the mishap.

One industry source notes, however, that an ejection “would have likely caused passenger load factor injury” because pilots would “have hit the ground going backwards.” Because the parachutes were loaded backwards, their steering lines would also have been reversed, affecting a pilot’s ability to guide himself to a landing site.

The affected equipment will have to be shipped back to Martin-Baker’s factory in the U.K. for repair; the repacked chutes will then first be put on the six grounded aircraft at Edwards to return them to flight testing. The six F-35As and three F-35Bs at Eglin AFB, Fla. were already limited to ground operations pending “military flight release” from the Air Force to fly the aircraft unmonitored in the area. So they will be next to receive the newly packed boxes. Eglin flights were held up owing to concerns cited from the Pentagon’s chief tester last fall. Among them was a warning not to fly over water until the -24 seat, the model intended for the operational F-35, is available, owing to concerns of pilot drowning with the older seat versions.

“Aircraft in production at Fort Worth were also affected but their parachutes will be repacked prior to the first acceptance flights,” Dellavedova says.

This mishap comes as Goodrich, the only remaining U.S. ejection seat manufacturer, is in the final throes of attempting to unseat Martin-Baker on the F-35A, which is likely to be purchased by at least 11 countries, with the U.S. Air Force potentially buying as many as 1,763. Without a major program like the F-35, the company’s opportunities to get the Aces 5, the latest in its Aces family of seats, into a new service platform are grim in the near future. The next major opportunity would be the Air Force’s T-38C replacement program, which has yet to formally be kicked off.

Booz Allen Hamilton studied whether the USAF Air Combat Command’s (ACC) use of the Aces 5 seat for its F-35As would save money over the life of the fighter for the service, due to commonality with the Aces 2 seats already in its fleet. “That exhaustive analysis led us to conclude that, while there are potential savings associated with the Goodrich Aces 5 seat, the amount is not sufficiently compelling to warrant the risk and up-front cost of integrating a new ejection seat into the F-35 weapon system at this time,” says Capt. Jennifer Ferrau, an ACC spokeswoman. “ACC and the Air Force strongly support the Joint Program Office’s commitment to pursue efficiencies in order to secure greater value for all JSF stakeholders.”

Lawmakers last year requested information on the study, and the Air Force recently notified staffs of the conclusions. The study or its data will not be released, according to Ferrau, because it contains proprietary information about the pricing of the seats.

The Pentagon was slated to decide in a Joint Executive Steering Board meeting whether it would be open to adding the Goodrich seat to the F-35A in December. But the U.S. decision to slice as many as 179 F-35s from purchasing plans through 2017 prompted officials to move the meeting to March.