The Air Force has set F-35A pilot weight restrictions after ejection seat testing revealed “unacceptable risk of neck injury” in some ejection scenarios for pilots weighing less than 136 pounds, according to an Air Force press release. Recent testing at low-speed conditions in the flight envelope identified a risk of neck injury during parachute deployment and opening for lighter-weight pilots. The DOD requirement is for the seat to be certified for any pilot weighing between 103 and 245 pounds.
While Martin-Baker and Lockheed Martin continue to work on a solution to meet the requirements for the e-seat, Air Force leaders decided on the interim solution of restricting any pilots below 136 pounds from flying the aircraft. The heavier next-generation Helmet Mounted Display System (HMDS) helmets that are a key part of the aircraft’s superior situational awareness for the pilot are reportedly a factor in the ejection issues, with lighter pilots possibly lacking the neck strength to handle the forces imposed by the parachute deployment and opening shock. The Air Force says only one pilot has been affected by the ban.
The Air Force says the probability of an ejection in this portion of the flight envelope is very low, in the region of one in 100,000 flight hours, but the “risk of a critical injury in that circumstance is currently higher” than in older fighter ejection seats.
“We expect the manufacturer to find and implement a solution,” said Secretary of the Air Force Deborah Lee James. “We must ensure the ejection seat is tested to meet our specifications and weight requirements. We are going to ensure this gets done right.”
Capt. Brad Matherne of the 422nd Test and Evaluation Squadron views the flightline inside an F-35A Lightning II before a training mission April 4, 2013, at Nellis Air Force Base, Nevada. The F-35A Helmet Mounted Display Systems display airspeed, heading, altitude, targeting information and warnings on the helmet’s visor, as well as infrared imagery from six cameras mounted around the aircraft and night vision through the use of an integrated camera, but with a cost in increased weight and bulk over conventional helmets. U.S. Air Force photo by Senior Airman Brett Clashman
While pilots below 136 pounds are restricted from flying the F-35A, pilots between 136 and 165 pounds are also at increased risk from the Martin-Baker US16E ejection seats, according to the release. The US16E seats are common to all F-35 variants, but there have so far been no similar weight restrictions set by the Navy or Marine Corps for their pilots. The Air Force says the probability of an ejection in this portion of the flight envelope is very low, in the region of one in 100,000 flight hours, but the “risk of a critical injury in that circumstance is currently higher” than in older fighter ejection seats. Based on the low probability of such an ejection scenario, however, and the fact that there have been similar levels of risk in previous ejection seats, the Air Force decided to allow pilots between 136 and 165 pounds to continue flying the aircraft while work continues on fixing the problem. Pilots with the physique of Jek Porkins are presumably safe to eject in all flight scenarios.
“While the F-35 is a program in development, safety is always at the forefront and a built in expectation,” said Maj. Gen. Jeff Harrigian, the director of the F-35 Integration Office. “As issues are discovered, the Joint Program Office immediately works with the manufacturer to take action and get fixes in place.”
The Air Force admitted concurrent testing and production to speed introduction of the F-35 mean the aircraft are “still in a development phase” and that as problems are found fixes will be made.
“The airmen who maintain, launch, and fly these jets every day are doing tremendous work,” said Air Force Chief of Staff Gen. Mark A. Welsh III. “Because of their hard work and long days in the training classrooms, briefing rooms, the back shops and on the flightline, we expect to achieve initial operational capability in 2016. However, we won’t cut corners. The weight restriction is an interim fix and the expectation is for industry to reach a solution on the ejection seat as quickly as possible.”