F-35 update - Curt Lewis

F-35 Ejection Seat Fix For Lightweight Pilots Delayed

Martin-Baker

The integration of F-35 ejection seat modifications that will allow lightweight pilots to safely fly the aircraft is taking longer than planned, as the government-industry team works to incorporate new data into the fighter's fleet management system.

The retrofitting of more than 200 early versions of the F-35 already out in the fleet with the new configuration of the Martin-Baker ejection seat will not be completed until about summer 2019, according to F-35 Joint Program Office (JPO) spokesman Joe DellaVedova.

The U.S. Air Force in May lifted a weight restriction banning pilots weighing less than 136 lb. from flying the F-35, after accepting planned modifications to the escape system aimed at allowing lightweight pilots to fly the new fighter without excessive risk. At the time, Brig. Gen. Scott Pleus, then chief of the Air Force's F-35 integration office, estimated the service's full fleet of more than 100 F-35As would be retrofitted with the fixes by this December or January.

When the government-industry team first started doing installation work in April, they discovered the process for swapping out the seats was taking longer than planned-weeks instead of days, DellaVedova said. This was due to incomplete data packages that delayed inputting seat part numbers into the F-35's Autonomic Logistics and Information System (ALIS), the aircraft's computerized internal logistics system designed to electronically track each part of each plane.

The JPO is implementing a solution to resolve the issues, and will ramp up to producing about 14 seat modifications per month starting in December, DellaVedova said.

"All F-35 ejection seats meet requirements and provide safe escape envelopes for pilots," DellaVedova said, stressing that there are no pilot impacts or operational issues associated with the ejection seat modifications. "There is no mission impact to the current operational fleet-pilots can safely fly with any F-35 seat."

All new F-35s coming off the production line in Lot 10 and beyond will have the latest version of the seat, complete with the lightweight modification, he said.

Lockheed Martin has already delivered well more than 100 F-35As to the Air Force to date, service spokesman Capt. Mark Graff said. Four F-35s at Luke AFB, Arizona, the Air Force's main F-35 training base, already have been updated with the new configuration of the ejection seat.

Graff also stressed that the delay has not yet caused any operational impact, or affected pilot training. None of the U.S. services currently have F-35 pilots who weigh less than 136 lb.

"While the integration of the ejection seat modifications is taking longer than planned, we are working to improve the installation process to incorporate the new kit data into the overall ALIS system," a Lockheed spokesperson said. "The F-35 ejection seat's advanced components integrate with our ALIS fleet management system to allow maintainers to track the seat's parts and performance throughout its life cycle. This enables a data-driven sustainment capability to proactively implement scheduled component maintenance and track required repairs and time-based parts replacement."

The danger for lightweight pilots was discovered in the summer of 2015, and led the U.S. military services to bar pilots under 136 lb. from flying the F-35. The issue was a complex problem with the design of the F-35's escape system that posed a significant risk of neck damage or death during ejection to pilots in the lowest weight range.

An ejection is a dangerous event even in ideal circumstances, with opportunities for injury at almost every stage. Once the pilot signals the plane to eject, a set of small explosives breach the windscreen canopy so the pilot can exit the aircraft. The pilot and seat are then launched upward via a rail system in a violent jolt that can cause back and neck injuries if the pilot is not in the correct position, with his or her head directly centered on the spine. The potential for injury is exacerbated by the weight of the F-35's heavy helmet, which forces the pilot's head down.

Once the pilot and seat reach the top of the rails, a rocket under the seat is ignited to lift the pilot-and-seat package free of the plane. At this point, the seat can begin pitching back and forth, a motion much like that of a rocking chair. The pilot's physical build determines the direction and degree of the pitching motion; a tall, heavy person tends to pitch forward, while a short, light person tends to pitch back, sometimes even rotating a full 180 deg.

If a pilot's position is too far back when the main recovery parachute deploys, serious and potentially fatal neck injuries can occur.

Martin-Baker and industry partners last year came up with a three-part fix to protect a lightweight pilot's head and neck in the event of an ejection: a lighter helmet to help ease strain on the neck during the first phase of an ejection; a lightweight switch on the seat to delay deployment of the main parachute; and a fabric panel sewn between the parachute risers that will protect the pilot's head from moving backward during the parachute opening, called a "head support panel," or HSP.

"These modifications combined allowed us to open up the pipeline across the entire planned pilot weight demographic of 102 to 245 lb.," Pleus said in May.

The team is trying to fix the problem as rapidly as possibly, said Richard Johnson, a Martin-Baker spokesman, stressing that "it's not a technical issue-this is an administrative issue."