F-35 Joint Strike Fighter (JSF) 2015 [no mention of the LIGHT/HEAVY switch on the Ejection Seat]
Jan 2016 DOT&E"...
Pilot Escape System• In 2011, the program and Services elected to begin training and flight operations at fielded units with an immature pilot escape system by accepting risks of injury to pilots during ejection. These risks included pilots flying training missions with ejection seats that had not completed full qualification testing and flying overwater without the planned water-activated parachute release system (a system which automatically releases the parachute from the pilot’s harness upon entry into water). Certain risks are greater for lighter weight pilots. Recent testing of the escape system in CY15 showed that the risk of serious injury or death are greater for lighter weight pilots and led to the decision by the Services to restrict pilots weighing less than 136 pounds from flying the F-35.
• Two pilot escape system sled tests occurred in July and August 2015 that resulted in failures of the system to successfully eject a manikin without exceeding neck loads/ stresses on the manikin. These sled tests were needed in order to qualify the new Gen III HMDS for flight release.
- A sled test in July on a 103-pound manikin with a Gen III helmet at 160 knots speed failed for neck injury criteria. The program did not consider this failure to be solely caused by the heavier Gen III helmet, primarily due to similarly poor test results having been observed with Gen II helmet on a 103-pound manikin in tests in 2010.
- The sled test was repeated in August 2015 using a 136-pound manikin with the Gen III helmet at 160 knots. This test also failed for neck injury criteria. Similar sled testing with Gen II helmets in 2010 did not result in exceedance of neck loads for a 136-pound pilot.
• After the latter failure, the program and Services decided to restrict pilots weighing less than 136 pounds from flying any F-35 variant, regardless of helmet type (Gen II or Gen III). Pilots weighing between 136 and 165 pounds are considered at less risk than lighter weight pilots, but at an increased risk (compared to heavier pilots). The level of risk was labeled “serious” risk by the Program Office based on the probability of death being 23 percent and the probability of neck extension (which will result in some level of injury) being 100 percent. Currently, the program and the Services have decided to accept the risk to pilots in this weight range, although the basis for the decision to accept these risks is unknown.
• The testing showed that the ejection seat rotates backwards after ejection. This results in the pilot’s neck becoming extended, as the head moves behind the shoulders in a “chin up” position. When the parachute inflates and begins to extract the pilot from the seat (with great force), a “whiplash” action occurs. The rotation of the seat and resulting extension of the neck are greater for lighter weight pilots.
• The Gen III helmet weighs 5.1 pounds, approximately 6 ounces more than the Gen II helmet. The increased weight is primarily due to the larger/heavier night vision camera optics. The program has a weight reduction project ongoing to determine if approximately 5 ounces can be eliminated in the Gen III helmet by reducing structure and materials without affecting fit or optics. [Removing a day/night visor as appropriate apparently]
• In coordination with the Program Office, the ejection seat contractor funded a proof-of-concept ejection sled test in October to assess the utility of a head support panel (HSP), a fabric mesh behind the pilots head and between the parachute risers, to prevent exceeding neck loads during the ejection sequence for lighter weight pilots. Based on the initial results, the Program Office and Services are considering seat modifications that would include the HSP, but they may take up to a year to verify improvement and install them onto aircraft.
• Additional testing and analysis are also needed to determine the risk of pilots being harmed by the transparency removal system (which shatters the canopy before, and in order for, the seat and pilot to leave the aircraft) during ejections in other than ideal, stable conditions (such as after battle damage or during out-of-control situations).
• The program began delivering F-35 aircraft with a water-activated parachute release system in later deliveries of Lot 6 aircraft in 2015. This system, common in current fighter aircraft, automatically jettisons the parachute when the pilot enters water after ejection and is particularly beneficial if the pilot is incapacitated at this point...."
Source: http://aviationweek.com/site-files/avia ... Report.pdf (361Kb)