The U.S. military has slapped a restriction on any F-35 pilot weighing less than 136 pounds (61.6 kg) as there are worries that person might be injured during low-speed ejections.
A Joint Program Office spokesman said the ruling, in effect since Aug. 27, affects at least one pilot.
The issue was discover during the testing of the seat in August. Testers discovered an increased risk of neck injury when a lightweight pilot is flying at slower speeds. A lightweight person will cause the seat’s center of gravity to shift during an ejection.
Discovered in August? Eric Palmer wrote about this problem five years ago in \”Give me your heavy women.\”
https://ericpalmer.wordpress.com/2009/09/10/raaf-give-me-your-heavy-women/.