The extensible cells are not considered as crashworthy as the non-extensible cells. The first two low-rate initial production lots have extensible fuels cells for sponsons and wings. The military observer noted it would be tragic if the Osprey came down within a survivable crash envelope and then, because of the failure of a fuel cell, burned and killed the Marines onboard. Questions about the true survivability of the extensible fuel cells currently installed in all V-22s were raised by the Marine Corps Judge Advocate General investigation into the April crash. The survivability of the extensible fuel cells is predicated on a cell's ability to expand under a crash condition.
Extensible cells absorb crash energy by deforming.
Non-extensible cells have more tear resistance than extensible cells. Testing of fuel cells included drop tests and gunfire tests. The sponson extensible tanks did not adequately seal after gunfire and leaked 1.5 ounces per minute after drop tests. Those cells were purchased for the first two lots under a waiver. Wing cells passed qualification.