Cracks Discovered In Bulkheads During Ground-Based Stress Testing

Cracks discovered last September in bulkheads on the F-35B variant for the U.S. Marine Corps may delay deployment of the STOVL aircraft for another year, according to Pentagon sources.

Bloomberg News reports that the cracks were found in three of six bulkheads during ground-based stress testing of the aircraft, and durability testing was stopped in September. The suspension was just announced by the Pentagon.

Frank Kendall, the Defense Department's undersecretary for acquisition, called the discovery and suspension "significant, but my no means catastrophic." He said that some of the "B" variant's structures will need to be re-designed "based on preliminary analysis."

The deficiency was revealed in an annual report from the head of the Defense Department's weapons testing office Michael Gilmore, who said that during the ground tests, the "cracks continued to grow" until a "bulkhead severed and transferred loads" causing cracking in adjacent bulkheads.

Some bulkheads in the "B" model were made of aluminum rather than titanium found in the "A" and "C" variants as a weight-saving measure. Jennifer Elzea, spokeswoman for the Pentagon test office, said the problem is "significant enough to warrant changes in the design." She said that the cracks were not predicted by past modeling or analysis, but that “we can’t know all the changes that must be made to the structures until the testing is complete, and it is not surprising when discoveries like this occur.”

(F-35B pictured in file photo)

FMI: www.lockhedmartin.com