From CNN's Larry Shaughnessy and Jennifer Rizzo
Six F-35 Joint Strike fighter jets have been grounded at Edwards Air Force Base in California after it was discovered that the underseat parachutes for pilots were improperly installed, according to a statement from the Joint Strike Fighter program office.
It's the latest issue for the F-35 program, which has gotten vocal support from Secretary of Defense Leon Panetta, who said the Pentagon committed to the F-35 as the future fighter jet for the military.
The program has been beset by ballooning costs and various technical problems in testing. The latest issue - which is not affecting all F-35s in use by the military - involves parachutes that were inserted backwards under the seats of more than 15 planes that received newer ejection seats, the statement said.
In addition to the six grounded in California, the problem also was discovered in six F-35A and the three F-35B aircraft at Eglin Air Force base in Florida. Those aircraft however were only performing ground tests, which can continue.
Some F-35s still on the assembly line at Lockheed Martin's facility in Fort Worth, Texas, also are affected.
The Martin Baker Aircraft Corporation supplies the aircraft ejection seats. Incorrectly drafted packing procedures led to the error, the statement said.
"This issue would not have prevented the pilot from executing a successful ejection and safe landing in the unlikely event of a pilot ejection, but obviously we want to get it right," said Edwards Air Force Base spokesman Mike Strickler.
The parachutes have to be removed and reinstalled correctly. It will take about 10 days until the first set of repacked parachutes are available.