F-35 Program Fixes Wing Problem - Defense News
F-35 Program Fixes Wing Problem
By DAVE MAJUMDAR
Published: 1 Sep 2011 17:40
Technicians with the F-35 Lightning II Joint Strike Fighter (JSF) program have found and corrected a problem with part of the aircraft's wing structure.
As part of the fifth-generation stealth fighter's test program, the jet's structure must be tested to ensure it meets its fatigue life requirement, a standard requirement for all new aircraft.
"During this analysis, a shortfall in the predicted durability life of the Conventional Take Off and Landing (CTOL) and Short Take Off and Vertical Landing (STOVL) wing forward root rib was identified," said JSF program spokesman Joe Dellavedova in an emailed statement.
Lockheed Martin is leading an international program to develop and manufacture the single-engine stealth combat jet for the U.S. Navy, Air Force and Marine Corps and allied military forces.
The root rib is an aluminum part located where the leading edge of the aircraft's wing meets the jet's fuselage. It is required to have a life of
8,000 flight hours, and was slated to be tested to twice that, or
16,000 hours. But during testing, the root rib developed cracks at just
2,800 hours.
Program officials had suspected the problem, Dellavedova said, but proceeded with testing, in coordination with the U.S. Air Force, to gather more data.
"The crack is consistent with analytical predictions, both in terms of location and life," he said.
This sort of problem is not unusual in the development of any new aircraft, said Loren Thompson of the Lexington Institute, Arlington, Va.
In most aircraft programs, dozens of such problems are found and routinely corrected. That includes civilian aircraft such as the Airbus A380 and Boeing 787 airliners, Thompson said.
Dellavedova said the JSF program has developed retrofit plans and a redesigned full-life forward root rib for both variants.
"Resolving durability test article findings is a well-understood process. Durability testing is conducted early in the development of any new aircraft to avoid costly sustainment issues later in the life of the aircraft," he said. "Problems are found and corrected in development rather than fleet service."
In the meantime, the affected F-35s will be inspected regularly until they are retrofitted with the fix, as is always the case with any aircraft.
The new modified forward root rib design will be incorporated into production planes from the beginning of Low Rate Initial Production (LRIP) Lot 5 for both CTOL and STOVL aircraft. A total of 30 CTOL and 34 STOVL LRIP aircraft will need to be modified to fly for their full fatigue life.
This particular modification has been grouped with the existing retrofit requirements to reduce both the cost of the modification and the time that aircraft spend in deeper maintenance, Dellavedova said. It is expected that the forward root rib modification will take about 45 days to complete." ENDS
[Bold by Mac]
There is so much double talk by Dellavedova, yet it seems the F35c is not affected so its root rib must be satisfactory, for now at least.
This begs the question if, as he says, they suspected the problem and accurately predicted the failure and its timeline WHY did they continue building jets and not use the F35C part. The fix for 60 plus jets isn't cheap and maybe the F35c part isn't interchangeable, so much for commonality.
Its been reported elsewhere that he said no new costs will be incurred in repairs. Why? Because the cost of this fix has already been paid for, hidden amongst the recently announced over runs, so no 'new' money is required to fix these 60 plus jets. There's a saving in that?
I think the F35 capabilities are great and much needed but I'm not a fan of how the program to build/test them has been structured and managed.
Mac
