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November 17, 2010

Cracked F-35, missing F-22

BF-1 Short takeoff_March_17_10 A busy morning in the defense aviation world. First, it was reported by Aviation Week and confirmed by Lockheed Martin that a crack turned up in one of the major bulkhead pieces on an F-35 ground test plane that was undergoing fatigue testing in Fort Worth.

And the Air Force is looking for an F-22 Raptor in Alaska that failed to return to base Tuesday evening. The Dew Line blog has what little of that story we know right a this moment.

A Lockheed Martin F-22 lost contact with US Air Force air traffic control at 7:40pm (11:40pm EST) yesterday during a routine mission from Joint Base Elmendorf-Richardson in Alaska. A search is underway. As of about 8am EST, the USAF still classified the aircraft and the pilot as overdue.

The USAF has lost two F-22s in accidents since December 20, 2004. Aircraft 014 was lost on that day after maintenance procedures triggered a glitch in the flight control system. Aircraft 008 crashed on March 25, 2009, after Lockheed Martin test pilot David Cooley briefly lost control for 4sec during a 9g, split-S maneuver.

The fatigue crack turned up in the aluminum-alloy bulkhead after just 1,500 hours of testing. The F-35 airframe is designed to last at least 8,000 hours and the intent of the testing was to push it to twice that figure.

How serious a problem the bulkhead crack is remains to be seen. It came in an F-35B model, in which the titanium bulkheads were swapped for aluminum to save weight. If it turns out to be a manufacturing error, that's one set of problems. If it's a design error, that's another.

There are already four F-35B flight test planes flying at Naval Air Station Patuxent River, with another built and ready to follow fairly soon. Based on a previously scheduled walking tour of the Lockheed Martin assembly line this morning, at least five more B-models are in some stages of the final assembly process and another four or five have to fairly far along.

The timing of the discovery isn't good. The Pentagon for weeks has been trying to decide how to proceed with the F-35 program which continues to fall farther behind schedule and over budget, in large part due to problems with the F-35B. It has been widely reported that the Navy made have made another attempt to convince Defense Secretary Gates to drop the Marines short-takeoff-vertical-landing model.

A Defense Acquisition Board will be held Monday to advise and rule on the DoD's plans for continuing with the F-35 program.

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Comments

Lee Gaillard

UNreal. LRIP...just keep churning them out before a prototype is fully wrung out and all design errors corrected. Boeing is having the same problem with the 787, with 20+ aircraft parked around Boeing Field with major parts missing (engines, horizontal stabilizers, etc.) while the company tries to get a handle on all the re-work required because of faulty construction by a major supplier--wing stringers and wing/body join, fuselage skin, horizontal stabilizers.

Haste makes massive waste. What kind of comparative bulkhead new-design testing was done first--with major stresses to the titanium version of the bulkhead then to the aluminum alloy intended replacement? They will also need to check into heat/cooling treatment during and following the forging process for effects on grain size, brittleness, etc.

Then there's the gazillion lines of software that have also been slowing up the process. Where did this 'design-as-you-build' philosophy ever come from. Etc.

'Nuff said.

alloycowboy

Hey Lee,

The design as you go process came from the Wright Brothers, the first aeronatical engineers and pilots. Also, I am not sure if any one ever told you this but engineering is really educated guessing which is why all aircraft go threw a very intensive test program in order to verify that the engineers made the right educted guesses based on initial assumptions and test data.

Tomba

hey alloycowboy, learn how to use spellcheck and you won't sound quite as ignorant.

Josef Prem

As you all know, it's about money. Follow the money.

gar

Anyone who knows aircraft will not make big issue of a crack in the frame while these aircraft are being tested.Half the aircraft flying on their long hours inspection small cracks are found.

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