Some USAF C-130s Grounded Still

Upper wing barrel nuts on half of USAF's cargo C-130s have kept that veritable trooper grounded. The C-130 has been the backbone of the tactical airlift command for the Air Force since 1956 when the first C-130s went operational.  The C-130 is built by Lockheed Martin.

Officials in the 330th Aircraft Sustainment Group at Robins Air Force Base have issued a worldwide inspection order on March 4th after finding five cracked nuts in a C-130H undergoing depot maintenance on the base.  That order effectively grounded the fleet - including the newest C-130s, the "J" models, until they were inspected.  The nuts and other related bolts - 26 per aircraft - anchor a rainbow-shaped fitting that holds the wings to the center wing box on the aircraft's fuselage.

There are more than 2,000 C-130s in 70 different variants and five basic models have been produced for the United States and other foreign countries.

With 90% of about 600 USAF aircraft inspected, 266 were found to have three or more suspected barrel nuts.  Terrence May, director for the 330th Sustainment Group provided the following information to the Macon Telegraph, "If they had two or less, it was considered a safe condition and they were returned to service."

The suspected nuts, traced to a single vendor, are readily identiffable, May said.  "You can't tell if they are cracked by eyeballing them.  The cracked area would be on the underside of the nut in the threaded area."

They had already shipped out replacement bolts to aircraft operating in Iraq and Afghanistan.  

May also added, "The lab analysis may show a manufacturing defect or it may indicate that a particular type of high-strength steel is not suitable for this application."

The Robins engineers are not too much concerned about the actual flight loads - but the stress of landing tends to be the main concern.  And operating on unimproved runways is also a concern.  

Director May offered praise for his engineering and technical staff.  Specifically for their ingenuity and the staffing of a nonstop, telephone hot line for units around the world.  He was hopeful that they would be able to discontinue the hot line by the middle of next week.

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Ref. Macon Telegraph, March 13, 2009 - Robins Air Force Base, GA. (http://www.military.com/news/article/half-of-af-c130s-remain-grounded.html?ESRC=dod.nl )