The Air Force’s Air Mobility Command has ordered the temporary removal of over 100 C-130 Hercules military transport aircraft from service for inspections following discoveries of “atypical cracks” during maintenance.

AMC Commander Gen. Maryanne Miller directed an immediate time compliance technical order (TCTO) inspection to identify and correct any cracks along the lower center wing joint – also known as the “rainbow fitting” that provides structural support within the wings – of 123 C-130H and C-130J-model aircraft. The service maintains 450 total aircraft in the fleet, the command said in an Aug. 7 release.

A U.S. Air Force Lockheed Martin C-130J Hercules aircraft. Photo: U.S. Air Force.

Thirty-six C-130J variants and 95 C-130H variants were affected, said AMC spokeswoman Nicole Ferrara in an Aug. 8 email to Defense Daily. Affected aircraft were based at both U.S. and overseas locations.

The complete list of affected bases includes Little Rock AFB, Arkansas; Dyess AFB, Texas; Yokota Air Base, Japan; Ramstein AB, Germany; Hurlburt Field, Florida; Cannon AFB, New Mexico; Keesler AFB, Louisiana; Maxwell AFB, Alabama; Minneapolis-St. Paul Reserve Station, Minnesota; Patrick AFB, Florida; Peterson AFB, Colorado; and Youngstown Air Reserve Station, Ohio. Impacted Air National Guard C-130s were also found at Carswell, Texas; Channel Islands, California; Charleston, South Carolina; Cheyenne, Wyoming; Harrisburg, Pennsylvania; Little Rock Air National Guard in Louisville, Kentucky; Minneapolis-St. Paul, Minnesota; Peoria, Illinois; Quonset, Rhode Island; Savannah, Georgia; Schenectady, New York; St. Joseph, Missouri and Wilmington, Delaware.

“In accordance with the TCTO, in-depth visual and modified non-destructive inspections of the wing box will be conducted on affected … aircraft that have not received the extended service life center wing box and have greater than 15,000 equivalent flight hours,” the release said. That means no aircraft produced after 2008, when the production line started installing a redesigned Enhanced Service Life (ESL) center wing box on new aircraft, are affected by the TCTO, Ferrara said.

Any impacted aircraft will require a depot-level replacement of the rainbow fitting, while unaffected aircraft will be immediately returned to service.

The temporary removal of the affected C-130s are not expected to impact ongoing support to overseas contingency operations, per the command.

“The C-130 Program Office has contacted other U.S. government operators as well as partner nations to recommend they assess the risk to their fleets,” Ferrara said. No Special Operations Command AC-130Js were affected, as these aircraft have a SOF Extended Service Life Wing Box, she added.

This latest grounding follows the springtime removal of 60 C-130H aircraft from service to examine and replace aging engine propeller blades.

Air Force officials told the House Armed Services Seapower and Projection Forces Subcommittee last September that the service needs to “do more and go faster” to modernize the C-130 fleet.

Lt. Gen. Jerry Harris, then-Air Force deputy chief of staff for strategic plans and requirements, told the subcommittee that declining budgets, uncertain scheduling and strategic realignment for changing threats have all impacted recapitalization efforts for the aircraft, which provide for missions including tactical airlift, Antarctic resupply, aeromedical evacuation, search-and-rescue, and special operations support. Harris became the service’s deputy chief of staff for plans and programs in October 2018.