Bomber returned to inventory after lengthy, critical structure repair Published June 12, 2009 By Howdy Stout Tinker Public Affairs TINKER AIR FORCE BASE, Okla. -- One of the country's high-demand B-1s, commonly known as the BackBONE of Freedom at Tinker, recently had a major operation. Ellsworth Air Force Base, S.D., aircraft 86-0125, nicknamed Swift Justice -- returned to the fight last month thanks to help from Tinker engineers who helped replace the aircraft's main longeron in only the second repair of this type ever undertaken on a B-1. Composed of titanium and boron, the longeron serves as the aircraft's "backbone." "It's the main stiffener of the aircraft," explained Brian Koehl, engineer with the 554th Aircraft Sustainment Squadron. "Think of it as your vertebrae, and that's what it is." A broken weld on a duct line carrying 500-degree bleed air from the engines flooded the area housing the longeron, debonding epoxy holding the composite boron stiffener from the titanium of the longeron. Although still airworthy, the damage effectively grounded the aircraft from combat operations. Mr. Koehl and others flew to Ellsworth, inspected the damage and determined that the aircraft could make the trip to Boeing's C-17 repair facility at Long Beach, Calif., as the Oklahoma City Air Logistics Center didn't have space or capacity to handle the year-long repair in addition to its ongoing depot-level maintenance of other B-1s. But Tinker's expertise was essential as members of the 554th and 565th ACSS, along with local Boeing engineers, went to work on solving the problem of replacing what is a custom-made part for the aircraft. Another B-1 in 1996 had its main longeron replaced, but Mr. Koehl said the documentation of how the repair was accomplished was scanty and provided little guide for this particular repair. After arrival at Long Beach, the first step was removing the 47-foot-long longeron. That involved relieving stress on the structural member, jacking the aircraft at several points and using an aft fuselage cradle found in storage at Tinker. "It was difficult to get everything just right," Mr. Koehl said. "It took us about two weeks total to remove the longeron." Mr. Koehl and others also retrieved the bonding jig from the 309th Aerospace Maintenance and Regeneration Group at Davis-Monthan Air Force Base, Ariz. The jigs, which would hold the titanium longeron in place while the boron stiffener cured, had been left unused at the desert scrap yard since 1997. The refurbished jig, along with the longeron in a newly-made transportation fixture, was sent to Boeing's Seattle facility for bonding with the boron. The boron, a composite material, was applied to the longeron in 330 layers totaling four inches deep and four inches wide. Every 10th layer was a cross ply, requiring cuts by ultra-sonic knives. "That boron is very strong," Mr. Koehl said. "We went through a thousand blades." The boron also has a limited "workable" life of 15 days before it loses its integrity. Crews worked around the clock for 11 days to apply the boron. Then it was cured under pressure for 24 hours in the only autoclave large enough to hold the backbone. The finished product returned to Long Beach for installation in the B-1. In addition, engineers found the heat from the broken bleed air duct had damaged the panels directly over the intermediate weapons bay. Replacements came from B-1s stored at Davis-Monthan and used as a source for spare parts. Mr. Koehl spent eight weeks at Long Beach overseeing the repairs, which involved replacing some 900 bolts and 500 fasteners to hold the longeron and numerous brackets in place. "And that's not counting all the panels," he said. Once the repaired longeron was installed, engineers inspected the work and gave it the thumbs up. "The repair looked like they did a good job," said Boeing engineer Paul Blasi. "From my perspective, it looked as good as newly fabricated." Barbara Alexander, production management specialist for the 553rd, said the project involved vast amounts of cooperation between Boeing, the Air Force and engineers at Tinker. But for all the challenges, the repair went relatively smoothly and ahead of schedule. Daniel Ivester and Gary Valdez of the 76th MXW at Tinker joined Mr. Koehl in Long Beach to assist with the aircraft's auxiliary power units and engines. With these functioning, the remaining 100-plus pre-flight ground checks were completed. Swift Justice was ready to fly. The last hurdle, however, involved gaining departure clearance for the aircraft from Long Beach itself. An earthquake the day before the scheduled departure date had city officials nervous that the noise and vibration might further damage the terminal building already weakened by the 4.7-magnitude quake. Officials eventually gave the go-ahead and crowds gathered to watch Swift Justice make the flight back to Ellsworth. "I arrived in Long Beach in time to do some minor sightseeing," said Lt. Col. Jeff DiCicco of Air Combat Command headquarters in Langley, Va. "Imagine my surprise as I was climbing up to the forward deck of the Queen Mary to hear a low rumble spreading across the landscape. I immediately raced forward to get a better view of whatever it was and, low and behold, a single B-1 was taking off from Long Beach...Absolutely nothing beats the afterburner roar of a B-1 waking up the coast of California." "They made it back to Ellsworth with no defects," Mr. Koehl said. After minor scheduled maintenance, the aircraft will be released back into service for combat operations no worse for wear after the 15-month repair work. "This aircraft is one of the better flyers out there," Mr. Koehl said. Unlike the repair in 1996, this effort is well documented for future use. "Hopefully we don't have any ducts rupturing in the future," Mr. Koehl said. "But if it does happen again, we'll be prepared for it."