Luke returns F-16Ds to flight after longeron repair Published Dec. 24, 2014 By Staff Sgt. Luther Mitchell Jr. 56th Fighter Wing Public Affairs LUKE AIR FORCE BASE, Ariz. (AFNS) -- Air Force officials removed 82 two-seat F-16D Fighting Falcons from flight earlier this summer after discovering cracks along the canopy sill longeron between the front and rear pilot seats. The longeron is a major structural component that carries significant loads during dynamic flight operations of the F-16. Of the 82 aircraft, 32 belong to the 56th Fighter Wing at Luke Air Force Base, Arizona. Aircraft maintainers at Luke AFB, in conjunction with 309th Aircraft Maintenance Group depot field teams from Hill AFB, Utah, have been working on getting those F-16s back into the air since mid-October and are nearing completion of repairs on the 32 F-16D aircraft that belong to Luke. "Lockheed and Air Force engineers at the depot designed a repair and now we are out to fix the whole fleet of F-16Ds," said Master Sgt. Thomas Hartley, the 309th AMXG section chief. At the end of July, technicians from the 56th Maintenance Group identified cracks in the left longerons of four F-16D aircraft. This discovery led to the release of an Air Force-wide time compliance technical order in early August directing more in-depth inspections of all F-16D aircraft. Individual F-16 units across the Air Force conducted these inspections on a total of 157 F-16D aircraft identifying 82 with cracks. After engineers from Hill AFB and Lockheed Martin analyzed the F-16D structural issues associated with the cracks and developed repair procedures, three depot field teams were dispatched to start repairs on Luke's jets. Maintainers began the repair by removing the fasteners to the canopy sill longeron and inspecting them for cracks. If cracks were detected, maintainers submitted an engineer's disposition and reamed the cracked holes larger to completely remove the cracks. They then installed the longeron fasteners and a steel "beef-up" strap over them to help strengthen the cracked area. Lastly, they installed high-strength fasteners, applied an aerodynamic smoothing compound and painted the skin. The eight-man field depot team has been working 12-hour shifts, six days a week to get Luke's F-16Ds ready to fly. They've even seen improvements in their repair times. "The grounding of the F-16D has had a big effect on the pilot training mission," Hartley said. "This is a high-priority job for us. We were able to take a six-day repair and trim it down to three and a half over the last month. We feel great about what we have been able to do." In November, the first F-16D was returned to operational status at Luke. "We have accomplished repairs on 30 of the 32 aircraft that needed repairs," said Senior Master Sgt. Ronald Tann, the 56th Aircraft Maintenance Squadron assistant superintendent. "It's great for Luke and the Air Force to get these aircraft back in the air. They are vital to the success of our mission to train and develop combat-ready pilots." The remaining two aircraft are currently awaiting engineering assessments with repair completion expected by early January. "The outstanding teamwork and efforts of Luke maintainers and the depot field teams accelerated repair actions on the F-16Ds and shaved a full month off of the original estimated time to repair all 32 aircraft," said Col. Rick Ainsworth, the 56th MXG commander. "I'm very proud of the professionalism, skill and teamwork of our maintainers and the depot field team, who repaired these aircraft and got them back in the air. Professionals from across the Air Force F-16 enterprise helped us take one of the most challenging F-16 fleet issues we've seen in years and turn it into a success story."