6/11/2015 - HILL AIR FORCE BASE, Utah -- More than 300 "at-risk" F-16 Fighting Falcons in the active duty, Air National Guard and Air Force Reserve fleets are receiving inspections and subsequent modifications at the Ogden Air Logistics Complex here, in order to ensure structural integrity.
Using innovation and collaboration to better achieve the "Art of the Possible," aircraft structural engineers in the F-16 System Program Office developed a tool which was manufactured by technicians in the 309th Commodities Maintenance Group. The tool allows structural technicians to blend repairs more accurately at precise depths.
The inspections address the Air Force Sustainment Center Way's tenets of safety and quality, and also provide opportunities to save time and cost, according to Mike Spaulding, 573rd Aircraft Maintenance Squadron Deputy Director. In the early stages of the structural work, technicians were blending aluminum bulkheads by hand, using sandpaper. This process proved tedious, was not repeatable and severely slowed the rate of repaired aircraft.
"The aircraft structural engineers from the F-16 SPO designed and 309 CMXG personnel manufactured a fixture that allows the structural technician to blend faster, more accurately and more consistently at precise depths," Spaulding said. "During the tooling design phase, initial test fixtures were actually 'printed' in plastics and metals using three-dimensional additive manufacturing, saving a great deal of time and funds."
Mike Russell, a structures technician with the 573 AMXS who now uses the blending tool, said, "It's actually a good system, very user friendly and the Process Order is easy to understand. I see it working really well into the future."
The use of this blending tool, coupled with other associated process improvements, has prevented time- and labor-intensive bulkhead changes and resulted in a 10-day reduction in the time an aircraft remains on the depot repair line, thus increasing aircraft availability for the warfighter.
"In cost terms, this amount of reduction easily reduces the cost of the overall repairs by tens of thousands of dollars to our major commands," Spaulding said. "This team-centered experience in applying AFSC Way principles reinforced the importance of empowering our workforce to identify constraints and solve problems at the lowest level."
The 573 AMXS began performing the three major structural inspections -- nicknamed the "3 Amigos" -- in May 2013. Guided by three Time Compliance Technical Orders, the inspections are designed to strengthen the aircraft where the wings attach to the fuselage.
"Since the beginning of the inspection, Ogden ALC technicians implemented the first inspection seamlessly, while the other two created some production challenges," Spaulding said.
The first inspection replaces the wing bolts, while the second inspection focuses on the condition of the bolt holes where the wing attaches to the fuselage.
"If they found stress cracks, our technicians installed a doubler plate to beef-up the existing structure," Spaulding said. "These doublers, locally manufactured by the 309 CMXG, are permanently bonded then bolted into place."
However, a Non-Destructive Inspection revealed air pockets and voids behind the doublers, forcing the need to remove and replace them. The doubler and installation process was redesigned by enterprise partners including the Complex's NDI technicians, F-16 Systems Program Office aircraft structural engineers and 309 AMXG process engineers. The new process has eliminated 90 hours of costly rework.
The third inspection -- TCTO 2675 -- looks for cracking in four bulkheads on each side of the F-16. The smaller cracks were milled out, while larger cracks necessitated removing and replacing the bad bulkhead.
"For TCTO 2675, we worked with the Air Force Research Laboratory at Wright-Patterson AFB, Ohio, and they hired UniWest Eddy Current Equipment to design a custom NDI probe that has proven to be extremely successful in helping us trust the reading and increase the inspection intervals for the field," said Matt Fowers, F-16 Structures mechanical engineer. "It allows us to assume they are detecting smaller cracks than they originally were with the old off-the-shelf ribbon probe."
Fowers explained the custom milling tool can analyze the stress experienced by using computer models, based on the profile that the mill bit creates. Inspectors can then be confident with the re-inspection intervals which are important for the health of the pre-block F-16 fleet.
"The tool has been critical to providing the end goal of regaining structural integrity of the aircraft so we can get these aircraft to the end of their designed service life. It allows us to make the process repeatable, predictable and reliable," Fowers said.
The added tools and partnership cooperation have saved about 10 days in production time for each aircraft. A previous aircraft that went through the old process took nearly a year to complete -- and it is estimated that under the current system, the work would have only taken a couple months.
"By implementing an enterprise-wide approach to process development and improvement, we improved safety, quality, speed and cost effectiveness, and can now better monitor '3 Amigo' inspections and repairs throughout the production process along with our SPO partners," Spaulding said. "Looking to the future, the 573 AMXS has already begun to incorporate lessons learned from this effort to other production processes, seeking world-class, cost-effective readiness for our Air Force."
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