But to the trained eye of a mechanical engineer, it is a compendium of data revealing not only what has been but what is likely to be for a key air superiority weapon system.
What both are seeing are the remnants of an F-15D fighter aircraft that compiled 6,300 flight hours before suffering mechanical problems too costly to fix. Instead of sending the tired warrior to the Aerospace Maintenance and Regeneration Center at Davis-Monthan Air Force Base, Ariz., Air Force officials decided to subject it to detailed fatigue analysis including a look at parts and components not normally seen during extensive depot maintenance.
The hope is that conclusions drawn from the review will not only show how this specific aircraft fared against the bumps and grinds of fighter duty but also imply how the remainder of the F-15 fleet – with essentially the same structure and components – is holding up.
The first cuts on the fuselage began in April and the data should be completed, analyzed and ready for final review by March of 2010. A second aircraft, an F-15C, will undergo the same process beginning in January with completion expected by September. S&K Technologies is performing the work for the Air Force at its Byron facility.
So far, there have been no surprises on the F-15C.
“We have completed non-destructive inspection on 77 percent of all the parts, and we’ve been very pleased with the results” reported 2nd Lt. Amanda Alpaugh, a structural engineer assigned to the 830th Aircraft Sustainment Group at Robins Air Force Base and the project lead for the analysis. “We haven’t found anything to raise an alarm or suspicion.”
The parts reviews have yielded 211 findings, mainly due to fretting or rubbing. Only five percent of some 24,000 bolt-hole inspections have shown any indication of corrosion or mechanical damage.
“Everything we have looked at so far had been expected,” Alpaugh confirmed. Both the F-15C and the pending F-15D are representative of the entire F-15 fleet in terms of mission stress and operating locations.
“Both had standard rotations through different bases,” the Robins engineer said. “They had tours in high humid places where corrosion is more prevalent and also bases where corrosion is less likely.”
Final conclusions won’t be drawn until work on the F-15C is complete, but Col. Stephen Niemantsverdriet, the F-15 system program manager at Robins, said he was encouraged with the findings so far.
“We have not incorporated any additional inspection points either for the field or the depot,” he said. “However, we are looking to see if there is some consistency with the corrosion and fretting to determine if there is anything we can do, from a design perspective, to help with that.”
Although the F-22, the nation’s newest fighter aircraft, will handle some of the burden in the future, the F-15 will continue to be a mainstay. Some 238 F-15 C and D aircraft will be retained through the year 2022 before the fleet is cut to 176. The 222 newer, more robust F-15Es will remain indefinitely.
Niemantsverdriet said the F-15 still has a long future to go with its distinguished history, a prospect made possible in part by the detailed teardown of the F-15D and C. Although a number of component upgrades are programmed for the fighter, maintaining the structure – the aircraft’s soul – are equally important, the colonel stressed.
“Our challenge is to modernize and sustain the airplane,” he said. “The challenge is to balance avionics upgrades for the aircrews with the sustaining pieces that take so many maintenance man-hours.”
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