An F-15C Eagle from Langley Air Force Base, Va., flies over Washington during an early morning combat air patrol mission in support of Operation Noble Eagle. (U.S. Air Force photo by Staff Sgt. Greg L. Davis)
by Tech. Sgt. Russell Wicke
Air Combat Command Public Affairs
12/10/2007 - LANGLEY AIR FORCE BASE, Va. (AFPN) -- Air Force maintainers continue to perform methodical and time-intensive inspections on all F-15 Eagle A, B, C and D model aircraft which are revealing more cracks in the aircraft longerons.
The discovery of more structural damage in the F-15s prompted the Dec. 3 stand-down order from Air Combat Command Commander Gen. John Corley.
The decision follows additional information received from the ongoing investigation of the Nov. 2 F-15C mishap, which resulted in the loss of that aircraft. The Accident Investigation Board found defects which indicate potential structural damage in the rest of the fleet.
Maintainers at Langley have found no cracks or evidence of fatigue in F-15 longerons so far; however, throughout the Air Force, maintainers have found cracks in the upper longerons of eight F-15s (as of Dec. 10). Four of these aircraft are assigned to the Air National Guard's 173rd Fighter Wing, Kingsley Field, Ore.; two are assigned to the 18th Wing, Kadena Air Base, Japan; another is assigned to the 325th Fighter Wing, Tyndall AFB, Fla.; and one assigned to the ANG 131st Fighter Wing, St. Louis, Mo.
Every aircraft will undergo all previously published time compliance technical order inspections. However, unlike in recent weeks, the cleared aircraft will not immediately return to flight. Technical experts at Warner Robins Air Logistics Center, Ga., are developing new inspection techniques based on findings in parts of the mishap aircraft. These inspections will be performed as soon as the new TCTO is available for the affected F-15s.
As part of the previous TCTO, maintenance crews around the Air Force are stripping paint and performing non-destructive inspections in the F-15's upper longeron just aft of the canopies.
Maintainers are working around the clock to conduct these inspections, said Capt. Timothy Blasiman, the 71st Aircraft Maintenance Unit officer in charge.
Each of the 20 F-15s assigned to Langley require a minimum inspection time of 12.5 hours. Some F-15 models elsewhere require inspections that take more than 20 hours. The B and D models are more time consuming, said Captain Blasiman, because they have two seats. The rear seat requires removal to access the upper longerons.
Inspections are more than just a visual check, said Staff Sgt. Aaron Gammill. After the paint is stripped and bare metal is exposed, Airmen from the non-destructive inspection shop apply chemicals that reveal cracks under a black light. Other inspections in hard-to-see areas are done with a borescope - a tool that uses a tiny camera and fits in tight areas.
Inspections must be meticulous because the nature of the problem could lead to loss of life or aircraft, said Bo Floyd, the Air Force F-15 Engineer Technical Services lead.
Air Force officials are not willing to take risks in this matter, Mr. Floyd said.
"Our mission is to generate sorties and maintain a combat-effective airplane here," said Captain Blasiman.
Inspection requirements are precise and demanding, said Ralph Farley, the ACC Engineering Technical Service representative.
"Pieces of the crashed jet have been (retrieved) and sent to the Air Force research lab ... to see what may have caused the aircraft to disintegrate," he said. "That information is going down to (our engineers) where they will determine how to inspect, what will be inspected and the form in which it's done."
Airmen from ACC and engineers from Warner Robins are doing everything to ensure the Air Force's F-15 fleet returns to flight safely, Mr. Farley said.
