The Air Force is unsure exactly how long detailed inspections of its F-16Ds will take after preliminary inspections revealed cracking that resulted in the grounding of more than half its fleet.
“Some airframes have no damage whatsoever and other airframes have varying levels of damage,” Air Force spokesman Capt. A.J. Schrag told Defense Daily Friday. “As a consequence of some of this variability, they’re really struggling to be able to nail down an actual timeline.”
The Air Force said Aug. 19 it removed 82 of its 157 two-seat F-16D fighter jets from flight status due to the discovery of canopy sill longeron cracks found between the front and rear pilot seats (Defense Daily, Aug. 20). Longerons are typically made of aluminum alloy, run the length of the jet and are a type of support structure between the frame and the skin of the aircraft. Longerons help prevent tension and compression from bending the fuselage. A canopy sill is the support structure surrounding contact points between the frame and canopy.
Schrag said while preliminary inspections are complete, further, more detailed inspections are ongoing and once the Air Force identifies an issue with a specific airframe, then it will dive deeper and try to identify the extent of the damage. An Air Combat Command (ACC) spokesman said Aug. 20 that the two ACC F-16Ds affected by the longeron cracking were expected to return to flight within four to six months, though he cautioned this does not necessarily mean the rest of the fleet would be out this long.
The F-16D fleet, the two-seat variant of the F-16 primarily used for training, is on average 24 years old with more than 5,500 hours of flight time. For the F-16C/D variant, initial operational capability (IOC) was declared for Block 25-32 in 1981, Block 40-42 in 1989 and Block 50-52 in 1994. There are a total of 969 F-16s of all variants in the Air Force. Lockheed Martin [LMT], which develops the F-16, deferred comment to the Air Force.