Routine Checks Reveal Stress Cracks On 15 Aircraft

More aging US military aircraft are under investigation for possible airframe fatigue issues. Inspections have been ordered for all US Navy and Marine Corps F/A-18 Hornets after finding stress cracks in aileron hinges on at least 15 planes.

Thursday's inspection bulletin affects F/A-18 A through D models, with some 636 aircraft to be checked within their next 15 flight hours. Of those older "legacy" aircraft, 112 are actively deployed, the Navy Times reported.

"Those aircraft that do not pass inspection criteria will be grounded or flight restricted until failed material is replaced," said Navy spokesman Lt. Clay Doss, adding that so far none had been grounded.

Earlier this month, during a routine post-flight maintenance inspection of an F/A-18, a crack in an aileron hinge was discovered, which led to inspections of Hornets from various squadrons. When similar cracks were found on 14 other planes, a fleetwide inspection bulletin was issued.

Doss said priority will be given to the 112 deployed aircraft to reduce the impact on current missions. Inspections, which will involve "nondestructive testing," are expected to be completed within a two-week time frame.

Options include replacing the entire outer-wing panel or replacing the hinge itself, Doss said. Replacing just the hinge would require taking the aircraft to a repair depot, and if necessary, the process of swapping out an outer-wing panel takes about four days.

Boeing spokesman Philip Carder said, "Boeing will work closely with the Navy throughout the inspection process to determine the scope of any cracking on the F/A-18 A-D Hornet fleet and determine the best course of action for repair. A more complete assessment of the extent of this issue will be made after all inspections are accomplished."

News of the Hornet inspections come less than a month after the US Air Force ordered immediate inspections for 127 A-10 Thunderbolt II ground-support aircraft, after fatigue cracking was discovered on the wings of some planes. Last year, the Air Force grounded older F-15 Eagle fighters, following the in-flight break-up of a C-model fighter during a Missouri Air National Guard training operation.

The F/A-18s under scrutiny reportedly have accumulated between 5,000 and 7,500 flight hours, which is still well within the Hornet's twice-extended 10,000 hour maximum life span. But concerns are arising about a gap between the expected retirement of the older McDonnell-Douglas (now Boeing) F/A-18s and arrival of their replacement, the Lockheed-Martin F-35C.   

The deficit, which is forecast from 2015 to 2025, is likely to be at its maximum in 2017, when the overall count is predicted to be down by 69 aircraft.

FMI: www.navy.mil, www.usmc.mil, www.boeing.com