BEAUFORT -- Hairline fatigue cracks found on hinges of wing panels on fighter jets at Marine Corps Air Station Beaufort in September forced the Navy to inspect more than 450 F-18 Hornets this month.
During a post-flight inspection in September, cracks in the aluminum outer wing panel hinges were found on a two-seat F/A-18/D flown by one of the air station's all-weather fighter squadrons.
The squadron examined the rest of its jets and found similar cracks at the hinge assembly, said Capt. James Jarvis, air station spokesman.
The air station then notified the Naval Air Depot and Fleet Support Team that there might be a systemic problem with the hinge assembly, Jarvis said.
The hinge is a critical safety part that, if damaged, could "result in ... possible further damage to the aircraft or possible loss of the aircraft," according to a statement from the Navy.
Jarvis said the safety of the aircraft, the Marines flying them and the community below are the air station's highest priorities.
"I can assure you that all of our aircraft are meticulously maintained to ensure that they are 100 percent ready to fly before we clear them to do so," he said.
The Navy issued a bulletin Oct. 23 ordering the inspection of all 636 F-18s in the Naval and Marine Corps inventory.
Inspections of the Navy's 480 jets in active use are nearly complete, said Lt. Clay Doss, Navy spokesman at the Pentagon.
"We were very encouraged by the results and project minimal operational impact," he said, adding that the 112 F-18s currently deployed with Carrier Air Wings and Marine Air Wings have been inspected.
Those inspections resulted in the grounding of 10 F-18s and the placement of flight restrictions on 20 other jets, Doss said.
Half of the Hornets found to have stress cracks are deployed overseas, he said.
"Of the deployed aircraft, two were grounded and eight were flight restricted," he said. "Since then, the two grounded deployed aircraft have been repaired. We will prioritize repairs of deployed aircraft to ensure safe operations and mission requirements are met."
F-18s belonging to Marine Aircraft Group 31 at the air station in Beaufort all have undergone inspections and the handful of planes that required attention were repaired, Jarvis said. Jets belonging to the air station's lone Naval squadron, Navy Strike Fighter Squadron 86, passed inspection.
Each jet is worth about $57 million, according to the Navy. The planes originally were made by McDonnell Douglas, which now is part of Boeing.
Doss said the cause of the problem remains unknown.
"We continue to analyze the data gathered to determine the root cause," he said. "With procedures in place and maintenance techniques under development, we do not expect additional degradation to the Navy's strike-fighter capability resulting from the identified hinge cracks."
Despite flying an aging fleet of fighters -- variants of which became operational as early as 1983 -- preventative maintenance has kept "Class A" mishaps with the F-18 at their lowest rate in nearly a decade, according to the Naval Safety Center.
A Class A mishap is one that causes death, destruction of the aircraft or more than $1 million in damage. Pilots flying F-18s in fiscal year 2008 recorded 1.3 such mishaps per 100,000 flight hours in the Hornet, according to Safety Center data.