By Andrea Shalal
WASHINGTON, Aug 21 (Reuters) - The continued grounding of 82 Lockheed Martin Corp F-16 fighter jets due to cracks in structures between the front and rear pilot seats reveals strains facing the aging fleet of Cold War-era fighter jets and underscores the U.S. Air Force's need for new equipment, analysts said.
The Air Force this week said it had ordered immediate inspections of all 157 of its F-16 two-seat D-model jets after discovering cracks during inspections conducted after flights, but later allowed 75 of the jets to resume flying. The D-model jets are 24 years old on average, with more than 5,500 flight hours.
"The Cold War fighter fleet is aging rapidly. When you fly at supersonic speeds and get multiples of normal gravity ... it's inevitable that the equipment is going to wear out," said Loren Thompson, chief operating officer of the Virginia-based Lexington Institute.
Thompson, who also works as a consultant for Lockheed, said the grounding underscored the need for the Air Force to start replacing its older fighters with the newer F-35, also being built by Lockheed.
Officials are developing repair options for the grounded jets, which were found to have cracks in the longerons, or stiffeners, used around the canopy of the jets.
The Air Force has a total of 969 F-16s in its fleet, but only the D-model jets, which are mainly used for training, were affected by the cracking, according to an Air Force statement.
It said the Air Force was working with its F-16D operational units to reduce the impact of the grounding on operations, training and readiness.
Richard Aboulafia, defense analyst with the Virginia-based Teal Group, said the grounding followed a similar incident in 2007 involving the Air Force's F-15 fighter planes, which were built by Boeing Co.
He said such incidents were likely to increase in coming years, given the relatively slow pace at which the U.S. military is buying the F-35 fighter jets that will replace the F-16s.
"It's going to get worse," Aboulafia said, noting that ongoing budget pressures meant U.S. officials were now having to choose between upgrading existing F-16s and making repairs to keep the planes flying. The Air Force canceled some planned upgrades in its 2015 budget proposal, citing budget pressure.
"It's an ongoing slow-motion crisis," he said. "We stopped building fighter jets in large numbers, but we didn't stop using them in large numbers."
The Air Force plans to buy a total of 1,763 F-35s, but its orders have been scaled back sharply for budget reasons, and to address technical challenges, in recent years.
Lockheed said it was working actively with the Air Force and international F-16 customers to address the inspection findings.
The company announced on Wednesday that the newest F-16 configuration, the F-16V, had successfully integrated a new active electronically scanned array (AESA) radar, completing a critical milestone for the program on schedule.
Taiwan is the launch customer for the new F-16V model.
(Reporting by Andrea Shalal; Editing by Leslie Adler)