The U.S. Air Force's grounding of more than half its fleet of F-16D fighter jets highlights the need for ongoing structural upgrades of the aging aircraft.
The Air Force on Tuesday announced it had grounded 82 of the two-seater versions of the Fighting Falcon made by Lockheed Martin Corp. after finding cracks between the front and rear pilot seats. The service has an overall F-16 fleet of almost 970 aircraft, including 157 F-16D models, which entered production in the 1980s and are mostly used for training.
"As aircraft accumulate flight hours, cracks develop due to fatigue from sustained operations," Lt. Col. Steve Grotjohn, deputy chief of the program office's Weapon System Division, said in a statement. "Fortunately, we have a robust maintenance, inspection and structural integrity program to discover and repair deficiencies as they occur."
The problem was discovered during a routine post-flight inspection in a section called the canopy longeron sill, a strip of material that affixes to the fuselage. A fleet-wide review of the aircraft was completed Aug. 18.
The Air Force is working with Lockheed Martin to develop a temporary fix that would allow "aircraft with cracks to resume operations for a limited number of flight hours while analysis continues on a permanent fix," according to the statement.
It wasn't immediately clear whether the issue could be addressed as part of an ongoing effort to upgrade the venerable fourth-generation fighter.
The service is in the early phases of a so-called Service Life Extension Program, or SLEP, to extend the combat life of about 300 F-16s by a decade or so. Indeed, with the upgrades, some aircraft are expected to still be flying in the 2030s -- long after the Air Force's fifth-generation F-35A Joint Strike Fighter is scheduled to enter service in 2016.
The F-16 has been undergoing durability testing at Naval Air Station Fort Worth, Texas, where many of the planes are based, to determine what modifications are needed to increase the aircraft's service life from 8,000 flying hours to as many as 12,000 flying hours.
"We strain and stress the aircraft in a manner that will simulate flight hours," Maj. Sean Tucker, F-16 program element monitor, told Military.com earlier this year. "We keep stressing it past a breaking point, allowing us to see what modifications we are going to need to do for our active fleet."
Due to automatic budget cuts known as sequestration, the Air Force has prioritized the SLEP program over another F-16 upgrade effort known as the Combat Avionics Program Extension Suite, or CAPES, designed to upgrade the aircraft's electronic warfare suite and intelligence broadcast system. The service proposed canceling the almost $2 billion CAPE program in its fiscal 2015 budget request.
The government of Taiwan is moving forward with the electronics upgrades and will be the first customer to buy them as part of the latest configuration of the aircraft known as F-16V. The enhancements include a new active electronically scanned array radar made by Northrop Grumman Corp, called the Scalable Agile Beam Radar, or SABR, which on Wednesday passed a key milestone in meeting Air Force requirements.
Meanwhile, the service plans to spend more than $650 million on the SLEP effort over the next five years, including $133 million in fiscal 2015, which begins Oct. 1, according to Pentagon budget documents.