The US Federal Aviation Administration has mandated that airlines with Boeing 737NG aircraft that have completed a high rate of flight cycles must re-inspect hardware known as "pickle forks" that connect a wing to a fuselage.
Boeing notified the FAA that one operator found a crack outside of the original section of the fuselage the FAA had mandated for inspection in October.
Today, the FAA published an airworthiness directive requiring that 737NGs that have completed 30,000 flight cycles be re-inspected within 60 days, expanding the initial search area for cracks from two fasteners to eight fasteners on each side of the aircraft. Carriers must inspect 737NGs that have completed 22,600 flight cycles within their next 1,000 flight cycles. The order impacts US-registered 737NGs, including -600, -700, -800 and -900 series aircraft.
The additional inspections are underway, Boeing says in a statement.
"We regret the impact to our customers and have a repair plan in place to address any findings," Boeing states. "Less than 5% of the 1,200 airplanes that have undergone the initial inspection were found to have the cracking issue. The secondary issue has been discovered on three in-service airplanes and one airplane that was undergoing maintenance in preparation for a modification."
Replacing pickle forks can be costly also because aircraft interiors must be stripped out, including side panels and fixtures.
The FAA ordered the original inspections on 2 October after Boeing discovered cracks on pickle fork hardware of 737-800s undergoing passenger-to-freighter conversions in China.
Airlines impacted include Qantas, Ryanair, Southwest Airlines, Gol, and Indonesian carriers Sriwijaya Air and Garuda.