The cracks can occur in the pylons that attach engines to wings. The problem came to light last month when American Airlines found cracks in at least two 767s during normal maintenance.
The FAA safety order affects 138 planes registered in the United States out of a global fleet of 314 planes. Aviation officials in other countries usually follow the FAA's lead on safety of U.S.-manufactured planes.
The order only applies to 767s that have the original pylon design. Boeing changed the design after the problem first became known.
FAA issued a safety order for these planes in 2005 requiring inspections for cracks every 1,500 flights. The new order accelerates that schedule to every 400 flights or every 90 days, whichever is later.
Besides American, other U.S. operators affected by the safety order are Continental Airlines, Delta Air Lines, FedEx Corp., United Airlines, United Parcel Service, US Airways, and ABX, formerly Airborne Express.
Statement from the FAA:
FAA Orders Inspections for Boeing 767 Pylons
The FAA is ordering U.S. operators of 138 Boeing 767 airplanes to reduce the initial pylon inspection time mandated in a September 22, 2005 Airworthiness Directive from 10,000 to 8,000 total flights. This inspection must be done within 400 flights after the most recent inspection required by the 2005 directive, or within 90 days, whichever occurs later.
The FAA is also reducing the interval for repetitive inspections for cracking of the pylon midspar structural fittings and an adjacent structure from 1,500 to every 400 flights thereafter. There is also an option for replacing the fittings instead of conducting the inspections.
Since the 2005 Airworthiness Directive (AD), the FAA has received two reports of cracking of the midspar structural fitting on Boeing 767 pylons. The pylon attaches the engine to the wing. Undetected cracking could lead to fracture of the structural components, damage to the pylon, and separation of the engine from the wing.
The Immediately Adopted AD affects 138 U.S.-registered airplanes out of 314 worldwide. The total cost to U.S. operators is approximately $46,920. The AD affects only those 767 models that have the original pylon design. Boeing has improved the design of the 767 pylon and those aircraft with the improved pylon designs are not included in this AD.