The latest airworthiness directive (AD) issued by the Federal Aviation Administration (FAA) of the United States (US) aims to stop the possible loss of the horizontal stabilizer on a Boeing 777.
On May 26, 2023, the FAA published the AD in response to allegations of “cracks found in the pivot bulkhead forward outer chord of a certain station”. The FAA published the directive to address the probable fracture of the pivot bulkhead front outer chord after discovering “higher bending stresses across the chord than originally assessed” during its investigation.
“The FAA is issuing this AD to address cracking in the STA 2370 pivot bulkhead forward outer chord. Such cracking, if not detected and corrected, could result in a severed pivot bulkhead outer chord, loss of horizontal stabilizer control, and loss of controllability of the airplane,” the regulator outlined.
According to the directive, airlines flying Boeing 777-200, 777-200LR, 777-300, 777-300ER, and 777F aircraft must repeatedly check the pivot bulkhead forward outer chord of specific stations and longeron fittings for cracking and take any necessary corrective action.
According to the FAA, the regulation will have an impact on 223 US-registered aircraft. Operators will pay $4,390 for each inspection, $850 for labor, and $3,540 for parts, for thorough and HFEC inspections.
In the event of an on-condition following an inspection, the FAA has no method of determining the number of aircraft that will need to be replaced, but it estimates the cost to be $40,950 per aircraft per side ($3,230 for labor and $37,720 for parts). Additionally, operators will have to pay $2,380 in labor costs for each side of a Boeing 777 if the inspection results in the need for an on-condition thorough and open-hole HFEC inspection.
The Boeing Alert Requirements Bulletin (RB) 777-53A0098 RB, issued April 5, 2022, specifies the appropriate actions and the appropriate periods for compliance.