The FAA issued a new airworthiness directive Monday requiring inspections of fuel tank sealant on certain Boeing 787 Dreamliners after determining that required production inspections could not be verified. The directive applies to certain 787-8, 787-9 and 787-10 aircraft and takes effect Dec. 7.
Fuel Tank Safety Concerns
The issue involves sealant installations within the center wing fuel tank that lacked Boeing documentation confirming required visual and adhesion inspections during manufacturing. Under the directive, operators must examine sealant installations in the left, right and center wing side-of-body areas, conduct adhesion tests and complete repairs where necessary.
“The unsafe condition, if not addressed, could result in development of an ignition source within the fuel tank volume and a risk of a fuel tank explosion during a lightning strike event,” the FAA stated in the directive.
The agency previously raised similar concerns involving fuel tank fastener seals on Boeing 777 aircraft.
Inspection Costs and Requirements
The FAA estimates the directive affects 60 U.S.-registered aircraft. Required inspections and adhesion testing are expected to take approximately 34 work-hours per airplane, costing an estimated $2,890 each, or $173,400 across the affected U.S. fleet. Those estimates exclude additional repairs, for which the agency said it lacked sufficient cost data. Some expenses may be covered under Boeing’s warranty.
During the rulemaking process, Boeing and American Airlines requested changes to the repair requirements, while American also sought clarification of the inspection areas. The FAA accepted Boeing’s proposal to permit repairs performed under specified airworthiness limitations and clarified the required adhesion testing locations. The agency also confirmed that the required sealant inspections are being performed during production on aircraft outside the directive’s scope.
The rule follows the FAA’s July decision to restore Boeing’s authority to issue airworthiness certificates for newly produced 787 and 737 MAX aircraft.
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