The FAA has found that all Boeing 747 variants from the B747-100 to the B747-8 are inadequately protected against lightning strikes. This applies both to passenger and cargo versions of the highly successful model built by the U.S. manufacturer. In a directive (DOC: FAA-2023-2228 / AD-2023-01095-T), the U.S. regulator, Federal Aviation Administration (FAA), has now instructed all operators of the aircraft to inspect lightning protection features in the fuel tanks of all B747 variants.
The directive was issued following reports from Boeing that lightning protection components in the engine fuel systems of this aircraft are degrading faster than expected. As consequence of this warning, the FAA has informed all B747 operators that this is “an urgent safety issue, as all lightning protection features of the fuel supply system now have evidence of compromise.” FAA’s document further reads: “The lightning protection features for the engine fuel feed system could fail without being detected [during routine checks, HS].” Flights at an altitude between 8,000 and 12,000 meters are particularly affected.
Explosions cannot be excluded
The risk involves components designed to prevent sparks in the fuel tubes that penetrate the B747’s fuel tanks. During inspections, Boeing technical experts detected that the “bonding jumpers”, responsible for creating safe paths for electricity, are failing at an excessive rate. The malfunction of these components could result in a lack of lightning protection, which, combined with flammable fuel vapors, might cause fuel tanks to explode. “This cannot be excluded,” warns the FAA.
The Airworthiness Directive comes into effect on 15DEC23. Operators of B747s will have 90 days to inspect their passenger variants and 120 days for the cargo versions. Further inspections must be carried out annually.
Almost 500 B747s are still in service or mothballed at airports
The FAA’s directive is considered a final order, indicating the urgency of the situation. It applies to a total of 211 B747 aircraft registered in the U.S., and hundreds of B747 variants registered elsewhere, from the aging B747-100 variant to the modern B747-8.
In total, there are 495 B747 aircraft in service or stored worldwide, with Atlas Air Worldwide Holdings and its affiliates, particularly Polar Air, operating the largest fleet, consisting of 56 units. Other U.S. carriers with considerable B747 fleets include UPS (41), Kalitta Air (24), and National Airlines (8). In Europe, Cargolux is a main operator of B747 freighters. Further east, Silk Way West Airlines relies on Jumbo freighters, so do Cathay Pacific, Japanese carrier ANA Cargo, Emirates SkyCargo, and Air China Cargo, to name but a few.
The inspection that has now been ordered, also affects the last two jumbos built and delivered by frame maker Boeing: B747-8 freighters delivered to Atlas Air in FEB22, and operated under an ACMI contract by logistics giant, Kuehne+Nagel.
