Cracks in the engine pylons of three American Airlines Boeing 767’s are prompting concerns over the need of more frequent inspections of Boeing 767’s. The FAA says American and Boeing are looking for the cause of the cracking, which was discovered during routine metallurgical tests. Boeing is preparing a service bulletin establishing new guidelines for inspecting this particular part, over and above the every “1500 flights” which stands now. The flight which originally caught American’s attention had developed the cracks during the last 500 flights since its last pylon inspection. Caution about underlying structural issues is being addressed.
The preliminary conclusion is that certain maintenance practices may play in the underlying cause of the cracking. A known issue is that some of the cracks arise from holes used to install bolts, implying that the bolt holes may compromise the structural integrity, or at least affect the pylon’s longevity; and may affect “fail-safe” design.
The FAA has not yet mandated inspection of 767 other jets operated by other carriers, nor have they determined if winglets are a contributing factor.
Aeroflot flight SU-1451 made an emergency landing in Novosibirsk, Russia, on September 6th.