Nobody is accusing Boeing for the turbine failure. They are questioning Boeing’s drain tube track design failure. Source
According to the (Air Accidents Investigation Branch) AAIB, a high-pressure turbine blade had “fractured” in the 767’s right engine, damaging a further five blades.
Vibrations from the “out of balance” turbine led a section of the wing to rupture, causing fuel to leak out, which was then ignited by the engine’s exhaust.
The AAIB’s report questioned why the vibrations from a broken engine were sufficient to fracture the Boeing 767’s “slat track housing drain tube.”
At the end of its report, the AAIB said: “It is recommended that the Federal Aviation Administration requires the Boeing Airplane Company to demonstrate that following this serious incident, the design of the slat track housing drain tube on the Boeing 767 family of aircraft continues to comply with the certification requirements for large transport aircraft.”