Airworthiness Directives; British Aerospace Model B.121 Series 1, 2, and 3 Airplanes

This amendment adopts a new airworthiness directive (AD) that applies to certain British Aerospace Model B.121 Series 1, 2, and 3 airplanes. This AD requires installing an inspection opening in the area of the main spar web, repetitively inspecting the area at the main spar web for cracks, and repairing or replacing any cracked part. This AD also requires installing nuts of improved design at the wing to fuselage main-spar attachment fittings. This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for the United Kingdom. The actions specified by this AD are intended to prevent structural failure of the main spar web area caused by fatigue cracking or separation of the wing caused by loose nuts at the wing to fuselage main-spar attachment fittings, which could result in loss of control of the airplane.