AD NUMBER: 2009-11-01

MANUFACTURER: Eurocopter Deutschland GmbH (ECD) Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters
SUBJECT: Airworthiness Directive 2009-11-01

SUMMARY: We are superseding an existing airworthiness directive (AD) for the specified ECD model helicopters that currently requires initial and repetitive inspections of the main rotor blade (blade) upper and lower surfaces for bulging. This AD results from mandatory continuing airworthiness information (MCAI) issued by the European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, based on reported incidents in which a balance weight migrated toward the tip of the blade. The MCAI states that new blades have become available that are not fitted with lead balance weights. The MCAI states that only blades equipped with a lead balance weight may result in the unsafe condition. This AD retains the requirements of the current AD but limits the applicability to those part-numbered blades that are fitted with lead balance weights. The actions are intended to limit the applicability to those blades fitted with lead balance weights that could detach, migrate, and cause severe vibrations leading to blade failure and subsequent loss of control of the helicopter.
 

FMI: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/28C5114059D1CAF2862575C40054E165?OpenDocument