Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede an existing airworthiness directive (AD) for Agusta Model AB139 and AW139 helicopters. The existing AD currently requires establishing a revised life limit for each tail rotor blade (blade), updating the helicopter's historical records, repetitively inspecting each blade for a crack, and replacing certain blades. Since we issued that AD, the manufacturer has improved the design of the blades using different materials and established life limits for each newly-designed blade. This proposed AD would expand the applicability to include the newly-designed blades and establish their life limits. This proposed AD would also retain the requirement to inspect each blade for a crack and, if there is a crack, replace each blade with an airworthy blade. The proposed actions are intended to detect a crack in a blade to prevent failure of a blade and subsequent loss of control of the helicopter.