Action
Notice of proposed rulemaking (NPRM).
Summary
This document proposes adopting a new airworthiness directive (AD) for Bell Helicopter Textron, Inc., (Bell) Model 412 and 412EP helicopters. This proposal would require creating a component history card or equivalent record and begin counting and recording the number of accumulated landings for each high aft crosstube assembly (crosstube). Also, this proposal would require installing "caution" decals regarding towing of a helicopter at or above 8,900 pounds. This proposal would also require confirming the crosstube is within the horizontal deflection limits and replacing it if it is not. This proposal would also require a recurring fluorescent penetrant inspection (FPI) of each crosstube and upper center support for a crack, any corrosion, nick, scratch, dent, or any other damage. This proposal would require repairing damaged crosstubes and upper center supports that are within acceptable limits, reworking crosstubes by bonding on abrasion strips, and replacing each unairworthy crosstube with an airworthy crosstube. This proposal is prompted by analysis of the crosstubes conducted as a result of recent field failures and corrosion problems of the affected crosstubes. The actions specified by this proposed AD are intended to prevent failure of a crosstube, collapse of the landing gear, and subsequent loss of control of the helicopter.