Summary
We propose to supersede airworthiness directive (AD) 2001-13- 51 for Bell Model 206L-4, 407, and 427 helicopters. AD 2001-13-51 currently requires inspecting certain driveshafts for a crack, a loose bolt or nut, or red powder residue and replacing a driveshaft if there is a crack, a loose bolt or nut, or red powder residue. AD 2001-13-51 also requires notifying the FAA within 10 days if a crack is found in the driveshaft. Since we issued AD 2001-13-51, the Model 429 helicopter has been certificated, and the reporting requirement is no longer necessary. This proposed AD would retain the inspection requirement of AD 2001-13-51, expand the applicability to include the Model 429 helicopter, and remove the reporting requirement. These proposed actions are intended to prevent failure of a driveshaft, loss of drive to the main rotor system, and a subsequent emergency landing.