Summary
We propose to supersede airworthiness directive (AD) 2015-08- 51 for Enstrom Helicopter Corporation (Enstrom) Model F-28A, 280, F- 28C, F-28C-2, F-28C-2R, 280C, F-28F, F-28F-R, 280F, 280FX, and 480 helicopters. AD 2015-08-51 requires an inspection of the main rotor spindle (spindle) and reporting the inspection results to the FAA. This proposed AD was prompted by additional reports of cracked spindles and would require establishing a life limit and a recurring inspection. These proposed actions are intended to prevent the unsafe condition on these products.