Airworthiness Directive · Amendment 39-19154 · Main rotor head
The Enstrom Helicopter Corporation Helicopters
This AD applies to Enstrom Model F-28A, 280, F-28C, F-28C-2, F-28C-2R, 280C, F-28F, F-28F-R, 280F, and 280FX helicopters, all serial numbers; and Enstrom Model 480 helicopters, serial numbers 5001 through 5006; with a main rotor spindle (spindle) part number (P/N) 28-14282-11 or 28-14282-13, installed, certificated in any category.
We are superseding Airworthiness Directive (AD) 2015-08-51 for the 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 required an inspection of the main rotor spindle (spindle) and reporting the inspection results to the FAA. This new AD was prompted by additional reports of cracked spindles and requires establishing a life limit and a recurring inspection. The actions of this AD are intended to prevent the unsafe condition on these products.
You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.
(1) Before further flight, remove from service any spindle P/N 28-14282-11 or 28-14282-13 that has 1,500 or more hours time-in-service (TIS). If the hours TIS of a spindle is unknown, use the TIS of the helicopter. Thereafter, remove from service any spindle P/N 28-14282-11 or 28-14282-13 before accumulating 1,500 hours TIS.
(2) For each spindle with 500 or more hours TIS, using the hours TIS of the helicopter if the hours TIS of the spindle is unknown:
(i) Before further flight, unless already done within the last 500 hours TIS, conduct a magnetic particle inspection (MPI) of the spindle for a crack, paying particular attention to the threaded portion of the spindle. The MPI of the spindle must be conducted by a Level II or Level III inspector qualified in the MPI in the Aeronautics Sector according to the EN4179 or NAS410 standard or equivalent. If there is a crack in the spindle, replace it with an airworthy spindle before further flight.
(ii) Thereafter at intervals not to exceed 500 hours TIS, repeat the MPI specified in paragraph (f)(2)(i) of this AD.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
