AD NUMBER: 2018-02-01

PRODUCT: Enstrom Helicopter Corporation (Enstrom) Model F-28A, 280, F-28C, F-28C-2, F-28C-2R, 280C, F-28F, F28F-R, 280F, 280FX, and 480 helicopters.

ACTION: Final Rule.

SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2015-08-51 for the aircraft listed above.

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.

DATES: This AD is effective February 21, 2018.

COST: The FAA estimates that this AD affects 323 helicopters of U.S. Registry. Operators may incur the following costs in order to comply with this AD. Labor costs are estimated at $85 per work-hour.

• Inspecting the spindles takes about 15 work-hours for an estimated cost of $1,275 per helicopter and $411,825 for the U.S. fleet per inspection cycle.
• Replacing a cracked spindle costs $8,164 for parts and no additional work-hours.
• Replacing a set of three spindles that have reached their life limit takes about 14 work-hours and parts will cost $17,500 for a total cost of $18,690 per helicopter.

FMI: AD