69-04-04 PILATUS: Amdt. 39-720. Applies to Model PC-6 airplanes, Serial Numbers 342 through 675, 2001 through 2009, 2012 through 2018, 2025 through 2035, 2040 and 2041.
Compliance required within the next 25 hours time in service after the effective date of this AD, unless already accomplished.
To prevent fatigue failure of the forward aileron mass balance attachment bolt P/N N-116 M5X40 (932.11.41.39), replace bolt on left and right aileron with new bolts of the same part number that have been supplied by the Pilatus Aircraft Works, Stans, Switzerland or Fairchild Hiller Corporation, Hagerstown, Maryland, after April 15, 1968 in accordance with Pilatus Service Bulletins No. 81 and 81A or later Swiss Federal Air Office-approved issue or an FAA approved equivalent.
This amendment becomes effective February 14, 1969.