66-01-03 PILATUS: Amdt. 39-173, Part 39, Federal Register December 24, 1965. Applies to Model PC-6 Series Airplanes, Serial Numbers 515, 522, and 524 through 580.
Compliance required as indicated, unless already accomplished.
To prevent further instances of fuel flow restriction, accomplish the following:
(a) Within the next 10 hours' time in service after the effective date of this AD, inspect fuel shutoff valve P/N 321-ITX 6D for correct installation of the valve plug in accordance with Pilatus Service Bulletin No. 36, dated September 1965, or later Swiss Federal Air Office- approved revision. If the valve plug protrudes more than 2mm. (0.078 inch), before further flight, replace the valve with a new valve P/N 6238.124.
(b) Within the next 60 hours' time in service after the effective date of this AD, replace fuel shutoff valve P/N 321-ITX 6D with a new valve P/N 6238.124, in accordance with Pilatus Service Bulletin No. 36, dated September 1965, or later Swiss Federal Air Office- approved revision.