97-23-04: Fuel Tank Vent Valves

97-23-04 PILATUS AIRCRAFT, LTD.: Amendment 39-10192; Docket No. 97-CE-95-AD. Applicability: Models PC-12 and PC-12/45 airplanes; serial numbers 101 through 186, certificated in any category. NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it. Compliance: Required within the next 10 hours time-in-service (TIS) after the effective date of this AD, unless already accomplished. To prevent the fuel tank inward vent valve from freezing, which, if followed by a cold soak at altitude, could result in wing airfoil distortion and structural damage with consequent degradation of the airplane's handling qualities, accomplish the following: (a) Replace the fuel tank vent valves with modified fuel tank vent valves in accordance with the Accomplishment Instructions section of Pilatus Service Bulletin No. 28-003, Revision 1, dated September 30, 1997. (b) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. (c) An alternative method of compliance or adjustment of the compliance time that provides an equivalent level of safety may be approved by the Manager, Small Airplane Directorate, FAA, 1201 Walnut, suite 900, Kansas City, Missouri 64106. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Small Airplane Directorate. NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Small Airplane Directorate. (d) The replacement required by this AD shall be done in accordance with Pilatus Service Bulletin No. 28-003, Revision 1, dated September 30, 1997. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Pilatus Aircraft Ltd., CH-6370 Stans, Switzerland. Copies may be inspected at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.NOTE 3: The subject of this AD is addressed in Swiss AD HB 97-432A, dated October 3, 1997. (e) This amendment becomes effective on December 1, 1997.