AD 98-11-01

This amendment supersedes Airworthiness Directive (AD) 97-23-04, which currently requires replacing the fuel tank vent valves with modified fuel tank vent valves on certain Pilatus Aircraft Ltd. (Pilatus) Models PC-12 and PC-12/45 airplanes. This AD retains the fuel tank vent valves replacement required by AD 97-23-04, and requires drilling a 4.8 millimeter (0.1875 inch) hole in each fuel filler cap. This AD also requires inserting a temporary revision in the Pilot's Operating Handbook (POH) that specifies checking to assure that the fuel filler cap hole is clear of ice and foreign objects. This AD is the result of mandatory continued airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. The actions specified by this AD are intended 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.

Final rule; request for comments.

98-11-01 PILATUS AIRCRAFT, LTD.: Amendment 39-10528; Docket No. 98-CE-40-AD; Supersedes AD 97-23-04, Amendment No. 39-10192.

Applicability: Models PC-12 and PC-12/45 airplanes; serial numbers 101 through 230, 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 (e) 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 as indicated in the body 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) Within the next 10 hours time-in-service (TIS) after December 1, 1997 (the effective date of AD 97-23-04), 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) Within the next 10 hours TIS after the effective date of this AD, accomplish the following:

(1) Drill a 4.8 millimeter (0.1875 inch) hole in each fuel filler cap in accordance with the Accomplishment Instructions section of Pilatus Service Bulletin No. 28-004, dated March 27, 1998.

(2) Insert a temporary revision (as referenced in Pilatus Service Bulletin 28-004, dated March 27, 1998) into the Pilot's Operating Handbook (POH) that specifies checking to assure that the fuel filler cap hole is clear of ice and foreign objects. This document is entitled "PC-12 Pilot's Operating Handbook, Pilatus Report No. 01973-001, Temporary Revision, Fuel Filler Cap, dated March 27, 1998."

(c) Inserting the POH revision, as required by paragraph (b)(2) of this AD, may be performed by the owner/operator holding at least a private pilot certificate as authorized by section 43.7 of the Federal Aviation Regulations (14 CFR 43.7), and must be entered into the aircraft records showing compliance with this AD in accordance with section 43.9 of the Federal Aviation Regulations (14 CFR 43.9).

(d) 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.

(e) 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.

(1) 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.

(2) Alternative methods of compliance approved in accordance with AD 97-23-04 (superseded by this action) are considered approved as alternative methods of compliance for this AD.

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.

(f) Questions or technical information related to Pilatus Service Bulletin No. 28-004, dated March 27, 1998, should be directed to Pilatus Aircraft Ltd., CH-6370 Stans, Switzerland. This service information may be examined at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.

(g) The replacement required by this AD shall be done in accordance with Pilatus Service Bulletin No. 28-003, Revision 1, dated September 30, 1997. The drilling required by this AD shall be done in accordance with Pilatus Service Bulletin No. 28-004, dated March 27, 1998.

(1) The incorporation by reference of Pilatus Service Bulletin No. 28-003, Revision 1, dated September 30, 1997, was previously approved by the Director of the Federal Register as of December 1, 1997 (62 FR 59993, November 6, 1997).

(2) The incorporation by reference of Pilatus Service Bulletin No. 28-004, dated March 27, 1998, was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.

(3) Copies of these service bulletins 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, and Swiss AD HB 98-086, dated March 31, 1998.

(h) This amendment supersedes AD 97-23-04, Amendment No. 39-10192.

(i) This amendment becomes effective on June 7, 1998.

Discussion
AD 97-23-04, Amendment 39-10192 (62 FR 5993, November 6, 1997), currently requires replacing the fuel tank vent valves with modified fuel tank vent valves on certain Pilatus Models PC-12 and PC-12/45 airplanes. AD 97-23-04 was the result of a report from the Federal Office for Civil Aviation (FOCA), which is the airworthiness authority for Switzerland, of an instance of abnormal automatic engagement of the fuel booster pumps during normal operation of a Pilatus Model PC-12 airplane. The FOCA's investigation revealed that the fuel tank inward vent valves may fail in the closed position under certain conditions. Moisture ingestion, followed by cold soak, can lead to the fuel tank inward vent valve freezing.

This condition, if not corrected, could result in wing airfoil distortion and structural damage with consequent degradation of the airplane's handling qualities.

Actions Since Issuance of Previous Rule

The FOCA recently notified the FAA that an unsafe condition may still exist on certain Pilatus Models PC-12 and PC-12/45 airplanes, even after compliance with AD 97-23-04. The FOCA reports that the inward vent valve of the fuel tank froze closed on one of the affected airplanes that was in compliance with the fuel tank vent valves replacement requirement of AD 97-23-04. This resulted in permanent structural damage to the wing skins and ribs.

Relevant Service Information

Pilatus has issued Service Bulletin No. 28-004, dated March 27, 1998, which specifies procedures for drilling a 4.8 millimeter (0.1875 inch) hole in each fuel filler cap. This service bulletin also references a temporary revision to the POH that specifies checking to assure that the fuel filler cap hole is clear of ice and foreign objects. This document is entitled "PC-12 Pilot's Operating Handbook, Pilatus Report No. 01973-001, Temporary Revision, Fuel Filler Cap, dated March 27, 1998."

The FOCA of Switzerland classified this service bulletin as mandatory and issued Swiss AD HB 98-086, dated March 31, 1998, in order to assure the continued airworthiness of these airplanes in Switzerland.

The FAA's Determination

This airplane model is manufactured in Switzerland and is type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the FOCA of Switzerland has kept the FAA informed of the situation described above.

The FAA has examined the findings of the FOCA of Switzerland; reviewed all available information, including the service bulletin referenced in this document; and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Explanation of the Provisions of This AD

Since an unsafe condition has been identified that is likelyto exist or develop in other Pilatus Models PC-12 and PC-12/45 airplanes of the same type design registered for operation in the United States, the FAA is issuing an AD to supersede AD 97-23-04. This AD retains the fuel tank vent valves replacement required by AD 97-23-04, and requires drilling a 4.8 millimeter (0.1875 inch) hole in each fuel filler cap. This AD also requires inserting the following temporary revision to the POH that specifies checking to assure that the fuel filler cap hole is clear of ice and foreign objects:

"PC-12 Pilot's Operating Handbook, Pilatus Report No. 01973-001,
Temporary Revision, Fuel Filler Cap, dated March 27, 1998."

Accomplishment of the actions specified in this AD is required in accordance with the instructions in Pilatus Service Bulletin No. 28-004, dated March 27, 1998.

Determination of the Effective Date of the AD

Since a situation exists (possible wing airfoil distortion and structural damage with consequent degradation ofthe airplane's handling qualities) that requires the immediate adoption of this regulation, it is found that notice and opportunity for public prior comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves requirements affecting immediate flight safety and, thus, was not preceded by notice and opportunity to comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket No. 98-CE-40-AD." The postcard will be date stamped and returned to the commenter.

Regulatory Impact

The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and is not a significant regulatory action under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket (otherwise, an evaluation is not required). A copy of it, iffiled, may be obtained from the Rules Docket.

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.

39.13 [Amended]
2. Section 39.13 is amended by removing Airworthiness Directive (AD) 97-23-04, Amendment No. 39-10192 (62 FR 59993, November 6, 1997), and by adding a new AD to read as follows: