[Federal Register Volume 63, Number 57 (Wednesday, March 25, 1998)] [Proposed Rules] [Pages 14385-14387] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 98-7672] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. 97-CE-09-AD] RIN 2120-AA64 Airworthiness Directives; Pilatus Aircraft Ltd. PC-6, PC-6/A, PC- 6/B, and PC-6/C Series Airplanes AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes to adopt a new airworthiness directive (AD) that would apply to certain Pilatus Aircraft Ltd. (Pilatus) PC-6, PC-6/A, PC-6/B, and PC-6/C series airplanes equipped with turbo-prop engines. The proposed action would require modifying the fuel system to improve the venting between the collector tank, the main wing tanks, and the engine. The proposed AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. The actions specified by the proposed AD are intended to prevent engine fuel starvation during maximum climb and descent caused by poor fuel tank venting with low fuel levels, which, if not corrected, could result in a loss of engine power during critical phases of flight. DATES: Comments must be received on or before April 27, 1998. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 97-CE-09-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106. Comments may be inspected at this location between 8 a.m. and 4 p.m., Monday through Friday, holidays excepted. Service information that applies to the proposed AD may be obtained from Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6370 Stans, Switzerland; telephone: +41 41-6196 233; facsimile: +41 41-6103 351. This information also may be examined at the Rules Docket at the address above. FOR FURTHER INFORMATION CONTACT: Mr. Roman T. Gabrys, Aerospace Engineer, FAA, Small Airplane Directorate, Airplane Certification Service, 1201 Walnut, suite 900, Kansas City, Missouri 64106; telephone (816) 426-6932; facsimile (816) 426-2169. SUPPLEMENTARY INFORMATION: Comments Invited Interested persons are invited to participate in the making of the proposed 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, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed 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 proposal will be filed in the Rules Docket. Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket No. 97-CE-09-AD.'' The postcard will be date stamped and returned to the commenter. Availability of NPRMs Any person may obtain a copy of this NPRM by submitting a request to the [[Page 14386]] FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 97-CE-09-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106. Discussion The Federal Office for Civil Aviation (FOCA), which is the airworthiness authority for Switzerland, notified the FAA that an unsafe condition may exist on certain Pilatus PC-6, PC-6/A, PC-6/B, and PC-6/C series airplanes. The FOCA reports that there have been incidents of engines stopping during flight on these airplanes during parachute dropping and sky-diving missions. The investigation disclosed that the circumstances leading to the incidents were: frequently running at minimum fuel levels; making long and steep climbs and descents; and, making immediate landing and take-off turn-arounds with the engine running. Operating these airplanes in this manner may not allow the collector fuel tank to completely refill, especially if the fuel level is low. Under sustained, maximum achievable climb and descent altitudes, the low fuel level, combined with the current fuel venting system, allows air inclusion in the fuel lines. These conditions, if not corrected, could result in engine fuel starvation and loss of engine power during critical phases of flight. Relevant Service Information Pilatus has issued Service Bulletin No. PC-6-SB-171, dated October 18, 1995, which specifies procedures for modifying the airplane fuel system, which improves the venting of the collector tank between the main wing tanks and the engine. This modification would assist in eliminating the possibility of air inclusion in the fuel lines while operating at maximum climb and descent altitudes. This service information also recommends inserting Airplane Flight Manual (AFM) Temporary Revision dated October 18, 1995, to remind the pilot to avoid repeated prolonged descents. The FOCA classified this service bulletin as mandatory and issued Swiss AD HB 95-451, dated November 1, 1995, in order to assure the continued airworthiness of these airplanes in Switzerland. The FAA's Determination These airplane models are manufactured in Switzerland and are type certificated for operation in the United States under the provisions of Sec. 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 has kept the FAA informed of the situation described above. The FAA has examined the findings of the FOCA, reviewed all available information, including the service information referenced above, 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 the Proposed AD Since an unsafe condition has been identified that is likely to exist or develop in other Pilatus PC-6, PC-6/A, PC-6/B, and PC-6/C series airplanes of the same type design registered in the United States, the FAA is proposing AD action. The proposed AD would require modifying the airplane's fuel venting system. Accomplishment of the proposed modification would be in accordance with Pilatus PC-6 Service Bulletin No. PC-6-SB-171, dated October 18, 1995. Differences Between the Service Information, the FOCA AD, and the Proposed AD Action The manufacturer recommends the modification of the fuel venting system and the insertion of a temporary revision to the AFM, and FOCA requires this temporary AFM insertion and modification for airplanes operated in Switzerland. The Swiss AD requires the AFM revision be accomplished prior to further flight and requires the revision to remain in the AFM until the venting modification is accomplished. The FOCA requires that the modification be accomplished within 90 days from receipt of the service bulletin. The FAA does not propose to require insertion of the temporary AFM revision. The FAA proposes the modification of the fuel venting system and the calendar compliance time that is required by the Swiss AD. Cost Impact The FAA estimates that 29 airplanes in the U.S. registry would be affected by the proposed AD, that it would take approximately 10 workhours per airplane to accomplish the proposed action, and that the average labor rate is approximately $60 an hour. Parts cost approximately $614 per airplane. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $35,206 or $1,214 per airplane. Regulatory Impact The regulations proposed herein would 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 proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. For the reasons discussed above, I certify that this action (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the draft regulatory evaluation prepared for this action has been placed in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES. List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Safety. The Proposed Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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. Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: Pilatus Aircraft Ltd.: Docket No. 97-CE-09-AD. Applicability: Models PC-6, PC-6-H1, PC-6-H2, PC-6/350, PC-6/ 350-H1, PC-6/350-H2, PC-6/A, PC-6/A-H1, PC-6/A-H2, PC-6/B-H2, PC-6/ B1-H2, PC-6/B2-H2, PC-6/B2-H4, PC-6/C-H2, and PC-6/C1-H2 airplanes (serial numbers 001 through 915), certificated in any category, that are equipped with turbo-prop engines. 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 [[Page 14387]] 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 3 calendar months after the effective date of this AD, unless already accomplished. To prevent engine fuel starvation during maximum climb and descent caused by poor fuel tank venting with low fuel levels, which, if not corrected, could result in a loss of engine power during critical phases of flight, accomplish the following: (a) Modify the fuel venting system in accordance with the Accomplishment Instructions section in Pilatus PC-6 Service Bulletin No. PC-6-SB-171, dated October 18, 1995. (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, 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) Questions or technical information related to Pilatus Service Bulletin No. PC-6-SB-171, dated October 18, 1995, should be directed to Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6370 Stans, Switzerland; telephone: +41 41-6196 233; facsimile: +41 41- 6103 351. 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. Note 3: The subject of this AD is addressed in Swiss AD HB 95- 451, dated November 1, 1995. Issued in Kansas City, Missouri, on March 18, 1998. Michael Gallagher, Manager, Small Airplane Directorate, Aircraft Certification Service. [FR Doc. 98-7672 Filed 3-24-98; 8:45 am] BILLING CODE 4910-13-P