AD 98-16-16

This amendment adopts a new airworthiness directive (AD) that applies to certain Pilatus Aircraft Ltd. Model PC-7 airplanes. This AD requires replacing the seal unit on both main landing gear (MLG) legs and the nose landing gear (NLG) leg. This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. The actions specified by this AD are intended to prevent MLG or NLG failure caused by deterioration of a MLG or NLG leg seal unit, which could result in damage to the airplane or airplane control problems during takeoff, landing, or taxi operations.

Final rule.

98-16-16 PILATUS AIRCRAFT LTD.: Amendment 39-10692; Docket No. 98-CE-30-AD.

Applicability: Model PC-7 airplanes, all manufacturer serial numbers (MSN) up to and including MSN 609, 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 (d) 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 inthe body of this AD, unless already accomplished.

To prevent main landing gear (MLG) or nose landing gear (NLG) failure caused by deterioration of a MLG or NLG leg seal unit, which could result in damage to the airplane or airplane control problems during takeoff, landing, or taxi operations, accomplish the following:

(a) Within the next 100 hours time-in-service after the effective date of this AD, replace the seal unit on both MLG legs and the NLG leg in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of Pilatus Service Bulletin No. 32-018, dated March 6, 1998.

(b) As of the effective date of this AD, no person may install, on an affected airplane, a MLG leg or NLG leg that does not have an improved seal unit installed in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of Pilatus Service Bulletin No. 32-018, dated March 6, 1998.

(c) 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.

(d) 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.

(e) Questions or technical information related to Pilatus Service Bulletin No. 32-018, dated March 6, 1998, should be directed to Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 Stans, Switzerland; telephone: +41 41 619 6233; facsimile: +41 41 610 3351. This service information may beexamined at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.

(f) The replacements required by this AD shall be done in accordance with Pilatus Service Bulletin No. 32-018, dated March 6, 1998. 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., Customer Liaison Manager, CH-6371 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 98-069, dated March 23, 1998.

(g) This amendment becomes effective on September 21, 1998.

Events Leading to the Issuance of This AD
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to certain Pilatus Aircraft Ltd. Model PC-7 airplanes was published in the Federal Register as a notice of proposed rulemaking (NPRM) on May 29, 1998 (63 FR 29360). The NPRM proposed to require replacing the seal unit on both MLG legs and the NLG leg. Accomplishment of the proposed action as specified in the NPRM would be in accordance with Pilatus Service Bulletin No. 32-018, dated March 6, 1998.

The NPRM was the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposed rule or the FAA's determination of the cost to the public.

The FAA's Determination
After careful review of all available information related to the subject presented above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for minor editorial corrections. The FAA has determined that these minor corrections will not change the meaning of the AD and will not add any additional burden upon the public than was already proposed.

Cost Impact
The FAA estimates that 5 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 8 workhours per airplane to accomplish this action, and that the average labor rate is approximately $60 an hour. Parts cost approximately $932 per airplane. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $7,060, or $1,412 per airplane.

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.

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) 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 final evaluation prepared for this action is contained 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, 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 adding a new airworthiness directive (AD) to read as follows: