AD 99-17-08

This amendment adopts a new airworthiness directive (AD) that applies to certain Pilatus Aircraft Ltd. (Pilatus) Models PC-12 and PC-12/45 airplanes. This AD requires modifying the generator 2 excitation by removing certain diodes and installing a new 5-amp circuit breaker and suppression filter. 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 damage to electrical components if the generator 2 is not switched off prior to engine shutdown and it overheats, which could result in loss of electrical power to certain critical airplane components.

Final rule.

99-17-08 Pilatus Aircraft Ltd.: Amendment 39-11256; Docket No. 99-CE-10-AD.

Applicability: Models PC-12 and PC-12/45 airplanes, manufacturer serial numbers (MSN) 101 through 260, 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 in the body of this AD, unless already accomplished.

To prevent damage to electrical components if the generator 2 is not switched off prior to engine shutdown and it overheats, which could result in loss of electrical power to certain critical airplane components, accomplish the following:

(a) Within the next 100 hours time-in-service (TIS) after the effective date of this AD, modify the generator 2 excitation by removing certain diodes and installing a new 5-amp circuit breaker and suppression filter. Perform these actions in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of Pilatus Service Bulletin No. 24-012, dated February 19, 1999.

Note 2: The affected airplanes incorporate one of the following generators:

--a BOSCH Generator 2, part number (P/N) 524.32.12.158. This generator is installed at the factory on Pilatus Models PC-12 and PC-12/45 airplanes beginning with MSN 231 and could be installed on airplanes with a MSN in the range of 101 through 230 by incorporating Pilatus Service Bulletin No. 24-010, dated September 28, 1998; or

--an ELECTRO SYSTEMS Generator 2, P/N 978.87.24.121, with Pilatus Service Bulletin No. 24-009 (installation of support bracket and cut-out relay) incorporated. This generator is installed at the factory on Pilatus Models PC-12 and PC-12/45 airplanes with a MSN in the range of 101 through 230. AD 99-06-17, Amendment 39-11081 (64 FR 13882, March 23, 1999), requires installing the support bracket and cut-out relay specified in Pilatus Service Bulletin No. 24-009, dated September 23, 1998, on Pilatus Models PC-12 and PC-12/45 airplanes with a MSN in the range of 101 through 180. This service bulletin is incorporated at the factory on airplanes with a MSN in the range of 181 through 230.

(b) As of the effective date of this AD, no person may install, on any affected airplane, a generator 2 that does not have the modification referenced in paragraph (a) of this AD incorporated.

(c) Special flight permitsmay 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 3: 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. 24-012, dated February 19, 1999, should be directed to Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 Stans, Switzerland; telephone: +41 41 619 63 19; facsimile: +41 41 610 33 51. 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.

(f) The modification required by this AD shall be done in accordance with Pilatus Service Bulletin No. 24-012, dated February 19, 1999. 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 4: The subject of this AD is addressed in Swiss AD HB 99-143, dated February 19, 1999.

(g) This amendment becomes effective on October 4, 1999.

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 Models PC-12 and PC-12/45 airplanes was published in the Federal Register as a notice of proposed rulemaking (NPRM) on June 14, 1999 (64 FR 31758). The NPRM proposed to require modifying the generator 2 excitation by removing certain diodes and installing a new 5-amp circuit breaker and suppression filter. Accomplishment of the proposed action as specified in the NPRM would be required in accordance with Pilatus Service Bulletin No. 24-012, dated February 19, 1999.

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 69 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 5 workhours per airplane to accomplish this action, and that the average labor rate is approximately $60 an hour. Parts will be provided at no cost to the owners/operators of the affected aircraft. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $20,700, or $300 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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: