AD 99-03-06

This amendment adopts a new airworthiness directive (AD), applicable to all Short Brothers Model SD3-60 SHERPA series airplanes, that requires a one-time visual inspection to determine the part number of the power control cable assemblies and pulleys of the engine controls; and replacement of the power control cable assemblies and pulleys (as applicable) with new parts, if necessary. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent breakage of the power control cable assemblies due to the inflexible construction of the cable, which could result in loss of engine power and consequent reduced controllability of the airplane.

Final rule

99-03-06 SHORT BROTHERS, PLC: Amendment 39-11020. Docket 98-NM-289-AD.
Applicability: All Model SD3-60 SHERPA series airplanes; 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 as indicated, unless accomplished previously.

To prevent breakage of the power control cable assemblies due to the inflexible construction of the cable, which could result in loss of engine power and consequent reduced controllability of the airplane, accomplish the following:

(a) Within 1,200 flight hours after the effective date of this AD, perform a one-time visual inspection to determine the part number (P/N) of the power control cable assemblies and pulleys of the engine controls, in accordance with Part A of the Accomplishment Instructions of Shorts Service Bulletin SD3-60 SHERPA-76-1, dated July 1998, or Revision 1, dated October 14, 1998.

(1) If any power control cable assembly having P/N SD3-47-1091 or SD3-47-1094 is found, prior to further flight, replace the power control cable assembly with a new power control cable assembly in accordance with Part B of the Accomplishment Instructions of the service bulletin.

(2) If any pulley having P/N C181605 is found, prior to further flight, replace the pulley with a new pulley in accordance with Part C of the Accomplishment Instructions of the service bulletin.

(b) As of the effective date of this AD, no person shall install on the engine controls of any airplane a cable assembly having P/N SD3-47-1091 or SD3-47-1094, or any pulley having P/N C181605.

(c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Manager, International Branch, ANM-116.

(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) The inspection and replacement shall be done in accordance with Shorts Service Bulletin SD3-60 SHERPA-76-1, dated July 1998, or with Shorts Service Bulletin SD3-60 SHERPA-76-1, Revision 1, dated October 14, 1998, which contains the following list of effective pages:

Page Number
Revision Level
Shown on Page
Date Shown on
Page
1-3, 7, 8, 10-16, 23, 29
1
July 1998
4-6, 9, 17-22, 24-28
Original
October 14, 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 Short Brothers, Airworthiness & Engineering Quality, P.O. Box 241, Airport Road, Belfast BT3 9DZ, Northern Ireland. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; 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 British airworthiness directive 004-07-98.

(f) This amendment becomes effective on March 11, 1999.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to all Short Brothers Model SD3-60 SHERPA series airplanes was published in the Federal Register on November 30, 1998 (63 FR 65718). That action proposed to require a one-time visual inspection to determine the part number of the power control cable assemblies and pulleys of the engine controls; and replacement of the power control cable assemblies and pulleys (as applicable) with new parts, if necessary.

Comments
Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were submitted in response to the proposal or the FAA's determination of the cost to the public.

Additional Service Information
Since the issuance of the proposal, Short Brothers has issued Service Bulletin SD3-60 SHERPA-76-1, Revision 1, dated October 14, 1998. The FAA has determined that the technical procedures described in that revision are equivalent to the technical procedures described in SD3-60 SHERPA-76-1, dated July 1998 (which was cited in the proposal as the appropriate source of service information for accomplishment of the actions). The only change effected by Revision 1 is to clarify certain procedures. The final rule has been revised to require accomplishment of the actions in accordance with either the original issue or Revision 1 of the service bulletin.

Conclusion
The FAA has determined that air safety and the public interest require the adoption of the rule with the change previously described. The FAA has determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD.

Cost Impact
The FAA estimates that 28 airplanes of U.S. registry will be affected by this AD, that it will take approximately 15 work hours per airplane to accomplish the required inspection, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $25,200, or $900 per airplane.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.

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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from 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 the following new airworthiness directive: