AD 2004-13-04

This amendment adopts a new airworthiness directive (AD), applicable to certain Short Brothers Model SD3-SHERPA series airplanes, that requires a repetitive detailed inspection of the stub wing shear decks for corrosion and abnormal wear on and around the retaining pin in the main landing gear (MLG) forward pintle pin; and corrective action, if necessary. This AD also provides an optional terminating action. These actions are necessary to detect and correct corrosion and abnormal wear to the top and bottom shear decks, which could result in damage to the MLG and consequent reduced controllability of the airplane on landing. This action is intended to address the identified unsafe condition.

Final rule.

2004-13-04 Short Brothers PLC: Amendment 39-13685. Docket 2003-NM-235-AD.

Applicability: Model SD3-SHERPA series airplanes, except those that have embodied Short Brothers Service Bulletin SD3 SHERPA-32-4, dated July 2003; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To detect and correct corrosion and abnormal wear to the top and bottom shear decks, which could result in damage to the main landing gear (MLG) and consequent reduced controllability of the airplane on landing, accomplish the following:

Repetitive Inspections

(a) Within 6 months after the effective date of this AD, and continuing at intervals not to exceed 6 months, perform a detailed inspection of the stub wing shear decks to detect corrosion and/or abnormal wear according to the Accomplishment Instructions of Short Brothers Service Bulletin SD3 SHERPA-53-6, dated May 2003.

Note 1: For the purposes of this AD, a detailed inspection is defined as: "An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required."

Repair

(b) If any corrosion and/or abnormal wear is discovered during the inspection required by paragraph (a) of this AD, before further flight, perform corrective actions in accordance with the Accomplishment Instructions of Short Brothers Service Bulletin SD3 SHERPA-53-6, dated May 2003, Part B and/or Part C as applicable; except where the service bulletin specifies that operators should contact the manufacturer for disposition of certain repair conditions, before further flight, repair those conditions per a method approved by the Manager, International Branch, ANM-116, Transport Airplane Directorate, FAA; or the UK-CAA (or its delegated agent).

Optional Terminating Action

(c) Performance of the optional terminating action, which includes replacement of the retaining pin and circlip with a new retaining pin, washer, castellated nut, and cotter pin, per the Accomplishment Instructions of Short Brothers Service Bulletin SD3 SHERPA-32-4, dated July 2003, terminates the requirement for repetitive detailed inspections specified in paragraph (a) of this AD.

No Reporting Requirement

(d) Operators should note that, although Short Brothers Service Bulletin SD3 SHERPA-32-4, dated May 2003, describes procedures for reporting inspection results to the manufacturer, this AD does not require that action.

Alternative Methods of Compliance

(e) In accordance with 14 CFR 39.19, the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, is authorized to approve alternative methods of compliance for this AD.

Incorporation by Reference

(f) Unless otherwise specified in this AD, the actions shall be done in accordance with Short Brothers Service Bulletin SD3 SHERPA-53-6, dated May 2003; and Short Brothers Service Bulletin SD3 SHERPA-32-4, dated July 2003; as applicable. 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 Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call (202) 741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

Note 2: The subject of this AD is addressed in British airworthiness directive 004-05-2003, dated August 2003.

Effective Date

(g) This amendment becomes effective on July 29, 2004.

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 certain Short Brothers Model SD3-SHERPA series airplanes was published in the Federal Register on April 15, 2004 (69 FR 19956). That action proposed to require a repetitive detailed inspection of the stub wing shear decks for corrosion and abnormal wear on and around the retaining pin in the main landing gear (MLG) forward pintle pin; and corrective action, if necessary. That action also proposed an optional terminating action.

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.

Conclusion

After careful review of the available data, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

Cost Impact

The FAA estimates that 16 airplanes of U.S. registry will be affected by this AD, that it will take approximately 13 work hours per airplane to accomplish the required actions, and that the average labor rate is $65 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $13,520, or $845 per airplane, per inspection.

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. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

If an operator chooses to accomplish the optional terminating action rather than continue the repetitive detailed inspections, it will take about 12 work hours per stub wing (2 stub wings per airplane) to accomplish the replacement of the retaining pin and circlip with a new retaining pin with castellated nut and cotter pin, at an average labor rate of $65 per work hour. Required parts will cost about $2,400 per stub wing. Based on these figures, we estimate the cost of this optional terminating action to be $6,360 per airplane.

Regulatory Impact

The regulations adopted herein will not have a substantial direct effect 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, it is determined that this final rule does not have federalism implications under Executive Order 13132.

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: