AD 99-03-07

This amendment adopts a new airworthiness directive (AD), applicable to all Bombardier Model DHC-7 series airplanes, that requires removal of all attachment bolts and pre-load indicating (PLI) washers of the wing-to-fuselage attachment fittings; a one-time visual inspection to detect corrosion of each attachment bolt; and installation of new attachment bolts and PLI washers of the wing-to-fuselage attachment fittings. 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 failure of the attachment bolts of the wing-to-fuselage attachment fittings due to stress corrosion cracking, which could result in reduced structural integrity of the airplane.

Final rule

99-03-07 BOMBARDIER, INC. (Formerly de Havilland, Inc.): Amendment 39-11021. Docket 98-NM-295-AD.
Applicability: All Model DHC-7 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 (b) 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 failure of the attachment bolts of the wing-to-fuselage attachment fittings due to stress corrosion cracking, which could result in reduced structural integrity of the airplane, accomplish the following:

(a) Within 12 months after the effective date of this AD, accomplish the requirements of paragraphs (a)(1), (a)(2), and (a)(3) of this AD, in accordance with Bombardier Service Bulletin S.B. 7-57-37, dated August 8, 1997.

(1) Remove all attachment bolts (one at a time) and pre-load indicating (PLI) washers of the wing-to-fuselage attachment fittings.

(2) Perform a one-time visual inspection to detect corrosion of each attachment bolt. If any corrosion is detected, within 10 days after accomplishing the visual inspection, or within 10 days after the effective date of this AD, whichever occurs later, submit a report of the inspection results to Bombardier, Inc., Bombardier Regional Aircraft Division, Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056.

(3) Install new attachment bolts (one at a time) and new PLI washers of the wing-to-fuselage attachment fittings.

(b) 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, New York Aircraft Certification Office (ACO), FAA, Engine and Propeller Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, New York ACO.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the New York ACO.

(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) The removal, inspection, and installation shall be done in accordance with Bombardier Service Bulletin S.B. 7-57-37, dated August 8, 1997. 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 Bombardier, Inc., Bombardier Regional Aircraft Division, Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA Engine and Propeller Directorate, New York Aircraft Certification Office, 10 Fifth Street, Third Floor, Valley Stream, New York; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

NOTE3: The subject of this AD is addressed in Canadian airworthiness directive CF-98-12, dated June 24, 1998.

(e) 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 Bombardier Model DHC-7 series airplanes was published in the Federal Register on November 30, 1998 (63 FR 65716). That action proposed to require removal of all attachment bolts and pre-load indicating (PLI) washers of the wing-to-fuselage attachment fittings; a one-time visual inspection to detect corrosion of each attachment bolt; and installation of new attachment bolts and PLI washers of the wing-to-fuselage attachment fittings.

Conclusion
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. 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 50Model DHC-7 series airplanes of U.S. registry will be affected by this AD, that it will take approximately 65 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $3,200 per airplane. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $355,000, or $7,100 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 thatthis 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: