AD 99-26-11

This amendment adopts a new airworthiness directive (AD), applicable to certain Bombardier Model DHC-7 series airplanes, that requires a one-time visual inspection to detect corrosion on the upper half of the lower longerons on the inboard nacelles; and corrective actions, if necessary. This AD also requires modification of the upper and lower longeron halves. 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 detect and correct corrosion in the upper halves of the left and right hand lower longerons on the inboard nacelles, which could result in a landing gear failure.

Final Rule

99-26-11 BOMBARDIER, INC. (Formerly de Havilland, Inc.): Amendment 39-11470. Docket 99-NM-165-AD.

Applicability: Model DHC-7 series airplanes, serial numbers 004 through 113 inclusive, except serial numbers 037 and 061, 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, unless accomplished previously.

To detect and correct corrosion in the upper halves of the left and right hand lower longerons on the inboard nacelles, which could result in a landing gear failure, accomplish the following:

Inspection

(a) Within 6 months after the effective date of this AD, perform a visual inspection to detect corrosion on the upper half of the lower longerons on the inboard nacelles in accordance with Bombardier Service Bulletin S.B. 7-54-19, Revision `C,' dated April 16, 1999.
Modification

(b) If no corrosion is detected, prior to further flight, modify the upper and lower longeron halves in accordance with Bombardier Service Bulletin S.B. 7-54-19, Revision `C,' dated April 16, 1999.

Corrective Action

(c) If any corrosion is detected, prior to further flight, accomplish the actions specified in paragraph (c)(1) or (c)(2) of this AD, as applicable, in accordance with Bombardier Service Bulletin S.B. 7-54-19, Revision `C,' dated April 16, 1999.

(1) For corrosion that is within the limits specified in the service bulletin: Accomplish the corrective actions specified in the service bulletin, and perform a fluorescent penetrant inspection or high frequency eddy current inspection to detect cracks in areas where corrosion was blended out. The corrective actions and inspections shall be done in accordance with the service bulletin.

(i) If no crack is detected, prior to further flight, modify the upper and lower longeron halves in accordance with the service bulletin.

(ii) If any crack is detected, prior to further flight, accomplish the actions required by paragraphs (c)(1)(ii)(A) and (c)(1)(ii)(B) of this AD.

(A) Either replace the longeron with a new longeron in accordance with the service bulletin, or repair in accordance with a method approved by either the Manager, New York Aircraft Certification Office (ACO), FAA, Engine and Propeller Directorate; or Transport Canada Civil Aviation (or it's delegated agent). For a repair method to be approved by the Manager, New York ACO, as required by this paragraph, the Manager's approval letter must specifically reference this AD.

(B) Modify the upper and lower longeron halves in accordance with the service bulletin.

(2) For corrosion that exceeds the limits specified in the service bulletin: Accomplish the actions required in paragraphs (c)(1)(ii)(A) and (c)(1)(ii)(B) of this AD.

Alternative Methods of Compliance

(d) 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 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.

Special Flight Permits

(e) 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.

Incorporation by Reference

(f) Except at provided by paragraph (c)(1)(ii)(A) of this AD, the actions shall be done in accordance with Bombardier Service Bulletin S.B. 7-54-19, Revision `C,' dated April 16, 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 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 AircraftCertification 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.

NOTE 3: The subject of this AD is addressed in Canadian airworthiness directive CF- 99-07, dated March 15, 1999.

(g) This amendment becomes effective on January 24, 2000.

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 Bombardier Model DHC-7 series airplanes was published in the Federal Register on October 14, 1999 (64 FR 55640). That action proposed to require a one time visual inspection to detect corrosion on the upper half of the lower longerons on the inboard nacelles; and corrective actions, if necessary. That action also proposed to require modification of the upper and lower longeron halves.

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

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 32 airplanes of U.S. registry will be affected by this AD.
It will take approximately 8 work hours per airplane to accomplish the required inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the inspection required by this AD on U.S. operators is estimated to be $15,360, or $480 per airplane.

It will take approximately 12 work hours per airplane to accomplish the required modification, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the modification required by this AD on U.S. operators is estimated to be $23,040, or $720 per airplane.

The cost impact figures discussed above are 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 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: