AD 2003-25-05

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Bombardier DHC-8-102, -103, -106, -201, - 202, -301, -311, and -315 airplanes, that currently requires inspections to detect breakage in the struts of the rear mount strut assemblies on the left and right engine nacelles, and replacement of any broken struts. The existing AD also requires eventual replacement of all currently installed struts with new and/or reworked struts, as terminating action for the inspections. The amendment requires new repetitive inspections of the strut assemblies for cracking of struts replaced per the existing AD, and replacement of any cracked strut with a new, machined strut. The amendment also changes the applicability of the existing AD by adding certain airplanes and removing certain other airplanes, and includes an optional terminating action for the repetitive inspections. The actions specified by this AD are intended to prevent failure of the engine rear mount struts, which could result in reduced structural integrity of the nacelle and engine support structure. This action is intended to address the identified unsafe conditions.

Final rule.

2003-25-05 Bombardier, Inc. (Formerly de Havilland, Inc.): Amendment 39-13388. Docket 2001-NM-266-AD. Supersedes AD 94-04-09, Amendment 39-8829.

Applicability: Model DHC-8-102, -103, -106, -201, -202, -301, - 311, and -315 airplanes; serial numbers 003 through 509 inclusive; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of the engine rear mount struts on the left and right engine nacelles, which could result in reduced structural integrity of the nacelle and engine support structure, accomplish the following:

Repetitive Inspections

(a) Within 1,000 flight hours since installation of any new or reworked rear mount strut per the replacement required by paragraph (b) of AD 94-04-09, amendment 39-8829, or within 250 flight hours after the effective date of this AD, whichever is later; do a detailed inspection for cracking of each rear mount strut in the left and right engine nacelles.

Note1: Bombardier Service Bulletin 8-71-24, dated August 21, 2001, does not contain inspection procedures for the detailed inspection required by paragraph (a) of this AD; however, the definition of a detailed inspection is specified in Note 2 of this AD.

Note 2: 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."

(1) If no crack is found, repeat the inspection at intervals not to exceed 250 flight hours, until accomplishment of paragraph (b) of this AD.

(2) If any crack is found, before further flight, replace the strut with a new, improved strut per Bombardier Service Bulletin 8- 71-24, dated August 21, 2001. Repeat the inspection thereafter at intervals not to exceed 500 flight hours, for that nacelle only.

Optional Terminating Action

(b) Replacement of both rear mount struts in a nacelle with new, improved struts, by doing all the actions specified in the Job Set- up, Procedure, and Close-out sections of the Accomplishment Instructions of Bombardier Service Bulletin 8-71-24, dated August 21, 2001, ends the repetitive inspections required by this AD for that nacelle only. Replacement of both rear mount struts on both the left and right engine nacelles ends the repetitive inspections required by this AD.

Parts Installation

(c) As of the effective date of this AD, no person shall install an engine rear mount strut, P/N 87110016-001, -003, -005, -007, - 009, or -011, on any airplane.

Alternative Methods of Compliance

In accordance with 14 CFR 39.19, the Manager, New York Aircraft Certification Office, FAA, isauthorized to approve alternative methods of compliance for this AD.

Incorporation by Reference

(e) Unless otherwise provided in this AD, the actions shall be done in accordance with Bombardier Service Bulletin 8-71-24, dated August 21, 2001. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 522(a) and 1 CFR part 51. Copies may be obtained from Bombardier, Inc., Bombardier Regional Aircraft Division, 123 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, 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.

Note 3: The subject of this AD is addressed in Canadian airworthiness directive CF-2001-20, dated May 16, 2001.

Effective Date

(f)This amendment becomes effective on January 22, 2004.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 94-04-09, amendment 39-8829 (59 FR 8393, February 22, 1994), which is applicable to certain Bombardier Model DHC-8-100 and DHC-8-300 airplanes, was published in the Federal Register on October 9, 2003 (68 FR 58283). The action proposed to require new repetitive inspections of the strut assemblies for cracking of struts replaced per the existing AD, and replacement of any cracked strut with a new, machined strut. The action also proposed to change the applicability of the existing AD by adding certain airplanes and removing certain other airplanes, and proposed to include an optional terminating action for the repetitive inspections.

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

There are approximately 192 airplanes of U.S. registry that will be affected by this AD.

The actions that are currently required by AD 94-04-09 take approximately 16 work hours per airplane to accomplish, at an average labor rate of $65 per work hour. Required parts are provided by the manufacturer at no cost to the operators. Based on these figures, the cost impact of the currently required actions is estimated to be $1,040 per airplane.

The new detailed inspection that is required in this AD action takes approximately 1 work hour per airplane to accomplish, at an average labor rate of $65 per work hour. Based on these figures, the cost impact of the required inspection on U.S. operators is estimated to be $12,480, or $65 per airplane, per inspection cycle.

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. 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.

The optional terminating action, if done, will take approximately 16 work hours per strut to accomplish, at an average labor rate of $65 per work hour. Required parts will cost aproxiamately $800 per strut. Based on these figures, the cost impact of the optional terminating action is estimated to be $1,840 per strut, 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 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of theAmendment

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 removing amendment 39-8829 (59 FR 8393, February 22, 1994), and by adding a new airworthiness directive (AD), amendment 39-13388, to read as follows: