AD 99-21-27

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Bombardier Model DHC-8-311 and -315 series airplanes, that currently requires replacement of the nitrogen cylinder assemblies that inflate the airplane s ditching dams with improved nitrogen cylinder assemblies. This amendment expands the applicability of the existing AD. 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 ditching dams to inflate fully during an emergency water landing, which could result in water entering the airplane.

Final Rule

99-21-27 BOMBARDIER, INC. (Formerly de Havilland, Inc.): Amendment 39-11373. Docket 98-NM-324-AD. Supersedes AD 98-11-25, Amendment 39-10550.

Applicability: Model DHC-8-311 and -315 series airplanes in the medium and high gross weight configuration, on which Bombardier Change Request CR803SO00001, CR803SO00001-1, CR803SO00002, CR803SO00002-1, CR803CH00046, CR803CH00079, CR803CH00105, CR825CH00847, or CR803CH00051 has been incorporated; certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise 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 (e) 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 ditching dams to inflate fully during an emergency water landing, which could result in water entering the airplane, accomplish the following:

RESTATEMENT OF THE REQUIREMENTS OF AD 98-11-25, AMENDMENT 39-10550:

(a) For airplanes in the medium and high gross weight configuration, on which Bombardier Change Request CR803SO00001, CR803SO00002, CR803CH00046, CR803CH00079, CR803CH00105, CR825CH00847, or CR803CH00051 has been incorporated: Within 6 months after July 8, 1998 (the effective date of AD 98-11-25), replace the existing nitrogen cylinder assembly on the ditching dams with a new nitrogen cylinder assembly that incorporates an improved valve assembly(reference de Havilland Modification 8/3154), in accordance with de Havilland Service Bulletin S.B. 8-25-122, dated October 10, 1997.

(b) For airplanes in the medium and high gross weight configuration, on which Bombardier Change Request CR803SO00001, CR803SO00002, CR803CH00046, CR803CH00079, CR803CH00105, CR825CH00847, or CR803CH00051 has been incorporated: As of July 8, 1998, no person shall install on any airplane any nitrogen cylinder assembly having part number (P/N) 410870(BSC) or 410870-1.

NEW REQUIREMENTS OF THIS AD:

Replacement

(c) For airplanes other than those identified in paragraph (a) of this AD: Within 6 months after the effective date of this AD, replace the existing nitrogen cylinder assembly on the ditching dams with a new nitrogen cylinder assembly having P/N 410870-3 or -5, that incorporates an improved valve assembly (reference de Havilland Modification 8/3154), in accordance with de Havilland Service Bulletin S.B. 8-25-122, dated October 10, 1997.Spares

(d) For airplanes other than those identified in paragraph (a) of this AD: As of the effective date of this AD, no person shall install on any airplane any nitrogen cylinder assembly having P/N 410870(BSC) or 410870-1.

Alternative Methods of Compliance

(e) 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.

Special Flight Permits

(f) 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

(g) The replacement shall be done in accordance with de Havilland Service Bulletin S.B. 8-25-122, dated October 10, 1997. This incorporation by reference was approved previously by the Director of the Federal Register as of July 8, 1998 (63 FR 30121, June 3, 1998). 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.

NOTE 3: The subject of this AD is addressed in Canadian airworthiness directive CF-97-21R1, dated July 22, 1998.

(h) This amendment becomes effective on November 22, 1999.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 98-11-25, amendment 39-10550 (63 FR 30121, June 3, 1998), which is applicable to certain Bombardier Model DHC-8-311 and -315 series airplanes, was published in the Federal Register on August 12, 1999 (64 FR 43959). The action proposed to supersede AD 98-11-25 to continue to require replacement of the nitrogen cylinder assemblies that inflate the airplane s ditching dams with improved nitrogen cylinder assemblies. That action also proposed to expand the applicability of the existing AD.

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

Thereare approximately 2 airplanes of U.S. registry that will be affected by this AD.

The replacement that is currently required by AD 98-11-25, and retained in this AD, will take approximately 4 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will be provided by the manufacturer of the nitrogen cylinder assembly at no cost to the operator. Based on these figures, the cost impact of the replacement currently required on U.S. operators is estimated to be $480, or $240 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 removing amendment 39-10550 (63 FR 30121, June 3, 1998), and by adding a new airworthiness directive (AD), amendment 39-11373, to read as follows: