AD 99-19-34

This amendment adopts a new airworthiness directive (AD), applicable to certain Bombardier Model DHC-8-100 and -300 series airplanes, that requires modification of certain hydraulic systems that provide hydraulic pressure for the control of the rudder and for the main landing gear brakes. 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 damage to certain hydraulic system components in the number 2 engine nacelle, which could result in loss of the number 1 and number 2 hydraulic systems, and consequent reduced controllability of the airplane.

Final Rule

99-19-34 BOMBARDIER, INC. (Formerly de Havilland, Inc.): Amendment 39-11321. Docket 97-NM-58-AD.

Applicability: Model DHC-8-100 and -300 series airplanes having serial numbers 003 through 405; except those airplanes on which Bombardier Modifications 8/1152 and 8/1982 have been installed, and on which either Bombardier Modification 8/1983 or 8/2781 has been installed; 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 (c) 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 damage to certain hydraulic system components in the number 2 engine nacelle, which could result in loss of the number 1 and number 2 hydraulic systems, and consequent reduced controllability of the airplane, accomplish the following:

(a) Within 18 months after the effective date of this AD, modify certain hydraulic systems that provide hydraulic pressure for the control of the rudder and for the main landing gear brakes by accomplishing the requirements of paragraph (a)(1) or (a)(2), as applicable, in accordance with Bombardier Service Bulletin S.B. 8-32-128, Revision `C,' dated March 27, 1998.

(1) For all airplanes on which Bombardier Modification 8/1152 has been installed: Accomplish Part A of the Accomplishment Instructions of the service bulletin.

(2) For all airplanes on which Bombardier Modification 8/1152 has not been installed: Accomplish Part B of the Accomplishment Instructions of the service bulletin.

(b) Within 18 months after the effective date of this AD, accomplish the actions specified in either paragraph (b)(1) or (b)(2) of this AD.

(1) Relocate the number 2 standby power unit (SPU) of the number 2 hydraulic system in accordance with Bombardier Service Bulletin S.B. 8-29-23, dated December 6, 1996; or

(2) Install a hydraulic rudder isolation system in the number 1 and number 2 hydraulic systems in accordance with Bombardier Service Bulletin S.B. 8-29-29, dated February 27, 1998.

(c) 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.

(d) 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

(e) The actions shall be done in accordance with Bombardier Service Bulletin S.B. 8-32-128, Revision `C,' dated March 27, 1998; Bombardier Service Bulletin S.B. 8-29-23, dated December 6, 1996; or Bombardier Service Bulletin S.B. 8-29-29, dated February 27, 1998; 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 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 directives CF-96-25R1, dated January 16, 1997, and CF-96-25R2, dated September 10, 1998.

(f) This amendment becomes effective on October 27, 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 certain Bombardier Model DHC-8-100 and -300 series airplanes was published in the Federal Register on July 7, 1999 (64 FR 36624). That action proposed to require modification of certain hydraulic systems that provide hydraulic pressure for the control of the rudder and for the main landing gear brakes.

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 148 airplanes of U.S. registry will be affected by this AD.

For airplanes identified in Bombardier Service Bulletin S.B.8-32-128, Revision C, it will take between 15 and 40 work hours per airplane to accomplish the required modification, at an average labor rate of $60 per work hour. Required parts will be provided by the manufacturer at no cost to the operators. Based on these figures, the cost impact of the modification required by this AD on U.S. operators is estimated to be between $133,200 and $355,200, or between $900 and $2,400 per airplane.

For airplanes identified in Bombardier Service Bulletin S.B. 8-29-23, it will take approximately 346 work hours per airplane to accomplish the required relocation, at an average labor rate of $60 per work hour. Required parts will be provided by the manufacturer at no cost to the operators. Based on these figures, the cost impact of the modification required by this AD on U.S. operators is estimated to be $3,072,480, or $20,760 per airplane.

For airplanes identified in Bombardier Service Bulletin S.B. 8-29-29, it will take approximately 120 work hours per airplane to accomplish the required installation, at an average labor rate of $60 per work hour. Required parts will be provided by the manufacturer at no cost to the operators. Based on these figures, the cost impact of the installation required by this AD on U.S. operators is estimated to be $1,065,600, or $7,200 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 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 adding the following new airworthiness directive: