Airworthiness directives: Bombardier,

[Federal Register: July 7, 1999 (Volume 64, Number 129)]

[Proposed Rules]

[Page 36624-36626]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr07jy99-30]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-58-AD]

RIN 2120-AA64

Airworthiness Directives; Bombardier Model DHC-8-100 and -300 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Bombardier Model DHC-8-100 and -300 series airplanes. This proposal would require modification of certain hydraulic systems that provide hydraulic pressure for the control of the rudder and for the main landing gear brakes. This proposal is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by the proposed 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.

DATES: Comments must be received by August 6, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 97-NM-58-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays.

The service information referenced in the proposed rule may be obtained from Bombardier, Inc., Bombardier Regional Aircraft Division, Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. This information may be examined 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.

FOR FURTHER INFORMATION CONTACT: Anthony Gallo, Aerospace Engineer, Systems and Flight Test Branch, ANE-172, FAA, Engine and Propeller

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Directorate, New York Aircraft Certification Office, 10 Fifth Street, Third Floor, Valley Stream, New York 11581; telephone (516) 256-7510; fax (516) 568-2716.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filedin the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 97-NM-58-AD.'' The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 97-NM-58-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

Transport Canada Aviation (TCA), which is the airworthiness authority for Canada, notified the FAA that an unsafe condition may exist on certain Bombardier Model DHC-8-100 and -300 series airplanes. TCA advises that it has received reports of hydraulic system damage in the number 2 engine nacelle caused by in-flight, fuel-fed engine fires; and in one incident, the complete hull of the airplane was lost. In each incident, the fire was caused by leaking and igniting fuel. However, the source of the fuel leak in each incident was a different source, as was the source of ignition.

Investigation revealed that the hydraulic system did not cause the fire in any of the incidents, however, the damage from the fires resulted in a total loss of hydraulic pressure in both hydraulic systems 1 and 2. These hydraulic systems supply hydraulic power for the control of the rudder and for the main landing gear (MLG) brakes. Further investigation revealed that the location of the number 2 standby power unit (SPU) and certain hydraulic components of the parking brake system (i.e., parking brake accumulator, charging valve, and viewing gauge) may have contributed to the hydraulic system damage. Such damage, if not corrected, could result in loss of the number 1 and number 2 hydraulic systems, and consequent reduced controllability of the airplane.

Explanation of Relevant Service Information

Bombardier has issued the following service bulletins which describe procedures for modification of certain hydraulic systems that provide hydraulic pressure for the control of the rudder and for the main landing gear brakes:

Bombardier Service Bulletin S.B. 8-32-128, Revision `C,' dated March 27, 1998, describes procedures for modification of the parking brake accumulator and charging valve of the parking brake system. This service bulletin is divided into two parts, A and B, respectively.

Part A of the Accomplishment Instructions (Bombardier Modification 8/1982) is applicable to airplanes on which Bombardier Modification 8/ 1152 has been installed. Part A of the Accomplishment Instructions describes procedures for relocation of the parking brake charging valve from the number 2 engine nacelle to the right-hand wing root, modification of the wing root and installation of a new front access panel, support, cleat, and associated hydraulic tubes.

Part B of the Accomplishment Instructions (Bombardier Modifications 8/1152 and 8/1982) is applicable to airplanes on which Bombardier Modification 8/1152 has not been installed. Part B of the Accomplishment Instructions describes procedures for relocation of the parking brake accumulator, charging valve, and viewing gauge; and installation of a new support assembly, panel assembly, viewing port, and tube assemblies in the right-hand wing root.

Bombardier Service Bulletin S.B. 8-29-23, dated December 6, 1996, describes procedures for relocation of the number 2 SPU of the number 2 engine nacelle to the rear fuselage; and installation of a new support assembly, hydraulic isolation valve, tube assemblies, wiring, circuit breaker, caution indicator, and associated relays.

Bombardier Service Bulletin S.B. 8-29-29, dated February 27, 1998, describes procedures for installation of a hydraulic rudder isolation system that involves installation of two new hydraulic isolation valves, electrical wiring, caution lights, and tube assemblies. Accomplishment of Service Bulletin S.B. 8-29-29 is an alternative to the modification described in Service Bulletin S.B. 8-29-23.

Accomplishment of the actions specified in these service bulletins is intended to adequately address the identified unsafe condition. TCA has approved these service bulletins and issued Canadian airworthiness directives CF-96-25R1, dated January 16, 1997, and CF-96-25R2, dated September 10, 1998, in order to assure the continued airworthiness of these airplanes in Canada.

FAA's Conclusions

This airplane model is manufactured in Canada and is type certificated for operation in the United States under the provisions of Sec. 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, TCA has kept the FAA informed of the situation described above. The FAA has examined the findings of TCA, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, the proposed AD would require accomplishment of the actions specified in the service bulletins described previously.

Cost Impact

The FAA estimates that 148 airplanes of U.S. registry would be affected by this proposed AD.

For airplanes identified in Bombardier Service Bulletin S.B. 8-32- 128, Revision `C,' it would take between 15 and 40 work hours per airplane to accomplish the proposed modification, at an average labor rate of $60 per work hour. Required parts would be provided by the manufacturer at no cost to the

[[Page 36626]]

operators. Based on these figures, the cost impact of the modification proposed 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 would take approximately 346 work hours per airplane to accomplish the proposed relocation, at an average labor rate of $60 per work hour. Required parts would be provided by the manufacturer at no cost to the operators. Based on these figures, the cost impact of the modification proposed 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 would take approximately 120 work hours per airplane to accomplish the proposed installation, at an average labor rate of $60 per work hour. Required parts would be provided by the manufacturer at no cost to the operators. Based on these figures, the cost impact of the installation proposed 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 proposed 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 proposed herein would 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 proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this proposed regulation (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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.

    Sec. 39.13 [Amended]

  2. Section 39.13 is amended by adding the following new airworthiness directive:

    Bombardier, Inc. (Formerly de Havilland, Inc.): 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.

    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.

    Issued in Renton, Washington, on June 30, 1999. D.L. Riggin, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

    [FR Doc. 99-17177Filed7-6-99; 8:45 am]

    BILLING CODE 4910-13-P

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