Airworthiness Directives; Bombardier Model CL-600-1A11 (CL-600) and CL-600-2A12 (CL-601) 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 CL-600-1A11 (CL-600) and CL-600-2A12 (CL-601) series airplanes. This proposal would require modification of the main landing gear (MLG) brake units and inboard MLG wheels; and a revision to the Airplane Flight Manual (AFM) to include the increased cooling times for the modified brakes. This proposal also would allow, for certain cases, removal of the inboard and/or outboard wheel discs by installation of a placard to limit airplane operation on the ground and a revision to the AFM to include information for operating the airplane with the wheel discs removed. 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 water freezing on the brake while the airplane is in flight due to water, slush, or snow from the runway entering into the brake assemblies during takeoff, and consequently, a tire burst during landing of the airplane.

DATES:

Comments must be received by May 1, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-26-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays.

The service information referenced in the proposed rule may be obtained from Bombardier, Inc., Canadair, Aerospace Group, P.O. Box 6087, Station Centre-ville, Montreal, Quebec H3C 3G9, 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:

James E. Delisio, Aerospace Engineer, Airframe and Propulsion Branch, ANE-171, FAA, Engine and Propeller Directorate, New York Aircraft Certification Office, 10 Fifth Street, Third Floor, Valley Stream, New York 11581; telephone (516) 256-7521; 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 filed in 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 99-NM-26-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. 99-NM-26-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

Transport Canada Civil Aviation (TCCA), which is the airworthiness authority for Canada, notified the FAA that an unsafe condition may exist on certain Bombardier Model CL-600-1A11 (CL-600) and CL-600-2A12 (CL-601) series airplanes. TCCA advises that a tire burst occurred on a number of airplanes during landing. Investigation revealed that the existing design of the main landing gear (MLG) allows water, slush, or snow from the runway to enter into the brake assemblies during takeoff. This condition, if not corrected, could result in the water freezing on the brake while the airplane is in flight, and consequently, a tire burst during landing of the airplane.

Explanation of Relevant Service Information

Bombardier has issued Canadair Challenger Service Bulletins 600-0369, Revision 4, dated June 27, 1984, including Attachment 1, dated December 6, 1983, and Attachment 2, dated January 11, 1984 [for Model CL-600-1A11 (CL-600) series airplanes]; and 601-0024, Revision 3, dated November 27, 1984, including Attachment 1, dated June 21, 1984, Attachment 2, dated December 6, 1983, and Attachment 3, dated January 11, 1984 [for Model CL-600-2A12 (CL-601) series airplanes]. These service bulletins describe procedures for modification of the MLG brake units and inboard MLG wheels; and a revision to the Normal and Limitation Sections of the Airplane Flight Manual (AFM) to include the increased cooling times for the brakes. The modification involves installation of a wheel disc on each inboard MLG wheel; replacement of screws securing the wheel disc on each outboard MLG wheel with longer screws; installation of a water barrier shield and water deflector to each MLG brake unit assembly; removal of balance weights, if fitted, from the main wheel assemblies; and reidentification of brake unit and main wheel assemblies. For certain airplanes, a sealing cap is also installed on each MLG trailing arm aperture.

Bombardier also has issued Canadair Challenger Service Bulletins 600-0662, dated November 30, 1995 [for Model CL-600-1A11 (CL-600) series airplanes]; and 601-0467, dated November 30, 1995 [for Model CL-600-2A12 (CL-601) series airplanes]. These service bulletins describe procedures for removal of the inboard and/or outboard wheel discs by installation of a placard to limit airplane operation on the ground and a revision to the Normal Procedures Section of the AFM to include information for operating the airplane with the wheel discs removed.

Accomplishment of the actions specified in the service bulletins is intended to adequately address the identified unsafe condition. TCCA classified these service bulletins as mandatory and issued Canadian airworthiness directive CF-84-04R2, dated July 24, 1998, in order to assure the continued airworthiness of these airplanes in Canada.

FAA's Conclusions

These airplane models are manufactured in Canada and are type certificated for operation in the United States under the provisions of § 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, TCCA has kept the FAA informed of the situation described above. The FAA has examined the findings of TCCA, 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 131 airplanes of U.S. registry would be affected by this proposed AD.

It would take approximately 33 work hours [for Model CL-600-1A11 (CL-600) series airplanes] or 26 work hours [for Model CL-600-2A12 (CL-601) series airplanes] per airplane to accomplish the proposed modification, at an average labor rate of $60 per work hour. Required parts would cost approximately $2,977 per airplane. Based on these figures, the cost impact of this action proposed by this AD on U.S. operators is estimated to be $649,367 or $4,957 per airplane [for Model CL-600-1A11 (CL-600) series airplanes], and $594,347 or $4,537 per airplane [for Model CL-600-2A12 (CL-601) series airplanes].

It would take approximately 1 work hour per airplane to accomplish the proposed AFM revision, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the AFM revision proposed by this AD on U.S. operators is estimated to be $7,860, or $60 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.

Should an operator elect to accomplish the optional placard installation and AFM revision, it would take approximately 5 work hours per airplane to accomplish these actions, at an average labor rate of $60 per work hour. Required parts would cost approximately $75 per airplane. Based on these figures, the cost impact of these actions is estimated to be $375 per airplane, per modification cycle.

Regulatory Impact

The regulations proposed herein would 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 proposal would not have federalism implications under Executive Order 13132.

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.