Airworthiness Directives; Bombardier Model CL-215-6B11 (CL215T Variant), and CL-215-6B11 (CL415 Variant) Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Bombardier Model CL-215-6B11 series airplanes, that currently requires inspections to detect cracking in the rear engine mount struts, and replacement of struts with new struts, if necessary; and the eventual replacement of all struts with new struts. This action would require adding repetitive detailed inspections to detect cracking in the rear engine mount struts and replacement of struts with new struts, if necessary. This action would also expand the applicability of the existing AD and make the replacement of all struts with new, machined struts an optional terminating action for the repetitive inspections. The actions specified by the proposed AD are intended to prevent failure of the rear engine mount struts, which could subsequently result in reduced structural integrity of the nacelle and engine support structure. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by March 15, 2004.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2003-NM-199-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. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2003-NM-199-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

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, New York Aircraft Certification Office, 1600 Stewart Avenue, Westbury, New York.

FOR FURTHER INFORMATION CONTACT:

David Lawson, Aerospace Engineer, Airframe and Propulsion Branch, ANE-171, FAA, New York Aircraft Certification Office, 1600 Stewart Avenue, Westbury, New York 11590; telephone (516) 228-7327; fax (516) 794-5531.

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 action may be changed in light of the comments received.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

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 action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2003-NM-199-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. 2003-NM-199-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On February 4, 1994, the FAA issued AD 94-04-02, amendment 39-8820 (59 FR 10272, March 4, 1994), applicable to certain Bombardier Model CL-215-6B11 series airplanes, to require inspections to detect cracking in the rear engine mount struts, and replacement of struts with new struts, if necessary; and the eventual replacement of all struts with new struts. That action was prompted by reports of failures of these rear engine mount struts due to cracking that was caused by rosette welds on the shank of the struts not achieving full weld penetration during manufacture. The requirements of that AD are intended to prevent failure of the rear engine mount struts, which could subsequently result in reduced structural integrity of the nacelle and engine support structure.

Actions Since Issuance of Previous Rule

Since the issuance of AD 94-04-02, Transport Canada Civil Aviation (TCCA), which is the airworthiness authority for Canada, has received reports that welded struts installed as terminating action for that AD (reference Canadian airworthiness directive CF-92-22, dated November 17, 1992) have failed in service. Weakness in the welded struts can result in cracks in the rear engine mount struts. This condition, if not corrected, could reduce structural integrity of the nacelle and engine support structure.

Explanation of Relevant Service Information

Bombardier has issued Alert Service Bulletin 215-A3111, Revision 2, dated January 23, 2003 (for Model CL-215-6B11 (CL215T Variant) series airplanes); and Alert Service Bulletin 215-A4287, Revision 2, dated January 23, 2003 (for Model CL-215-6B11 (CL415 Variant) series airplanes). The service bulletins describe repetitive detailed inspections to detect cracking in the rear mount strut assemblies of the engines, and replacement of struts with new, machined or welded struts, if necessary. Replacement of all struts with new, machined struts would eliminate the need for the repetitive inspections. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition. TCCA classified these service bulletins as mandatory and issued Canadian airworthiness directive CF-2003-02, dated February 28, 2003, 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 supersede AD 94-04-02 to continue to require inspections to detect cracking in the rear engine mount struts, and replacement of struts with new struts, if necessary. This new action proposes adding repetitive detailed inspections for new, welded struts, expanding the applicability of the existing AD, and making replacement of all struts with new, machined struts an optional terminating action for the repetitive inspections (replacement of struts with new, welded struts is no longer an optional terminating action). The actions would be required to be accomplished in accordance with the service bulletins described previously, except as described below.

Difference Between Service Bulletins and Proposed AD

Although the service bulletins specify to submit certain information to the manufacturer, this proposed AD does not include such a requirement.

Change Made to Inspection Terminology

The inspection for cracks in AD 94-04-02 is called a “visual inspection.” However, the inspection for cracks in the proposed AD is called a “detailed inspection” and the definition of “detailed inspection” is added to clarify the inspection type.

Optional Terminating Replacement

Operators should also note that, to be consistent with the findings of the TCCA, the FAA has determined that the repetitive inspections proposed by this AD can be allowed to continue in lieu of accomplishment of a terminating action. In making this determination, the FAA considers that, in this case, long-term continued operational safety will be adequately assured by accomplishing the repetitive inspections to detect cracks before it represents a hazard to the airplane.

Cost Impact

There are approximately 3 airplanes of U.S. registry that would be affected by this proposed AD.

The actions that are currently required by AD 94-04-02 take approximately 10 work hours per airplane to accomplish, at an average labor rate of $65 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 currently required actions on U.S. operators is estimated to be $1,950, or $650 per airplane.

The new inspections that are proposed in this AD action take approximately 3 work hours per airplane to accomplish, at an average labor rate of $65 per work hour. Based on these figures, the cost impact of the proposed inspections of this AD on U.S. operators is estimated to be $585, or $195 per airplane, per inspection cycle.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the current or proposed 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.

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.