Airworthiness Directives; Bombardier Model CL-600-1A11 (CL-600), CL-600-2A12 (CL-601), and CL-600-2B16 (CL-601-3A, CL-601-3R, and CL-604) 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 transport category airplanes, that currently requires a detailed inspection to detect cracks of the vane brackets of the inboard flap actuator beam, and follow-on repetitive detailed inspections or corrective actions, as applicable. That AD also provides for two optional terminating actions for the detailed inspection(s). This action would require performing one or the other of the terminating actions. The actions specified by the proposed AD are intended to detect and correct gaps between the flap vane bracket and the adjacent lower skin and between the flap vane bracket and vane actuator beam, and premature cracking of the flap vane brackets, which could result in failure of the flap vane bracket(s) when the flaps are extended and the flap vane is aerodynamically loaded, and consequent reduced controllability of the airplane. 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. 2003-175-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-175-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 Ave., Westbury, New York.

FOR FURTHER INFORMATION CONTACT:

Serge Napoleon, Aerospace Engineer, Airframe and Propulsion Branch, ANE-171, FAA, New York Aircraft Certification Office, 1600 Stewart Avenue, Westbury, New York 11590; telephone (516) 228-7312; 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-175-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-175-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On April 14, 2003, the FAA issued AD 2003-08-12, amendment 39-13125 (68 FR 19940, April 23, 2003), applicable to certain Bombardier Model CL-600-1A11 (CL-600), CL-600-2A12 (CL-601), and CL-600-2B16 (CL-601-3A, CL-601-3R, and CL-604) series airplanes, to require a detailed inspection to detect cracks of the vane brackets of the inboard flap actuator beam, and follow-on repetitive detailed inspections or corrective actions, as applicable. That AD also provides for two optional terminating actions for the detailed inspection(s). That action was prompted by reports of several occurrences of gaps found between the flap vane bracket and the adjacent lower skin and between the flap vane bracket and vane actuator beam. During a detailed investigation, it was found that an incorrect production process for the installation of the vane bracket resulted in an uneven contact with the adjacent skin and with the vane actuator beam. The requirements of that AD are intended to detect and correct gaps between the flap vane bracket and the adjacent lower skin and between the flap vane bracket and vane actuator beam of the wing flap systems, and premature cracking of the flap vane brackets, which could result in failure of the flap vane bracket(s) when the flaps are extended and the flap vane is aerodynamically loaded. Loss or warping of the flap vane in flight could decrease the lift on one side of the airplane, which could lead to reduced controllability of the airplane.

Actions Since Issuance of Previous Rule

When AD 2003-08-12 was issued, it contained a provision for two optional terminating actions for the detailed inspections. In the preamble to AD 2003-08-12, the FAA indicated that the actions required by that AD were considered to be “interim action” and that further rulemaking action was being considered to require performing either one of the two corrective actions, which would constitute terminating action for the detailed inspections. We now have determined that further rulemaking is indeed necessary, and this proposed AD follows from that determination.

Canadian Airworthiness Directives

Transport Canada Civil Aviation (TCCA) classified the alert service bulletins specified in Table 2 of this AD and the Time Limits/Maintenance Checks (TLMC) (all described below) as mandatory and issued Canadian airworthiness directives CF-2002-36 and CF-2002-37, both effective August 30, 2002, in order to assure the continued airworthiness of these airplanes in Canada.

Explanation of Relevant Service Information

Bombardier has issued the alert service bulletins specified in Table 2 of this proposed AD, which describe procedures for a detailed inspection to detect cracks of the vane brackets of the inboard flap actuator beam, and follow-on repetitive detailed inspections or corrective actions (i.e., Part B or Part C), as applicable.

Part B corrective actions include:

• Doing a detailed inspection to detect gaps at flap stations 60.0, 98.5, and 137.0 between the flap vane bracket(s) and adjacent lower skin and between the flap vane bracket and vane actuator beam, and repair if necessary;
• Measuring the minimum edge distance (MED) for the fastener holes in all flap vane brackets and actuator beams, and replacing any out-of-tolerance bracket and/or actuator beam with a certain new bracket and/or actuator beam; and
• Doing a nondestructive test inspection on all vane brackets for cracks, and corrective actions (e.g., remove gaps, ensure that the MED requirements for the replacement brackets meet the allowable values, and replace any cracked vane bracket with a new bracket that meets the MED requirements).

Part C corrective actions include:

• Replacing all 12 vane brackets with new brackets that meet the MED requirements (including removal of any gap between the flap vane brackets and the adjacent lower skin and between the flap vane bracket and actuator beams); and
• Measuring the MED for the fastener holes in all replacement flap vane brackets and actuator beams (including a detailed inspection for gaps); and replacing any out-of-tolerance bracket and/or actuator beam with a certain new bracket and/or actuator beam that meets the MED requirements, and removing any gap, if necessary.

Accomplishment of Part B or Part C corrective actions eliminates the need for the detailed inspection(s) to detect cracks of the vane brackets of the inboard flap actuator beams, described previously. Accomplishment of the actions specified in the service bulletins is intended to adequately address the identified unsafe condition.

Explanation of Relevant Time Limits/Maintenance Checks

After doing either Part B or Part C corrective actions, Canadian airworthiness directives CF-2002-36 and CF-2002-37 require compliance with the applicable TLMC threshold and repeat interval of the Airplane Maintenance Manual (AMM) for the flap vane brackets.

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, the TCCA has kept the FAA informed of the situation described above. The FAA has examined the findings of the 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 2003-08-12 to continue to require a detailed inspection to detect cracks of the vane brackets of the inboard flap actuator beam, and follow-on repetitive detailed inspections or corrective actions, as applicable. This proposed AD also would require performing either one of the two corrective actions, which would constitute terminating action for the detailed inspections. The actions would be required to be accomplished in accordance with the service bulletins described previously, except as discussed below.

Differences Between the Alert Service Bulletins and This Proposed AD

Although the alert service bulletins describe procedures for identifying and returning all cracked vane brackets to Bombardier, neither the Canadian airworthiness directives nor this proposed AD would require such actions.

In addition, although the alert service bulletins specify that the manufacturer may be contacted for disposition of certain repair conditions, this proposed AD would require the repair of those conditions to be accomplished per a method approved by either the FAA, or TCCA (or its delegated agent). In light of the type of repair that is required to address the identified unsafe condition, and in consonance with existing bilateral airworthiness agreements, the FAA has determined that, for this proposed AD, a repair approved by either the FAA or TCCA will be acceptable for compliance with this proposed AD.

Clarification Between This AD and Canadian Airworthiness Directives/Referenced Alert Service Bulletins

Operators should note that, although the parallel Canadian airworthiness directives require compliance with the applicable TLMC threshold and repeat interval of the AMM for the flap vane brackets, this proposed AD first requires a revision of the Airworthiness Limitation section (ALS) of the Instructions for Continued Airworthiness to incorporate those new threshold and repeat inspection intervals. Revising the ALS, rather than requiring individual repetitive inspections, is advantageous for operators because it allows them to record AD compliance status only at the time that they make the revision, rather than after every inspection. It also has the advantage of keeping all airworthiness limitations, whether imposed by original certification or by AD, in one place with the operator's maintenance program, thereby reducing the risk of non-compliance because of oversight or confusion.

Changes to 14 CFR Part 39/Effect on the Proposed AD

On July 10, 2002, the FAA issued a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs the FAA's airworthiness directives system. The regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance (AMOCs). Because we have now included this material in part 39, only the office authorized to approve AMOCs is identified in each individual AD. Therefore, Notes 1 and 4 and paragraphs (i) and (j) of AD 2003-08-12 are not included in this proposed AD.

Change to Labor Rate Estimate

We have reviewed the figures we have used over the past several years to calculate AD costs to operators. To account for various inflationary costs in the airline industry, we find it necessary to increase the labor rate used in these calculations from $60 per work hour to $65 per work hour. The cost impact information, below, reflects this increase in the specified hourly labor rate.

Cost Impact

There are approximately 411 airplanes of U.S. registry that would be affected by this proposed AD.

The detailed inspection that is currently required by AD 2003-08-12, amendment 39-13125, takes approximately 11 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 currently required actions on U.S. operators is estimated to be $293,865, or $715 per airplane, per inspection cycle.

The terminating corrective actions specified in Part B of the Accomplishment Instructions of the applicable alert service bulletin identified in Table 2 of this AD, take approximately 24 work hours per airplane to accomplish the inspections and between 4 and 48 work hours per airplane to accomplish the replacement of the vane bracket(s), at an average labor rate of $65 per work hour. Required parts would cost between $535 and $6,414 for the vane brackets. Based on these figures, the cost impact of the proposed terminating corrective actions on U.S. operators is estimated to be between $967,905 and $4,559,634, or between $2,355 and $11,094 per airplane.

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 optional terminating corrective actions specified in Part C of the Accomplishment Instructions of the applicable alert service bulletin identified in Table 2 of this AD, takes approximately 80 work hours per airplane to accomplish, at an average labor rate of $65 per work hour. Required parts would cost approximately $6,414 for the vane brackets. Based on these figures, the cost impact of the proposed terminating corrective actions on U.S. operators is estimated to be $4,773,354 or between $11,614 per airplane.

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.