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CFR Citation: 14 CFR Part 39

Docket ID: [Docket No. 2003-NM-199-AD]

RIN ID: RIN 2120-AA64

NOTICE: PROPOSED RULES

ACTION: Airworthiness directives:

DOCUMENT ACTION: Notice of proposed rulemaking (NPRM).

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

DATES: Comments must be received by March 15, 2004.

DOCUMENT SUMMARY: This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Bombardier Model CL2156B11 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.

SUMMARY: Bombardier,

SUPPLEMENTAL INFORMATION

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 issuebyissue. 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 FAApublic 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 selfaddressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 2003NM199AD.'' 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, ANM114, Attention: Rules Docket No. 2003NM199AD, 1601 Lind Avenue, SW., Renton, Washington 980554056.

Discussion

On February 4, 1994, the FAA issued AD 940402, amendment 398820 (59 FR 10272, March 4, 1994), applicable to certain Bombardier Model CL2156B11 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
[[Page 7180]]
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 940402, 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 CF9222, 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 215A3111, Revision 2, dated January 23, 2003 (for Model CL2156B11 (CL215T Variant) series airplanes); and Alert Service Bulletin 215A4287, Revision 2, dated January 23, 2003 (for Model CL2156B11 (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 CF200302, 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 Sec. 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 940402 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 940402 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, longterm 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 940402 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. [[Page 7181]]

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 39AIRWORTHINESS 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 removing amendment 398820 (59 FR 10272, March 4, 1994), and by adding a new airworthiness directive (AD), to read as follows:
Bombardier, Inc. (Formerly Canadair): Docket 2003NM199AD.

Supersedes AD 940402, Amendment 398820.

Applicability: Model CL2156B11 (CL215T Variant) series airplanes, serial numbers 1056, 1057, 1061, 1080, 1109, 1113 through 1122 inclusive, 1124, and 1125; and Model CL2156B11 (CL415 Variant) series airplanes, serial numbers 2001 through 2067 inclusive; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of the rear engine mount struts, which could subsequently result in reduced structural integrity of the nacelle and engine support structure, accomplish the following:
Restatement of Requirements of AD 940402
Inspection and Corrective Action
(a) For Model CL2156B11 series airplanes, serial numbers 1057, 1061, 1080, 1113 through 1115 inclusive, 1121, 1122, 1124, and 1125; turboprop versions only: Within 50 hours timeinservice after April 4, 1994 (the effective date of AD 940402, amendment 398820), perform a visual inspection to detect cracking in the rear engine mount struts, part number (P/N) 87110016003, in accordance with Canadair Alert Service Bulletin 215A3040, dated September 2, 1992. (1) If no cracking is detected, repeat the visual inspection thereafter at intervals not to exceed 50 hours timeinservice, until the requirements of paragraph (b) of this AD are accomplished. (2) If any cracking is detected, prior to further flight, replace the engine rear mount strut with a new strut, P/N 87110016 009 or 011, in accordance with the service bulletin.
(b) For Model CL2156B11 series airplanes, serial numbers 1057, 1061, 1080, 1113 through 1115 inclusive, 1121, 1122, 1124, and 1125; turboprop versions only: Within 2 years after April 4, 1994, replace all engine rear mount struts with new struts, P/N 87110016009 or 011, in accordance with Canadair Alert Service Bulletin 215A3040, dated September 2, 1992. Such replacement constitutes terminating action for the inspections required by paragraph (a) of this AD. (c) For Model CL2156B11 series airplanes, serial numbers 1057, 1061, 1080, 1113 through 1115 inclusive, 1121, 1122, 1124, and 1125; turboprop versions only: As of April 4, 1994, no person shall install a rear engine mount strut, P/N 87110016003, on any airplane.
New Requirements of This AD
Inspection and Corrective Action
(d) For all airplanes: Within 50 flight hours after the effective date of this AD, perform a detailed inspection to detect cracking in the rear mount strut assemblies of the engines in accordance with Bombardier Alert Service Bulletin 215A3111, Revision 2, dated January 23, 2003 (Model CL2156B11 (CL215T Variant) series airplanes); or Bombardier Alert Service Bulletin 215A4287, Revision 2, dated January 23, 2003 (Model CL2156B11 (CL415 Variant) series airplanes); as applicable. Accomplishment of this detailed inspection constitutes terminating action for the requirements of paragraph (a) of this AD.

Note 1: For the purposes of this AD, a detailed inspection is defined as: ``An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally
supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.''
(1) If no cracking is detected, repeat the detailed inspection thereafter at intervals not to exceed 250 flight hours until the requirements of paragraph (e) of this AD are accomplished.
(2) If any crack is detected, before further flight, do the replacement in either paragraph (d)(2)(i) or (d)(2)(ii) of this AD in accordance with the applicable service bulletin.
(i) Replace the rear engine mount strut with a new, welded strut, P/N 87110016009 or 011. Repeat the detailed inspection thereafter at intervals not to exceed 250 flight hours until the requirements of paragraph (e) of this AD are accomplished.
(ii) Replace the rear engine mount strut with a new, machined strut, P/N 87110047001. Repeat the detailed inspection thereafter at intervals not to exceed 500 flight hours for the new, machined strut until the requirements of paragraph (e) of this AD are accomplished.
Optional Terminating Replacement
(e) Replace both rear engine mount struts with new, machined struts, P/N 87110047001, in accordance with Bombardier Alert Service Bulletin 215A3111, Revision 2, dated January 23, 2003 (Model CL2156B11 (CL215T Variant) series airplanes); or Bombardier Alert Service Bulletin 215A4287, Revision 2, dated January 23, 2003 (Model CL2156B11 (CL415 Variant) series airplanes); as applicable. Replacement constitutes terminating action for the repetitive inspections required by this AD.
Parts Installation
(f) As of the effective date of this AD, no person shall install a rear engine mount strut, P/N 87110016003, on any airplane. Reporting Paragraph in Service Bulletins
(g) Although the service bulletins referenced in this AD specify to submit certain information to the manufacturer, this AD does not include such a requirement.
Alternative Methods of Compliance
(h) In accordance with 14 CFR 39.19, the Manager, New York Aircraft Certification Office (ACO), FAA, is authorized to approve alternative methods of compliance (AMOCs) for this AD.

Note 2: The subject of this AD is addressed in Canadian airworthiness directive CF200302, dated February 28, 2003.

Issued in Renton, Washington, on February 5, 2004. Kevin M. Mullin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 043206 Filed 21204; 8:45 am]
BILLING CODE 491013P

FOR FURTHER INFORMATION CONTACT David Lawson, Aerospace Engineer, Airframe and Propulsion Branch, ANE171, FAA, New York Aircraft Certification Office, 1600 Stewart Avenue, Westbury, New York 11590; telephone (516) 2287327; fax (516) 7945531.