Airworthiness Directives; Bombardier Model CL-600-2C10 (Regional Jet Series 700 & 701) Series Airplanes, and Model CL-600-2D24 (Regional Jet Series 900) Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Bombardier Model CL-600-2C10 (Regional Jet Series 700 & 701) series airplanes, and Model CL-600-2D24 (Regional Jet Series 900) series airplanes. This proposed AD would require revising the Airworthiness Limitations section of the Instructions of Continued Airworthiness by incorporating new repetitive inspections and an optional terminating action for the repetitive inspections, and would require repairing any crack. This proposed AD is prompted by reports of hydraulic pressure loss in either the number 1 or number 2 hydraulic systems due to breakage or leakage of hydraulic lines in the aft equipment bay and reports of cracks on the aft pressure bulkhead web around these feed-through holes. We are proposing this AD to prevent loss of hydraulic pressure, which could result in reduced controllability of the airplane and to detect and correct cracks on the aft pressure bulkhead web, which could result in reduced structural integrity of the aft pressure bulkhead.

DATES:

We must receive comments on this proposed AD by January 3, 2005.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, Washington, DC 20590.

By fax: (202) 493-2251.

• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact Bombardier, Inc., Canadair, Aerospace Group, P.O. Box 6087, Station Centre-ville, Montreal, Quebec H3C 3G9, Canada.

You can examine the contents of this AD docket on the Internet at http://dms.dot.gov , or in person at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., room PL-401, on the plaza level of the Nassif Building, Washington, DC. This docket number is FAA-2004-19754; the directorate identifier for this docket is 2004-NM-181-AD.

FOR FURTHER INFORMATION CONTACT:

Technical information: Serge Napoleon, Aerospace Engineer, Airframe and Propulsion Branch, ANE-171, FAA, New York Aircraft Certification Office, 1600 Stewart Avenue, suite 410, Westbury, New York 11590; telephone (516) 228-7312; fax (516) 794-5531.

Plain language information: Marcia Walters, marcia.walters@faa.gov.

SUPPLEMENTARY INFORMATION:

Docket Management System (DMS)

The FAA has implemented new procedures for maintaining AD dockets electronically. As of May 17, 2004, new AD actions are posted on DMS and assigned a docket number. We track each action and assign a corresponding directorate identifier. The DMS AD docket number is in the form “Docket No. FAA-2004-99999.” The Transport Airplane Directorate identifier is in the form “Directorate Identifier 2004-NM-999-AD.” Each DMS AD docket also lists the directorate identifier (“Old Docket Number”) as a cross-reference for searching purposes.

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2004-19754; Directorate Identifier 2004-NM-181-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments submitted by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov , including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of our docket Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You can review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you can visit http://dms.dot.gov .

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications that affect you. You can get more information about plain language at http://www.faa.gov/language and http://www.plainlanguage.gov .

Examining the Docket

You can examine the AD docket on the Internet at http://dms.dot.gov,, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the DMS receives them.

Discussion

Transport Canada Civil Aviation (TCCA), which is the airworthiness authority for Canada, notified us that an unsafe condition may exist on certain Bombardier Model CL-600-2C10 (Regional Jet Series 700 & 701) series airplanes, and Model CL-600-2D24 (Regional Jet Series 900) series airplanes. TCCA advises that there have been a number of reported cases of hydraulic pressure loss in either the number 1 or number 2 hydraulic systems due to breakage or leakage of hydraulic lines in the aft equipment bay. In some cases, hydraulic lines and connector jam nuts were found loose at the aft pressure bulkhead web. Loosening of the jam nuts also resulted in elongation of the affected feed-through holes on the aft pressure bulkhead web at fuselage station 1098.2, stringers 8 and 9, left- and right-hand sides. In addition, cracks were found on the aft pressure bulkhead web around these feed-through holes. Loss of hydraulic pressure, if not corrected, could result in reduced controllability of the airplane. Cracks on the aft pressure bulkhead web, if not detected and corrected, could result in reduced structural integrity of the aft pressure bulkhead.

Relevant Service Information

Bombardier has issued CRJ 700/900 Series Temporary Revision (TR) MRM2-129, dated June 1, 2004. The TR describes procedures for new repetitive inspections of the aft pressure bulkhead and pylon pressure pan in the vicinity of the hydraulic fittings, and the hydraulic tube adapters. The TR also describes an optional terminating action for the repetitive inspections. Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition. TCCA mandated the service information and issued Canadian airworthiness directive CF-2004-14, dated July 20, 2004, to ensure the continued airworthiness of these airplanes in Canada.

FAA's Determination and Requirements of the Proposed AD

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. We have examined TCCA's findings, evaluated all pertinent information, and determined that we need to issue an AD for products of this type design that are certificated for operation in the United States.

Therefore, we are proposing this AD, which would require revising the Airworthiness Limitations section of the Instructions of Continued Airworthiness by incorporating new repetitive inspections and an optional terminating action for the repetitive inspections, and would require repairing any crack.

Differences Between the Proposed AD and Canadian Airworthiness Directive

Canadian airworthiness directive CF-2004-14 specifies that you may contact the manufacturer for instructions on how to repair certain conditions, but this proposed AD would require you to repair those conditions using a method that we or TCAA (or its delegated agent) approve. In light of the type of repair that would be required to address the unsafe condition, and consistent with existing bilateral airworthiness agreements, we have determined that, for this proposed AD, a repair we or TCAA approve would be acceptable for compliance with this proposed AD.

Costs of Compliance

This proposed AD would affect about 116 airplanes of U.S. registry. The proposed actions would take about 1 work hour per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of the proposed AD for U.S. operators is $7,540, or $65 per airplane.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD 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.

For the reasons discussed above, I certify that the 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. 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.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD. See the ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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.