AD 95-13-04

Effective August 14, 1995, to all persons except those persons to whom it was made immediately effective by priority letter AD 95-13-04, issued on June 16, 1995, which contained the requirements of this amendment.

Comments for inclusion in the Rules Docket must be received on or before September 26, 1995.

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 95-NM-116-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

The applicable service information may be obtained from 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 11581; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Peter Cuneo, Electrical Engineer, Systems and Equipment Branch, ANE-173, FAA, Engine and Propeller Directorate, New York Aircraft Certification Office, 10 Fifth Street, Third Floor, Valley Stream, New York 11581; telephone (516) 256-7506; fax (516) 568-2716.

On June 16, 1995, the FAA issued priority letter AD 95-13-04, applicable to certain Bombardier Model CL-600-2B19 (Regional Jet Series 100) series airplanes. Transport Canada Aviation, which is the airworthiness authority for Canada, recently notified the FAA that, during a recent Canadair review of vendor documentation of the horizontal stabilizer trim control unit (HSTCU), certain deficiencies were discovered. The reliability of the HSTCU was found to be lower than anticipated due to circuit design deficiencies. When such deficiencies exist in the HSTCU, and a single component in the mach trim circuits fails, a nose-up trim runaway could occur.

Bombardier has issued Canadair Regional Jet Temporary Revision No. TR RJ/43 to the Airplane Flight Manual (AFM). This temporary revision advises the flightcrew that the use of mach trim is prohibited and that speed restrictions must be applied if the autopilot is disengaged or inoperative. Transport Canada Aviation issued Canadian airworthiness directive CF95-08, dated June 8, 1995, in order to assure the continued airworthiness of these airplanes in Canada.

This airplane model is manufactured in Canada and is type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, Transport Canada Aviation has kept the FAA informed of the situation described above. The FAA has examined the findings of Transport Canada Aviation, 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.

Since the unsafe condition described is likely to exist or develop on other airplanes of the same type design registered in the United States, the FAA issued priority letter AD 95-13-04 to require a revision to the Limitations Section of the FAA-approved AFM to prohibit the use of mach trim and to add speed restrictions if the autopilot is disengaged or inoperative. The actions are required to be accomplished in accordance with the temporary revision to the AFM previously described.

In addition, the FAA finds that in order to ensure flightcrew awareness, the installation of a placard is necessary to advise the flightcrew of the operations restrictions discussed previously.

This AD is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking.

Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual letters issued on June 16, 1995, to all known U.S. owners and operators of certain Bombardier Model CL-600-2B19 (Regional Jet Series 100) series airplanes. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective as to all persons.

Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 95-NM-116-AD.'' The postcard will be date stamped and returned to the commenter.

The regulations adopted herein will not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a ``significant regulatory action'' under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption ADDRESSES.

Air transportation, Aircraft, Aviation safety, Safety.

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

1. The authority citation for part 39 is revised to read as follows:

Authority: 49 USC 106(g), 40101, 40113, 44701.