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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 2000-NM-347-AD] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Notice of proposed rulemaking (NPRM). 

# SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Bombardier Model DHC-8-100, -200, and -300 series airplanes. This proposal would require removing certain foam filters from the cabin ducting installation located below the dado panels on the left- and right-hand sides of the airplane. This action is necessary to prevent an increased risk of spreading a fire or failure of the cabin to pressurize adequately if certain foam filters are installed. This action is intended to address the identified unsafe condition. 

# DATES:

Comments must be received by March 16, 2001. 

# ADDRESSES:

                        Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-347-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 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. 2000-NM-347-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.                               ( print page 10233)    

The service information referenced in the proposed rule may be obtained from Bombardier, Inc., Bombardier Regional Aircraft Division, 123 Garratt Boulevard, Downsview, Ontario M3K 1Y5, 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, 10 Fifth Street, Third Floor, Valley Stream, New York. 

# FOR FURTHER INFORMATION CONTACT:

Dan Parrillo, Aerospace Engineer, Systems and Flight Test Branch, ANE-172, FAA, New York Aircraft Certification Office, 10 Fifth Street, Third Floor, Valley Stream, New York 11581; telephone (516) 256-7505; fax (516) 568-2716. 

# 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 notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-347-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. 2000-NM-347-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

## Discussion 

Transport Canada Civil Aviation (TCCA), which is the airworthiness authority for Canada, notified the FAA that an unsafe condition may exist on certain Bombardier Model DHC-8-100, -200, and -300 series airplanes. TCCA advises that certain foam filters for the cabin exhaust system were incorporated erroneously on production airplanes. (There is no requirement that these filters be installed.) These filters failed to pass the flammability tests specified in Appendix F of part 25 of the Federal Aviation Regulations (14 CFR part 25). This condition, if not corrected, could increase the risk of spreading a fire on the airplane. 

In addition, pressurization tests are required by § 25.843(b) of the Federal Aviation Regulations [14 CFR 25.843(b)]; however, these tests were conducted without foam filters installed in the cabin exhaust system of the airplane. The impact on pressurization of the airplane to proper levels is unknown for airplanes on which these filters are installed; therefore, pressurization tests would have to be reaccomplished on any airplane having the filters. Installation of these filters could result in failure of the cabin to pressurize adequately. 

## Explanation of Relevant Service Information 

The manufacturer has issued Bombardier Repair Drawing RD8-21-23, Issue 2, dated December 16, 1999, which describes procedures for removing certain foam filters from the cabin ducting installation located below the dado panels on the left- and right-hand sides of the airplane. These procedures include: verifying that certain foam filters are installed behind the grille assemblies, inspecting the grille assemblies on both the port and starboard sides and along the entire length of the interior of the airplane, removing all foam filters and ensuring that no pieces remain, and reinstalling the grille assemblies by locating the fasteners and pressing each with a quarter-turn. Accomplishment of the actions specified in the repair drawing is intended to adequately address the identified unsafe condition. TCCA classified this repair drawing as mandatory and issued Canadian airworthiness directive CF-2000-25, dated August 28, 2000, 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 require accomplishment of the actions specified in the repair drawing described previously. 

## Cost Impact 

The FAA estimates that 38 Bombardier Model DHC-8-100, -200, and -300 series airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 8 work hours per airplane to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $18,240, or $480 per airplane. 

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the 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                           ( print page 10234)                        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. 

§ 39.13 

2. Section 39.13 is amended by adding the following new airworthiness directive: 

**Bombardier, Inc.**                                 (Formerly de Havilland, Inc.): Docket 2000-NM-347-AD.                            

*Applicability:*                                 Model DHC-8-100, -200, and -300 series airplanes, certificated in any category, having serial numbers 408, 413, 434 through 463 inclusive, 465 through 489 inclusive, 491 through 505 inclusive, and 507.                             

# Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (b) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

*Compliance:*                                 Required as indicated, unless accomplished previously.                             

To prevent an increased risk of spreading a fire, or failure of the cabin to pressurize adequately if certain foam filters are installed, accomplish the following: 

## Removal of Foam Filters 

(a) Within 4 months after the effective date of this AD, remove the foam filters from the cabin ducting installation located below the dado panels on the left- and right-hand sides of the airplane (including verifying that the foam filters are installed behind the grille assemblies, inspecting the grille assemblies on both the port and starboard sides and along the entire length of the interior of the airplane, removing all foam filters and ensuring that no pieces remain, and reinstalling the grille assemblies by locating the fasteners and pressing each with a quarter-turn), per Bombardier Aerospace Repair Drawing RD8-21-23, Issue 2, dated December 16, 1999. 

## Alternative Methods of Compliance 

(b) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, New York Aircraft Certification Office (ACO), FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, New York ACO. 

# Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the New York ACO.

## Special Flight Permits 

(c) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. 

# Note 3:

The subject of this AD is addressed in Canadian airworthiness directive CF-2000-25, dated August 28, 2000. 

Issued in Renton, Washington, on February 7, 2001. 

Dorenda D. Baker, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 01-3677 Filed 2-13-01; 8:45 am] 

BILLING CODE 4910-13-U