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Proposed Rule

Airworthiness Directives; Bombardier Model DHC-7 Series Airplanes

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Bombardier Model DHC-7 series airplanes. This proposed AD would require revising the Airworthiness Limitations section of the Instructions of Continued Airworthiness to include a new lower life limit for lower wing skins. This proposed AD is prompted by the discovery that during the manufacture of the lower wing skins, score marks may have been accidentally inscribed around the edge of the lower wing skin doublers. We are proposing this AD to prevent fatigue cracks from developing at the score marks in the lower wing skins, which could result in the structural failure of the wing.

DATES:

We must receive comments on this proposed AD by April 14, 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., Bombardier Regional Aircraft Division, 123 Garratt Boulevard, Downsview, Ontario M3K 1Y5, 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-2005-20595; the directorate identifier for this docket is 2004-NM-149-AD.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

David Lawson, 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) 228-7327; fax (516) 794-5531.

End Further Info End Preamble Start Supplemental Information

SUPPLEMENTARY INFORMATION:

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-2005-20595; Directorate Identifier 2004-NM-149-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.

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 DHC-7 series airplanes. TCCA advises that during the manufacture of the wing bottom skins, score marks may have been accidentally inscribed around the edge of the lower wing skin doublers. Wing stations YW180 to YW375 were identified as the locations where these scores could result in a reduced wing life. Bombardier evaluated the lower wing skin with score marks 0.003 inch in depth and determined that a wing life of 60,000 flights must be introduced. This condition, if not corrected, could result in fatigue cracks developing at the score marks and could result the structural failure of the wing.

Relevant Service Information

Bombardier has issued Temporary Revision (TR) 5-103 to Chapter 5-10-11 of the DHC-7 Maintenance Manual (PSM 1-7-2), dated March 26, 2004, which adds a new life limit of 60,000 flights for the DHC-7 lower wing skins to prevent a structural failure of the wing. 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-2004-12, dated June 28, 2004, to ensure the continued airworthiness of these airplanes in Canada.

FAA's Determination and Requirements of the Proposed AD

This airplane model is manufactured in Canada and is type certificated for Start Printed Page 12615operation 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, TCCA has kept the FAA informed of the situation described above. We have examined the 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 to include a new lower life limit for certain lower wing skins. The proposed AD would require you to use the service information described previously to perform these actions.

Clarification of Actions in the Canadian Airworthiness Directive and the Proposed AD

The Canadian airworthiness directive specifies that the operator's maintenance schedule be revised to incorporate a new life limit for the lower skins and that, before reaching the life limit, wings having lower wing skins be removed from service. This proposed AD would only require revising the Airworthiness Limitations section of the Instructions of Continued Airworthiness to require the new life limit. Once that document is revised, as required, and the proposed AD has been fully complied with, the life limit remains enforceable as a part of the Airworthiness Limitations section in accordance with 14 CFR 91.403(c). As no lower wing skin is near the life limit, only the revision to the Airworthiness Limitation section is necessary to address the unsafe condition.

Costs of Compliance

This proposed AD would affect about 3 airplanes of U.S. registry. The proposed revision of the Airworthiness Limitations section 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 $195, or $65 per airplane.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in subtitle VII, part A, subpart III, section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

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.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End List of Subjects

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

Start Part

PART 39—AIRWORTHINESS DIRECTIVES

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

Start Authority

Authority: 49 U.S.C. 106(g), 40113, 44701.

End Authority
[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):

Bombardier, Inc. (Formerly de Havilland, Inc.): Docket No. FAA-2005-20595; Directorate Identifier 2004-NM-149-AD.

Comments Due Date

(a) The Federal Aviation Administration must receive comments on this AD action by April 14, 2005.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Bombardier Model DHC-7 series airplanes, serial numbers 3 through 10 inclusive, 12 through 14 inclusive, and 16 through 27 inclusive; certificated in any category.

Note 1:

This AD requires revision to a certain operator maintenance document to include a new replacement time. Compliance with this replacement time is required by 14 CFR 91.403(c). For airplanes that have been previously modified, altered, or repaired in the areas addressed by this replacement time, the operator may not be able to accomplish the replacement described in the revision. In this situation, to comply with 14 CFR 91.403(c), the operator must request approval for an alternative method of compliance according to paragraph (i) of this AD. The request should include a description of changes to the required replacement time that will ensure the continued damage tolerance of the affected structure. The FAA has provided guidance for this determination in Advisory Circular (AC) 25-1529.

Unsafe Condition

(d) This AD is prompted by the discovery that during the manufacture of the lower wing skins, score marks may have been accidentally inscribed around the edge of the lower wing skin doublers. We are issuing this AD to prevent fatigue cracks from developing at the score marks in the lower wing skins, which could result in the structural failure of the wing.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Revise the Airworthiness Limitations (AWL) Section—New Life Limit

(f) Within 30 days after the effective date of this AD, revise the AWL section of the Instructions for Continued Airworthiness to incorporate new life limits for the lower wing skins by incorporating Bombardier Temporary Revision (TR) 5-103, dated March 26, 2004, to the Bombardier DHC-7 Maintenance Manual (PSM 1-7-2), into the AWL section.

(g) When the contents of TR 5-103 have been included in the general revisions of the AWL section, the general revisions may be incorporated into the AWL section, and the TR may be removed from the AWL section.

(h) After the actions specified in paragraphs (f) of this AD have been accomplished, no alternative life limits may be approved for the lower wing skins, except as provided in paragraph (i) of this AD.

Alternative Methods of Compliance (AMOCs)

(i) The Manager, New York Aircraft Certification Office, FAA, has the authority to Start Printed Page 12616approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

Related Information

(j) Canadian airworthiness directive CF-2004-12, dated June 28, 2004, also addresses the subject of this AD.

Start Signature

Issued in Renton, Washington, on March 7, 2005.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

End Signature End Part End Supplemental Information

[FR Doc. 05-5012 Filed 3-14-05; 8:45 am]

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