[Federal Register Volume 70, Number 49 (Tuesday, March 15, 2005)]
[Proposed Rules]
[Pages 12614-12616]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-5012]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-20595; Directorate Identifier 2004-NM-149-AD]
RIN 2120-AA64


Airworthiness Directives; Bombardier Model DHC-7 Series Airplanes

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

ACTION: Notice of proposed rulemaking (NPRM).

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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:// http://dms.dot.gov">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.

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.

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://
http://dms.dot.gov">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://
http://dms.dot.gov">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

[[Page 12615]]

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, 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.

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.


Sec.  39.13  [Amended]

    2. The FAA amends Sec.  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

[[Page 12616]]

approve 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.

    Issued in Renton, Washington, on March 7, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-5012 Filed 3-14-05; 8:45 am]
BILLING CODE 4910-13-P