[Federal Register Volume 70, Number 65 (Wednesday, April 6, 2005)]
[Proposed Rules]
[Pages 17354-17356]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-6764]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-20860; Directorate Identifier 2005-NM-043-AD]
RIN 2120-AA64


Airworthiness Directives; Bombardier Model DHC-8-400, -401, and -
402 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-8-400, -401, and -402 airplanes. This 
proposed AD would require revising the

[[Page 17355]]

Airworthiness Limitation section of the Instructions for Continued 
Airworthiness of the Dash 8 400 Series (Bombardier) Maintenance 
Requirements Manual to reduce the life limits of the main landing gear 
(MLG) orifice support tube, upper bearing, and piston plug; and to 
reduce the threshold for initiating repetitive detailed inspections for 
cracking of the engine isolator brackets. This proposed AD is prompted 
by the discovery of fatigue failures, during type certification fatigue 
testing, at the engine isolator bracket and at the orifice support 
tube, upper bearing, and piston plug in the shock strut assembly of the 
MLG, which are principal structural elements. We are proposing this AD 
to prevent the development of cracks in these principal structural 
elements, which could reduce the structural integrity of the engine 
installation and the MLG. Reduced structural integrity of the engine 
installation could result in separation of the engine from the 
airplane, and reduced structural integrity of the MLG could result in 
collapse of the MLG.

DATES: We must receive comments on this proposed AD by May 6, 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-2005-20860; the directorate identifier for this 
docket is 2005-NM-043-AD.

FOR FURTHER INFORMATION CONTACT: George Duckett, 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) 228-7325; 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-2005-20860; 
Directorate Identifier 2005-NM-043-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 website, 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-8-400, -401, and -402 airplanes. TCAA 
advises that, during type certification fatigue testing, fatigue 
failures were discovered at the engine isolator bracket and at the 
orifice support tube, upper bearing, and piston plug in the shock strut 
assembly of the main landing gear (MLG), which are principal structural 
elements. The development of cracks in these principal structural 
elements, if not prevented, could reduce the structural integrity of 
the engine installation and MLG. Reduced structural integrity of the 
engine installation could result in separation of the engine from the 
airplane, and reduced structural integrity of the MLG could result in 
collapse of the MLG.

Relevant Service Information

    Bombardier has issued the following temporary revisions (TRs) to 
the Dash 8 Series 400 (Bombardier) Maintenance Requirements Manual, PSM 
1-84-7:
     Dash 8 Series 400 (Bombardier) TR ALI-28, dated December 
11, 2003; and
     Dash 8 Series 400 (Bombardier) TR ALI-37, dated March 30, 
2004
    TR ALI-28 describes procedures for reducing the life limits of the 
MLG orifice support tube having part number (P/N) 46117-1, upper 
bearing having P/N 46114-1, and piston plug having P/N 46137-1. TR ALI-
37 describes procedures for incorporating certain structural inspection 
tasks to reduce the threshold for initiating repetitive detailed 
inspections for cracking of the engine isolator brackets. The TCAA 
mandated the TRs and issued Canadian airworthiness directive CF-2004-
19, dated September 21, 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 
section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and 
the applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, the TCAA has kept the FAA informed 
of the situation described above. We have examined the TCAA'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 Limitation section of the Instructions for Continued 
Airworthiness of the Dash 8 Series 400 (Bombardier) Maintenance 
Requirements Manual, PSM 1-84-7, to reduce the life limits of the MLG 
orifice

[[Page 17356]]

support tube, upper bearing, and piston plug; and to reduce the 
threshold for initiating repetitive detailed inspections for cracking 
of the engine isolator brackets. This AD would require accomplishing 
the actions specified in the TRs described previously.

Interim Action

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

Costs of Compliance

    There are about 93 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 21 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 
$1,365, 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-
20860; Directorate Identifier 2005-NM-043-AD.

Comments Due Date

    (a) The Federal Aviation Administration must receive comments on 
this AD action by May 6, 2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Bombardier Model DHC-8-400, -401, and -
402 airplanes; certificated in any category; serial numbers 4001 and 
4003 through 4094 inclusive.

    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 (g) 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 was prompted by the discovery of fatigue failures, 
during type certification fatigue testing, at the engine isolator 
bracket and at the orifice support tube, upper bearing, and piston 
plug in the shock strut assembly of the main landing gear (MLG), 
which are principal structural elements. We are issuing this AD to 
prevent the development of cracks in these principal structural 
elements, which could reduce the structural integrity of the engine 
installation and MLG. Reduced structural integrity of the engine 
installation could result in separation of the engine from the 
airplane, and reduced structural integrity of the MLG could result 
in collapse of the MLG.

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.

Revisions to Airworthiness Limitation (AWL) Section

    (f) Within 30 days after the effective date of this AD, revise 
the AWL section of the Instructions for Continued Airworthiness of 
the Dash 8 Series 400 (Bombardier) Maintenance Requirements Manual, 
PSM 1-84-7, by doing the actions specified in paragraphs (f)(1) and 
(f)(2) of this AD.
    (1) Reduce the life limits of the MLG orifice support tube 
having part number (P/N) 46117-1, upper bearing having P/N 46114-1, 
and piston plug having P/N 46137-1, by inserting a copy of the Dash 
8 Series 400 (Bombardier) Temporary Revision ALI-28, dated December 
11, 2003, into the AWL section. Thereafter, except as provided in 
paragraph (g) of this AD, no alternative life limits may be approved 
for the MLG orifice support tube, upper bearing, or piston plug.
    (2) Incorporate structural inspection tasks 712001F102 and 
712003F102 to reduce the threshold for initiating repetitive 
detailed inspections for cracking of the engine isolator brackets by 
inserting a copy of the Dash 8 Series 400 (Bombardier) Temporary 
Revision ALI-37, dated March 30, 2004, into the AWL section. 
Thereafter, except as provided in paragraph (g) of this AD, no 
alternative structural inspection threshold may be approved.

Alternative Methods of Compliance (AMOCs)

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

Related Information

    (h) Canadian airworthiness directive CF-2004-19, dated September 
21, 2004, also addresses the subject of this AD.

    Issued in Renton, Washington, on March 30, 2005.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-6764 Filed 4-5-05; 8:45 am]
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