[Federal Register Volume 71, Number 26 (Wednesday, February 8, 2006)]
[Proposed Rules]
[Pages 6411-6413]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-1684]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-23798; Directorate Identifier 2005-NM-162-AD]
RIN 2120-AA64


Airworthiness Directives; Bombardier Model DHC-8-400 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking.

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Bombardier Model DHC-8-400 series airplanes. This proposed 
AD would require replacing all domed anchor nuts at all attachment 
locations of the upper fuel access panels of the center wing in the wet 
bay location with new nuts. This proposed AD results from reported 
cases of corroded dome anchor nuts at the attachment locations of the 
upper surface of the fuel access panel of the center wing. We are 
proposing this AD to prevent corrosion or perforation of domed anchor 
nuts, which could result in arcing and ignition of fuel vapor in the 
center wing fuel tank during a lightning strike and consequent 
explosion of the fuel tank.

DATES: We must receive comments on this proposed AD by March 10, 2006.

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.
     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.
    Contact Bombardier, Inc., Bombardier Regional Aircraft Division, 
123 Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada, for service 
information identified in this proposed 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) 228-7525; 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 in the ADDRESSES section. Include the docket number ``FAA-2006-
23798; Directorate Identifier 2005-NM-162-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 received 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 
that 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 may review the DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
may visit http://dms.dot.gov.

Examining the Docket

    You may 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 Docket Management System 
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 series airplanes. TCCA advises that, 
during ``2C'' checks, there have been a number of reported cases of 
corrosion of dome anchor nuts at the attachment locations of the upper 
surface of the fuel access panel of the center wing. In some cases, the 
dome anchor nuts were severely corroded and perforated. This condition, 
if not corrected, could result in arcing and ignition of fuel vapor in 
the center wing fuel tank during a lightning strike and consequent 
explosion of the fuel tank.

Relevant Service Information

    Bombardier has issued Service Bulletin 84-57-10, Revision ``A,'' 
dated March 14, 2005. The service bulletin describes procedures for 
replacing all domed anchor nuts at all attachment locations of the 
upper fuel access panels of the center wing in the wet bay location 
with new, corrosion-resistant anchor nuts. Accomplishing the actions 
specified in the service information is intended to adequately address 
the unsafe condition.
    The TCCA mandated the service information described previously, or 
Bombardier Service Bulletin 84-57-11,

[[Page 6412]]

dated February 25, 2004, or Revision ``A,'' dated March 9, 2004; and 
Bombardier Service Bulletin 84-57-12, dated March 11, 2005. The TCCA 
also issued Canadian airworthiness directive CF-2005-08R1, issued 
August 10, 2005, 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 
Sec.  21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the 
applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, the 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 airplanes of this type design that are certificated for 
operation in the United States.
    Therefore, we are proposing this AD, which would require 
accomplishing the actions specified in Bombardier Service Bulletin 84-
57-10, Revision ``A,'' dated March 14, 2005.

Differences Between the Proposed AD and the Canadian Airworthiness 
Directive

    Instead of doing the replacement specified in Bombardier Service 
Bulletin 84-57-10, Revision ``A,'' dated March 14, 2005, Canadian 
airworthiness directive mandates the inspections, installation, and 
corrective actions if necessary specified in Bombardier Service 
Bulletin 84-57-11, dated February 25, 2004, or Revision ``A,'' dated 
March 9, 2004; and Bombardier Service Bulletin 84-57-12, dated March 
11, 2005. The TCCA allows those actions because of the limited 
availability of new, corrosion-resistant anchor nuts.
    Since issuance of the Canadian airworthiness directive, the TCCA 
has advised us that corrosion-resistant anchor nuts are now available. 
Therefore, this proposed AD would require only the replacement 
specified in Bombardier Service Bulletin 84-57-10. In addition, the 
Canadian airworthiness directive requires the replacement within 9 
months after April 27, 2005 (the effective date of the Canadian 
airworthiness directive). However, this proposed AD would require the 
replacement within 3 months after the effective date of the AD. 
Deterioration of anchor nuts over time can cause the anchor nuts to 
become perforated, which could result in a potential source of ignition 
in a fuel tank and consequent fire or explosion. Therefore, we have 
determined that a compliance time of 3 months after the effective date 
of this AD is the maximum time allowable for all affected airplanes to 
continue to operate without compromising safety. TCCA agrees with our 
decision to mandate that replacement and to shorten the compliance 
time, which will align closer to their compliance date. Bombardier has 
been contacted, and they can support the part requirements.

Costs of Compliance

    This proposed AD would affect about 20 airplanes of U.S. registry. 
The proposed actions would take about 62 work hours per airplane, at an 
average labor rate of $65 per work hour. Required parts would cost 
about $300 per airplane. Based on these figures, the estimated cost of 
the proposed AD for U.S. operators is $86,600, or $4,330 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 and placed it in the AD docket. 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 Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

Bombardier, Inc. (Formerly de Havilland, Inc.): Docket No. FAA-2006-
23798; Directorate Identifier 2005-NM-162-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by March 10, 
2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Bombardier Model DHC-8-400 series 
airplanes, certificated in any category; serial numbers 4001, and 
4003 through 4115 inclusive.

Unsafe Condition

    (d) This AD results from reported cases of corroded dome anchor 
nuts at the attachment locations of the upper surface of the fuel 
access panel of the center wing. We are issuing this AD to prevent 
corrosion or perforation of domed anchor nuts, which could result in 
arcing and ignition of fuel vapor in the center wing fuel tank 
during a lightning strike and consequent explosion of the fuel tank.

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.

[[Page 6413]]

Replacement With Corrosion Resistant Anchor Nuts

    (f) At the applicable time in Table 1 of this AD, replace all 
domed anchor nuts at all attachment locations of the upper fuel 
access panels of the center wing in the wet bay location with new, 
corrosion-resistant anchor nuts. Do all the actions in accordance 
with the Accomplishment Instructions of Bombardier Service Bulletin 
84-57-10, Revision `A,' dated March 14, 2005.

                        Table 1.--Compliance Time
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                                  On which the
 For airplanes having serial      inspection(s)      Do the replacement
          number(s)               specified in
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(1) 4108 through 4115         None................  Within 48 months
 inclusive.                                          after the date of
                                                     issuance of the
                                                     original standard
                                                     Canadian
                                                     airworthiness
                                                     certificate or the
                                                     date of issuance of
                                                     the original
                                                     Canadian export
                                                     certificate of
                                                     airworthiness, or
                                                     within 2 months
                                                     after the effective
                                                     date of this AD,
                                                     whichever occurs
                                                     later.
(2) 4001, and 4003 through    Bombardier Service    Within 24 months
 4107 inclusive.               Bulletin 84-57-11,    after those
                               dated February 25,    inspections, or
                               2005; or Revision     within 2 months
                               `A,' dated March 9,   after the effective
                               2005; have been       date of this AD,
                               done before the       whichever occurs
                               effective date of     later.
                               this AD.
                              Bombardier Service    Within 48 months
                               Bulletin 84-57-12,    after that
                               dated March 11,       inspection, or
                               2005, has been done   within 2 months
                               before the            after the effective
                               effective date of     date of this AD,
                               this AD.              whichever occurs
                                                     later.
                              Bombardier Service    Within 3 months
                               Bulletin 84-57-11,    after the effective
                               dated February 25,    date of this AD.
                               2005, or Revision
                               `A,' dated March 9,
                               2005; or Bombardier
                               Service Bulletin 84-
                               57-12, dated March
                               11, 2005; has not
                               been done before
                               the effective date
                               of this AD.
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Alternative Methods of Compliance (AMOCs)

    (g)(1) 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.
    (2) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.

Related Information

    (h) Canadian airworthiness directive CF-2005-08R1, issued August 
10, 2005, also addresses the subject of this AD.

    Issued in Renton, Washington, on January 26, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E6-1684 Filed 2-7-06; 8:45 am]
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