[Federal Register Volume 73, Number 48 (Tuesday, March 11, 2008)]
[Proposed Rules]
[Pages 12907-12910]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-4771]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0267; Directorate Identifier 2008-NM-030-AD]
RIN 2120-AA64


Airworthiness Directives; Bombardier Model DHC-8-400, DHC-8-401, 
and DHC-8-402 Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

[[Page 12908]]


ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for the 
products listed above. This proposed AD results from mandatory 
continuing airworthiness information (MCAI) originated by an aviation 
authority of another country to identify and correct an unsafe 
condition on an aviation product. The MCAI describes the unsafe 
condition as:

    Bombardier Aerospace has completed a system safety review of the 
aircraft fuel system against fuel tank safety standards introduced 
in Chapter 525 of the Airworthiness Manual through Notice of 
Proposed Amendment (NPA) 2002-043. The identified non-compliances 
were then assessed using Transport Canada Policy Letter No. 525-001, 
to determine if mandatory corrective action is required.

    The assessment showed that it is necessary to introduce Critical 
Design Configuration Control Limitations (CDCCL), in order to 
preserve critical fuel tank system ignition source prevention 
features during configuration changes such as modifications and 
repairs, or during maintenance actions. Failure to preserve critical 
fuel tank system ignition source prevention features could result in 
a fuel tank explosion. * * *

The proposed AD would require actions that are intended to address the 
unsafe condition described in the MCAI.

DATES: We must receive comments on this proposed AD by April 10, 2008.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: (202) 493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-40, 1200 New 
Jersey Avenue SE., Washington, DC, between 9 a.m. and 5 p.m., Monday 
through Friday, except Federal holidays.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Operations office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Operations office (telephone (800) 647-5527) is 
in the ADDRESSES section. Comments will be available in the AD docket 
shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Richard Fiesel, 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) 228-7304; fax (516) 794-5531.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2008-0267; 
Directorate Identifier 2008-NM-030-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD based on those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    Transport Canada Civil Aviation (TCCA), which is the aviation 
authority for Canada, has issued Canadian Airworthiness Directive CF-
2008-06, dated January 15, 2008 (referred to after this as ``the 
MCAI''), to correct an unsafe condition for the specified products. The 
MCAI states:

    Bombardier Aerospace has completed a system safety review of the 
aircraft fuel system against fuel tank safety standards introduced 
in Chapter 525 of the Airworthiness Manual through Notice of 
Proposed Amendment (NPA) 2002-043. The identified non-compliances 
were then assessed using Transport Canada Policy Letter No. 525-001, 
to determine if mandatory corrective action is required.
    The assessment showed that it is necessary to introduce Critical 
Design Configuration Control Limitations (CDCCL), in order to 
preserve critical fuel tank system ignition source prevention 
features during configuration changes such as modifications and 
repairs, or during maintenance actions. Failure to preserve critical 
fuel tank system ignition source prevention features could result in 
a fuel tank explosion. Revisions have been made to Part 2 
``Airworthiness Limitations Items'' of the Maintenance Requirements 
Manual of the affected models to introduce the required CDCCL.

The corrective action is revising the Airworthiness Limitations Section 
of the Instructions for Continued Airworthiness to include the CDCCL 
data. You may obtain further information by examining the MCAI in the 
AD docket.
    The FAA has examined the underlying safety issues involved in fuel 
tank explosions on several large transport airplanes, including the 
adequacy of existing regulations, the service history of airplanes 
subject to those regulations, and existing maintenance practices for 
fuel tank systems. As a result of those findings, we issued a 
regulation titled ``Transport Airplane Fuel Tank System Design Review, 
Flammability Reduction and Maintenance and Inspection Requirements'' 
(66 FR 23086, May 7, 2001). In addition to new airworthiness standards 
for transport airplanes and new maintenance requirements, this rule 
included Special Federal Aviation Regulation No. 88 (``SFAR 88,'' 
Amendment 21-78, and subsequent Amendments 21-82 and 21-83).
    Among other actions, SFAR 88 requires certain type design (i.e., 
type certificate (TC) and supplemental type certificate (STC)) holders 
to substantiate that their fuel tank systems can prevent ignition 
sources in the fuel tanks. This requirement applies to type design 
holders for large turbine-powered transport airplanes and for 
subsequent modifications to those airplanes. It requires them to 
perform design reviews and to develop design changes and maintenance 
procedures if their designs do not meet the new fuel tank safety 
standards. As explained in the preamble to the rule, we intended to 
adopt airworthiness directives to mandate any changes found necessary 
to address unsafe conditions identified as a result of these reviews.
    In evaluating these design reviews, we have established four 
criteria intended to define the unsafe conditions associated with fuel 
tank systems that require corrective actions. The percentage of 
operating time during which fuel tanks are exposed to flammable 
conditions is one of these criteria. The other three criteria address 
the failure types under evaluation: Single failures, single failures in 
combination with a latent condition(s), and in-service failure 
experience. For all four criteria, the evaluations included 
consideration of previous actions taken that may mitigate the need for 
further action.
    We have determined that the actions identified in this AD are 
necessary to reduce the potential of ignition sources inside fuel 
tanks, which, in combination with flammable fuel vapors, could result

[[Page 12909]]

in fuel tank explosions and consequent loss of the airplane.

Relevant Service Information

    Bombardier has issued Temporary Revisions (TRs) ALI-55 and ALI-56, 
both dated April 19, 2006, to Part 2, ``Airworthiness Limitations 
Items,'' (AWL) of the Bombardier Dash 8 Q400 Maintenance Requirements 
Manual PSM 1-84-7. The actions described in this service information 
are intended to correct the unsafe condition identified in the MCAI.

FAA's Determination and Requirements of This Proposed AD

    This product has been approved by the aviation authority of another 
country, and is approved for operation in the United States. Pursuant 
to our bilateral agreement with the State of Design Authority, we have 
been notified of the unsafe condition described in the MCAI and service 
information referenced above. We are proposing this AD because we 
evaluated all pertinent information and determined an unsafe condition 
exists and is likely to exist or develop on other products of the same 
type design.
    This proposed AD would allow revising the Airworthiness Limitations 
Section (ALS) of the Instructions for Continued Airworthiness in 
accordance with later revisions of the maintenance requirements manual 
(MRM) as an acceptable method of compliance if the CDCCL is part of a 
later approved MRM revision, or if the CDCCL is approved as an 
alternative method of compliance (AMOC) in accordance with the 
procedures specified in paragraph (g)(1) of this proposed AD.
    In most ADs, we adopt a compliance time allowing a specified amount 
of time after the AD's effective date. In this case, however, the FAA 
has already issued regulations that require operators to revise their 
maintenance/inspection programs to address fuel tank safety issues. The 
compliance date for these regulations is December 16, 2008. To provide 
for coordinated implementation of these regulations and this proposed 
AD, we are using this same compliance date in this proposed AD.

Differences Between This AD and the MCAI or Service Information

    We have reviewed the MCAI and related service information and, in 
general, agree with their substance. But we might have found it 
necessary to use different words from those in the MCAI to ensure the 
AD is clear for U.S. operators and is enforceable. In making these 
changes, we do not intend to differ substantively from the information 
provided in the MCAI and related service information.
    We might also have proposed different actions in this AD from those 
in the MCAI in order to follow FAA policies. Any such differences are 
highlighted in a NOTE within the proposed AD.

Costs of Compliance

    Based on the service information, we estimate that this proposed AD 
would affect about 45 products of U.S. registry. We also estimate that 
it would take about 1 work-hour per product to comply with the basic 
requirements of this proposed AD. The average labor rate is $80 per 
work-hour. Based on these figures, we estimate the cost of the proposed 
AD on U.S. operators to be $3,600, or $80 per product.

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 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 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. 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.

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 AD:

Bombardier, Inc. (Formerly de Havilland, Inc.): Docket No. FAA-2008-
0267; Directorate Identifier 2008-NM-030-AD.

Comments Due Date

    (a) We must receive comments by April 10, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all Bombardier Model DHC-8-400, DHC-8-
401, and DHC-8-402 airplanes, certificated in any category, all 
serial numbers.

Subject

    (d) Air Transport Association (ATA) of America Code 28: Fuel.

Reason

    (e) The mandatory continuing airworthiness information (MCAI) 
states:

Bombardier Aerospace has completed a system safety review of the 
aircraft fuel system against fuel tank safety standards introduced 
in Chapter 525 of the Airworthiness Manual through Notice of 
Proposed Amendment (NPA) 2002-043. The identified non-compliances 
were then assessed using Transport Canada Policy Letter No. 525-001, 
to determine if mandatory corrective action is required.

The assessment showed that it is necessary to introduce Critical 
Design Configuration Control Limitations (CDCCL), in order to 
preserve critical fuel tank system ignition source prevention 
features during configuration changes such as modifications and 
repairs, or during maintenance actions. Failure to preserve critical 
fuel tank system ignition source prevention features could result in 
a fuel tank explosion. Revisions have been made to Part 2 
``Airworthiness Limitations Items'' of the Maintenance

[[Page 12910]]

Requirements Manual of the affected models to introduce the required 
CDCCL.

The corrective action is revising the Airworthiness Limitations 
Section (ALS) of the Instructions for Continued Airworthiness to 
include the CDCCL data.

Actions and Compliance

    (f) Unless already done, do the following actions.
    (1) For all airplanes: Within 60 days after the effective date 
of this AD, or before December 16, 2008, whichever occurs first, 
revise the ALS of the Instructions for Continued Airworthiness to 
incorporate the CDCCLs specified in Bombardier Temporary Revisions 
(TRs) ALI-55, dated April 19, 2006; and ALI-56, dated April 19, 
2006; to Part 2, ``Airworthiness Limitations Items,'' of the 
Bombardier Dash 8 Q400 Maintenance Requirements Manual (MRM) PSM 1-
84-7.


    Note 1: The actions required by paragraph (f)(1) of this AD may 
be done by inserting a copy of the applicable TR into the applicable 
maintenance requirements manual. When the TR has been included in 
the general revision of the maintenance program, the general 
revision may be inserted into the maintenance requirements manual, 
provided the relevant information in the general revision is 
identical to that in the applicable TR, and the temporary revision 
may be removed.


    (2) After accomplishing the actions specified in paragraph 
(f)(1) of this AD, no alternative CDCCLs may be used unless the 
CDCCLs are part of a later revision of Bombardier Dash 8 Q400 MRM 
PSM 1-84-7, Revision 4, dated October 30, 2003, that is approved by 
the Manager, New York Aircraft Certification Office (ACO), FAA, or 
Transport Canada Civil Aviation (or its delegated agent); or unless 
the CDCCLs are approved as an alternative method of compliance 
(AMOC) in accordance with the procedures specified in paragraph 
(g)(1) of this AD.

FAA AD Differences


    Note 2: This AD differs from the MCAI and/or service information 
as follows: No differences.


Other FAA AD Provisions

    (g) The following provisions also apply to this AD:
    (1) Alternative Methods of Compliance (AMOCs): The Manager, New 
York Aircraft Certification Office, FAA, has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19. Send information to ATTN: Richard Fiesel, 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) 228-7304; fax (516) 794-
5531. Before using any approved AMOC on any airplane to which the 
AMOC applies, notify your appropriate principal inspector (PI) in 
the FAA Flight Standards District Office (FSDO), or lacking a PI, 
your local FSDO.
    (2) Airworthy Product: For any requirement in this AD to obtain 
corrective actions from a manufacturer or other source, use these 
actions if they are FAA-approved. Corrective actions are considered 
FAA-approved if they are approved by the State of Design Authority 
(or their delegated agent). You are required to assure the product 
is airworthy before it is returned to service.
    (3) Reporting Requirements: For any reporting requirement in 
this AD, under the provisions of the Paperwork Reduction Act, the 
Office of Management and Budget (OMB) has approved the information 
collection requirements and has assigned OMB Control Number 2120-
0056.

Related Information

    (h) Refer to MCAI Canadian Airworthiness Directive CF-2008-06, 
dated January 15, 2008; and Bombardier TRs ALI-55 and ALI-56, both 
dated April 19, 2006; for related information.

    Issued in Renton, Washington, on March 5, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E8-4771 Filed 3-10-08; 8:45 am]
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