
[Federal Register: September 23, 2008 (Volume 73, Number 185)]
[Proposed Rules]               
[Page 54749-54751]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr23se08-29]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-1007; Directorate Identifier 2008-NM-135-AD]
RIN 2120-AA64

 
Airworthiness Directives; Bombardier Model CL-600-2C10 (Regional 
Jet Series 700, 701 & 702) Airplanes and Model CL-600-2D24 (Regional 
Jet Series 900) Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

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 CL-600-2C10/CL-600-2D24 aircraft fuel system against new fuel 
tank safety standards. The assessment showed that due to the close 
proximity of intrinsically safe fuel system wiring with other wiring, a 
single failure from wire chafing at various locations of the fuselage 
could result in an ignition source inside the fuel tank. In addition, 
chafing of the temperature sensor wiring against the high power wiring 
in the avionics compartment could lead to overheating of the 
temperature sensor and hot surface ignition. The presence of an 
ignition source inside the fuel tank 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 October 23, 
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: Rocco Viselli, 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) 228-7331; 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-2008-1007; 
Directorate Identifier 2008-NM-135-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-
2008-25, dated July 3, 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 
CL-600-2C10/CL-600-2D24 aircraft fuel system against new 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 assessed using Transport Canada 
Policy Letter No. 525-001 to determine if mandatory corrective 
action was required.
    The assessment showed that due to the close proximity of 
intrinsically safe fuel system wiring with other wiring, a single 
failure from wire chafing at various locations of the fuselage could 
result in an ignition source inside the fuel tank. In addition, 
chafing of the temperature sensor wiring against the high power 
wiring in the avionics compartment could lead to overheating of the 
temperature sensor and hot surface ignition. The presence of an 
ignition source inside the fuel tank could result in a fuel tank 
explosion.
    To correct the unsafe condition, this directive mandates the 
installation of conduit and the addition of spacers to protect fuel 
tank wiring.

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

[[Page 54750]]

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 
in fuel tank explosions and consequent loss of the airplane.

Relevant Service Information

    Bombardier has issued Service Bulletin 670BA-24-011, Revision C, 
dated November 28, 2005. 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.

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 159 products of U.S. registry. We also estimate that 
it would take about 38 work-hours per product to comply with the basic 
requirements of this proposed AD. The average labor rate is $80 per 
work-hour. Required parts would cost about $2,914 per product. Where 
the service information lists required parts costs that are covered 
under warranty, we have assumed that there will be no charge for these 
costs. As we do not control warranty coverage for affected parties, 
some parties may incur costs higher than estimated here. Based on these 
figures, we estimate the cost of the proposed AD on U.S. operators to 
be $946,686, or $5,954 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 Canadair): Docket No. FAA-2008-1007; 
Directorate Identifier 2008-NM-135-AD.

Comments Due Date

    (a) We must receive comments by October 23, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to the airplanes identified in paragraphs 
(c)(1) and (c)(2) of this AD, certificated in any category.
    (1) Bombardier Model CL-600-2C10 (Regional Jet Series 700, 701, 
& 702) airplanes, serial numbers 10003 through 10169 inclusive.
    (2) Bombardier Model CL-600-2D24 (Regional Jet Series 900) 
airplanes, serial numbers 15001 through 15030 inclusive.

Subject

    (d) Air Transport Association (ATA) of America Code 24: 
Electrical Power.

Reason

    (e) The mandatory continuing airworthiness information (MCAI) 
states:
    Bombardier Aerospace has completed a system safety review of the 
CL-600-2C10/CL-600-2D24 aircraft fuel system against new fuel tank 
safety standards, introduced in Chapter 525 of the Airworthiness 
Manual through Notice of Proposed Amendment

[[Page 54751]]

(NPA) 2002-043. The identified non-compliances were assessed using 
Transport Canada Policy Letter No. 525-001 to determine if mandatory 
corrective action was required.
    The assessment showed that due to the close proximity of 
intrinsically safe fuel system wiring with other wiring, a single 
failure from wire chafing at various locations of the fuselage could 
result in an ignition source inside the fuel tank. In addition, 
chafing of the temperature sensor wiring against the high power 
wiring in the avionics compartment could lead to overheating of the 
temperature sensor and hot surface ignition. The presence of an 
ignition source inside the fuel tank could result in a fuel tank 
explosion.
    To correct the unsafe condition, this directive mandates the 
installation of conduit and the addition of spacers to protect fuel 
tank wiring.

Actions and Compliance

    (f) Unless already done, do the following actions.
    (1) Within 4,500 flight hours after the effective date of this 
AD, modify the fuel system wiring along the fuselage and in the 
avionics compartment by installing protective conduit and spacers, 
in accordance with the Accomplishment Instructions of Bombardier 
Service Bulletin 670BA-24-011, Revision C, dated November 28, 2005.
    (2) Actions done before the effective date of this AD in 
accordance with Bombardier Service Bulletin 670BA-24-011, dated 
September 7, 2004; Revision A, dated December 14, 2004; or Revision 
B, dated February 28, 2005; are acceptable for compliance with the 
corresponding requirements of this AD.

FAA AD Differences

    Note: 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 (ACO), 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: Rocco Viselli, Aerospace 
Engineer, Airframe and Propulsion Branch, ANE-171, FAA, New York 
ACO, 1600 Stewart Avenue, Suite 410, Westbury, New York 11590; 
telephone (516) 228-7331; 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-2008-25, 
dated July 3, 2008, and Bombardier Service Bulletin 670BA-24-011, 
Revision C, dated November 28, 2005, for related information.

    Issued in Renton, Washington, on September 12, 2008.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E8-22218 Filed 9-22-08; 8:45 am]

BILLING CODE 4910-13-P
