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 Department of Transportation Federal Aviation Administration 14 CFR Part 39
[Docket No. FAA-2009-0213; Directorate Identifier 2008-NM-224-AD]
RIN 2120-AA64
 AGENCY: Federal Aviation Administration (FAA), DOT.
 ACTION: Notice of proposed rulemaking (NPRM).
 SUMMARY: We propose to adopt a new airworthiness directive (AD) for certain McDonnell Douglas Model MD-90-30 airplanes. This proposed AD would require installing fuses and wire protection in certain wing and fuel tank spars. This proposed AD results from fuel system reviews conducted by the manufacturer. We are proposing this AD to prevent possible damage to the fuel level float or pressure switch wires. Such damage could become a potential ignition source inside the fuel tank, and, combined with flammable fuel vapors, could result in a fuel tank explosion and consequent loss of the airplane.
 DATES: We must receive comments on this proposed AD by April 24, 2009.
 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 W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. For service information identified in this proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, 3855 Lakewood Boulevard, MC D800-0019, Long Beach, California 90846-0001; telephone 206-544-5000, extension 2; fax 206-766-5683; e-mail 
                        *dse.boecom@boeing.com;*
                         Internet 
                        *https://www.myboeingfleet.com.*
                         You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221 or 425-227-1152. Examining the AD Docket You may examine the AD docket on the Internet at 
                    *http://www.regulations.gov*; or in person at the Docket Management Facility 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 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: Samuel Lee, Aerospace Engineer, Propulsion Branch, ANM-140L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5262; fax (562) 627-5210.


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-2009-0213; Directorate Identifier 2008-NM-224-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 because of 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 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” (67 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 another 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 a fuel tank explosion and consequent loss of the airplane. We have received a report that fuel level float switch wires located on the left and right wing forward spar, center fuel tank forward spar and forward auxiliary fuel tank, and pressure switch wires located on the center fuel tank forward spar are routed in the same bundles as power wires. If a short circuit between a fuel level float or pressure switch wire and a power wire occurs, an over current can cause excessive temperatures in the fuel level float or pressure switch wires, resulting in damage and becoming a potential ignition source. This condition, if not corrected, could result in possible damage to the fuel level float or pressure switch wires, and become a potential ignition source for the fuel tank. Relevant Service Information We have reviewed Boeing Service Bulletin MD90-28-012, dated November 19, 2008. The service bulletin describes procedures for installing fuses and wire protection in certain wing and fuel tank spars. For Group 1, the service bulletin describes procedures for installing fuel level float switch in-line fuses and wire protection in the left and right wing forward spars and center fuel tank forward spar, right side. For Group 2, the service bulletin describes procedures for installing fuel level float switch in-line fuses and wire protection in the left and right wing forward spars, center fuel tank forward spar, right side, and forward auxiliary fuel tank, right side; and installing a fuel pressure switch in-line fuse and wire protection in the center fuel tank forward spar, left side. FAA's Determination and Requirements of This Proposed AD We are proposing this AD because we evaluated all relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the(se) same type design(s). This proposed AD would require accomplishing the 
                    ( print page 10204)
                    actions specified in the service information described previously. Costs of Compliance We estimate that this proposed AD would affect 15 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this proposed AD. Table—Estimated Costs
Action
Work hours
Average labor rate per hour
Parts
Cost per product
Number of U.S.-registered airplanes
Fleet costInstallation, depending on Group
20 or 26
$80
$1,132 or $1,822
$2,732 or $3,902
15
$40,980 to $58,530.
 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. You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket. List of Subjects in 14 CFR Part 39 Air transportation
Aircraft
Aviation safety
Incorporation by reference
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. § 39.13
  2. The FAA amends § 39.13 by adding the following new AD: **McDonnell Douglas:**
                                 Docket No. FAA-2009-0213; Directorate Identifier 2008-NM-224-AD. Comments Due Date (a) We must receive comments by April 24, 2009. Affected ADs (b) None. Applicability (c) This AD applies to McDonnell Douglas Model MD-90-30 airplanes, certificated in any category, excluding fuselage number 2159. Subject (d) Air Transport Association (ATA) of America Code 28: Fuel. Unsafe Condition (e) This AD results from fuel system reviews conducted by the manufacturer. We are issuing this AD to prevent possible damage to the fuel level float or pressure switch wires. Such damage could become a potential ignition source inside the fuel tank, and, when combined with flammable fuel vapors, could result in a fuel tank explosion and consequent loss of the airplane. Compliance (f) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done. Installation (g) Within 5 years after the effective date of this AD, do the actions specified in paragraph (g)(1) or (g)(2) of this AD, as applicable, in accordance with the Accomplishment Instructions of Boeing Service Bulletin MD90-28-012, dated November 19, 2008 (“the service bulletin”). (1) For Group 1 airplanes identified in the service bulletin, install fuel level float switch in-line fuses and wire protection in the left and right wing forward spars and center fuel tank forward spar, right side. (2) For Group 2 airplanes identified in the service bulletin, install fuel level float switch in-line fuses and wire protection in the left and right wing forward spars, center fuel tank forward spar, right side, and forward auxiliary fuel tank, right side; and install a fuel pressure switch in-line fuse and wire protection in the center fuel tank forward spar, left side. Alternative Methods of Compliance (AMOCs) (h)(1) The Manager, Los Angeles 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:*
                                 Samuel Lee, Aerospace Engineer, Propulsion Branch, ANM-140L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5262; fax (562) 627-5210. (2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, or lacking a principal inspector, your local Flight Standards District Office. The AMOC approval letter must specifically reference this AD.
 Issued in Renton, Washington, on February 27, 2009. Ali Bahrami, Manager, Transport Airplane Directorate, Aircraft Certification Service.


[FR Doc. E9-5014 Filed 3-9-09; 8:45 am] BILLING CODE 4910-13-P