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 Department of Transportation Federal Aviation Administration 14 CFR Part 39
[Docket No. FAA-2008-0147; Directorate Identifier 2007-NM-294-AD]
RIN 2120-AA64
 AGENCY: Federal Aviation Administration (FAA), Department of Transportation (DOT).
 ACTION: Notice of proposed rulemaking (NPRM).
 SUMMARY: The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain Boeing Model 737-600, -700, and -800 series airplanes. The existing AD currently requires repetitive inspections to detect damage of the aft strut insulation blanket, and eventual replacement of the insulation blankets with new, improved blankets. This proposed AD would add airplanes to the applicability and require installation of a new heat insulation blanket and new cover plate on the left and right side engine struts. This proposed AD would not retain the requirements of the existing AD and would terminate the requirements of the existing AD. This proposed AD results from reports of damaged heat insulation blankets on the engine struts. We are proposing this AD to prevent exposure of the lower surface of the strut to extreme high temperatures, consequent creation of a source of fuel ignition, and increased risk of an uncontrollable fire and possible fuel tank explosion.
 DATES: We must receive comments on this proposed AD by March 24, 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 W12-140, 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 AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. 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: Kathrine Rask, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue,  SW., Renton, Washington 98057-3356; telephone (425) 917-6505; fax (425) 917-6590.


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-2008-0147; Directorate Identifier 2007-NM-294-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 On February 4, 1999, we issued AD 99-04-11, amendment 39-11035 (64 FR 6791, February 11, 1999), for certain Boeing Model 737-600, -700, and -800 series airplanes. That AD requires repetitive inspections to detect damage of the aft strut insulation blanket. That AD also requires eventual replacement of the insulation blankets with new, improved blankets, which constitutes terminating action for the requirements of that AD. That AD resulted from reports of damaged aft strut insulation blankets. We issued that AD to prevent such damage, which could result in exposure of the lower surface of the strut to extreme high temperatures, consequent creation of a source of fuel ignition, and increased risk of an uncontrollable fire and possible fuel tank explosion. Actions Since Existing AD Was Issued Since we issued AD 99-04-11, we have received reports of failures of the insulation blankets that were installed in accordance with the requirements of that AD. A failed heat insulation blanket might go undetected in that area. Relevant Service Information We have reviewed Boeing Special Attention Service Bulletin 737-54-1045, dated July 25, 2007. The service bulletin describes procedures for installing a new heat insulation blanket, P/N S315A213-57, and a new cover plate on the left and right side engine struts. Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition. FAA's Determination and Requirements of the Proposed AD We have evaluated all pertinent information and identified an unsafe condition that is likely to develop on 
                    ( print page 7485)
                    other airplanes of the same type design. For this reason, we are proposing this AD, which would supersede AD 99-04-11 and require accomplishing the actions specified in the service bulletin described previously. This proposed AD would also add Model 737-700C and -900 series airplanes to the applicability. Costs of Compliance There are about 2,148 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 740 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this proposed AD. The average labor rate is $80 per work hour. Estimated Costs
Action
Work hours
Parts
Cost per 
                             airplane
Fleet costInstallation (new proposed action)
4
$4,730
$5,050
$3,737,000
 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. § 39.13
  2. The Federal Aviation Administration (FAA) amends § 39.13 by removing amendment 39-11035 (64 FR 6791, February 11, 1999) and adding the following new airworthiness directive (AD): **Boeing:**
                                 Docket No. FAA-2008-0147; Directorate Identifier 2007-NM-294-AD. Comments Due Date (a) The FAA must receive comments on this AD action by March 24, 2008. Affected ADs (b) This AD supersedes AD 99-04-11. Applicability (c) This AD applies to Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes, certificated in any category, as identified in Boeing Special Attention Service Bulletin 737-54-1045, dated July 25, 2007. Unsafe Condition (d) This AD results from reports of damaged heat insulation blankets on the engine struts. We are issuing this AD to prevent exposure of the lower surface of the strut to extreme high temperatures, consequent creation of a source of fuel ignition, and increased risk of uncontrollable fire and possible fuel tank explosion. 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. Installation (f) Within 60 months after the effective date of this AD, install a new heat insulation blanket, P/N S315A213-57, and a new cover plate on the left and right side engine struts in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-54-1045, dated July 25, 2007. Parts Installation (g) As of the effective date of this AD, no person may install a heat insulation blanket, P/N S315A213-42 or -47, on any airplane. Alternative Methods of Compliance (AMOCs) (h)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19. (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 appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.
 Issued in Renton, Washington, on January 31, 2008. Ali Bahrami, Manager, Transport Airplane Directorate, Aircraft Certification Service.


[FR Doc. E8-2351 Filed 2-7-08; 8:45 am] BILLING CODE 4910-13-P