We estimate that this proposed AD would affect 17 airplanes of U.S. registry. We also estimate that it would take 7 workhours per product to comply with this proposed AD. The average labor rate is $80 per workhour. Based on these figures, we estimate the cost of this proposed AD to the U.S. operators to be $9,520, or $560 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.

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, 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 39AIRWORTHINESS 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: Boeing: Docket No. FAA20080669; Directorate Identifier 2007NM 350AD.
Comments Due Date
(a) We must receive comments by August 8, 2008.
Affected ADs
(b) None.
Applicability
(c) This AD applies to Boeing Model 737600, 700, and 800 series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 73757A1294, dated April 23, 2007. Unsafe Condition
(d) This proposed AD results from drill starts being found on the free flange of the lower stringers of the wing center during a quality assurance inspection at the final assembly plant. We are proposing this AD to prevent cracks from propagating from drill starts in the free flange of the wing center section lower stringers, which could cause a loss of structural integrity of the wing center section and may result in a fuel leak.
Compliance
(e) Comply with this AD within the compliance times specified, unless already done.
Inspection and Related Investigative and Corrective Actions (f) Before the accumulation of 18,000 total flight cycles, or within 90 days after the effective date of this AD, whichever occurs later, do a detailed inspection of the free flange of the lower stringers of the wing center section for any drill start, and do any applicable related investigative and corrective actions, by accomplishing all the applicable actions specified in paragraphs 3.B.2. and 3.B.4. of the Accomplishment Instructions of the Boeing Alert Service Bulletin 73757A1294, dated April 23, 2007; except as provided in paragraph (g) of this AD. The applicable related investigative and corrective actions must be done before further flight.
(g) If any crack is found during any inspection required by paragraph (f) of this AD, and Boeing Alert Service Bulletin 737 57A1294, dated April 23, 2007, specifies to contact Boeing for appropriate action: Before further flight, repair the crack using a method approved in accordance with the procedures specified in paragraph (h) of this AD.
Alternative Methods of Compliance (AMOCs)
(h)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, ATTN: Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM 120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 980573356; telephone (425) 9176440, fax (425) 9176590 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.
(3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane.

Issued in Renton, Washington, on June 12, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. E814185 Filed 62308; 8:45 am]
BILLING CODE 491013P

FOR FURTHER INFORMATION CONTACT Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 980573356, telephone (425) 9176440; fax (425) 9176590.