We have revised paragraph (g) of AD 20041609 to allow repairs in accordance with data that conforms to an airplane's type certificate and that are approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization whom we have authorized to make such findings.

Change to Existing AD

This proposed AD would retain all requirements of AD 20041609. Since AD 20041609 was issued, the AD format has been revised, and certain paragraphs have been rearranged. As a result, the corresponding paragraph identifiers have changed in this proposed AD, as listed in the following table:
Revised Paragraph Identifiers
Corresponding requirement in Requirement in AD 20041609 this proposed AD paragraph (a)............................. paragraph (f).
paragraph (b)............................. paragraph (g).
paragraph (c)............................. paragraph (h).
paragraph (d)............................. paragraph (i).
paragraph (e)............................. paragraph (j).
paragraph (f)............................. paragraph (k).

paragraph (g)............................. paragraph (l).

The cost information specified in AD 20041609 inadvertently contained information on oncondition inspections. The cost information, below, has been revised to state only the work hours necessary for the initial and repetitive inspections specified in paragraph (g) of this proposed AD.

Costs of Compliance

There are about 917 airplanes of the affected design in the worldwide fleet.
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This proposed AD would affect about 165 airplanes of U.S. registry.

The actions that are required by AD 20041609 and retained in this proposed AD take about 2 work hours per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the currently required actions to the U.S. operators is $26,400, or $160 per airplane, per inspection cycle.

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 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 Federal Aviation Administration (FAA) amends Sec. 39.13 by removing amendment 3913765 (69 FR 48133, August 9, 2004) and adding the following new airworthiness directive (AD):
Boeing: Docket No. FAA20080731; Directorate Identifier 2008NM 058AD.
Comments Due Date
(a) The FAA must receive comments on this AD action by August 18, 2008.
Affected ADs
(b) This AD supersedes AD 20041609.
Applicability
(c) This AD applies to all Boeing Model 747100, 747100B, 747 100B SUD, 747200B, 747200C, 747200F, 747300, 747400, 747400D, 747400F, 747SR, and 747SP series airplanes, certificated in any category.
Unsafe Condition
(d) This AD results from a report that cracks in oilcanned areas were found during an inspection of the aft pressure bulkhead. We are issuing this AD to detect and correct the propagation of fatigue cracks in the vicinity of oil cans on the web of the aft pressure bulkhead, which could result in rapid decompression of the airplane and overpressurization of the tail section, and consequent loss of control of the airplane.
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.

Note 1: This AD refers to certain portions of a Boeing service bulletin for inspections and repair information. In addition, this AD specifies requirements beyond those included in the service bulletin. Where the AD and the service bulletin differ, the AD prevails.
Service Bulletin References
(f) The term ``service bulletin,'' as used in this AD, means the Accomplishment Instructions of Boeing Alert Service Bulletin 747 53A2482, dated October 3, 2002; or Boeing Alert Service Bulletin 74753A2482, Revision 1, dated February 21, 2008. After the effective date of this AD, Revision 1 must be used.
Requirements of AD 20041609, With Reduced Threshold
Initial and Repetitive Inspections
(g) At the earlier of the times specified in paragraphs (g)(1) and (g)(2) of this AD, perform a detailed inspection of the aft pressure bulkhead for indications of oil cans and previous oil can repairs, in accordance with the service bulletin.
(1) Prior to the accumulation of 30,000 total flight cycles, or within 1,000 flight cycles after September 13, 2004 (the effective date of AD 20041609), whichever is later.
(2) Prior to the accumulation of 20,000 total flight cycles, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later.

Note 2: For the purposes of this AD, a detailed inspection is ``an intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirrors, magnifying lenses, etc. may be necessary. Surface cleaning and elaborate procedures may be required.''
(h) If no indication of an oil can is found and no indication of a previous oil can repair is found during the detailed inspection required by paragraph (g) of this AD, repeat the detailed inspection thereafter at intervals not to exceed 2,000 flight cycles.
Indication of Oil Can
(i) If any indication of an oil can is found during the detailed inspection required by paragraph (g) or (h) of this AD, before further flight, perform an eddy current inspection of the web around the periphery of the oil can indication for cracks, as shown in Figure 3 of the service bulletin.
(j) If no crack is found during the eddy current inspection required by paragraph (i) of this AD, do the actions specified in paragraph (j)(1) or (j)(2) of this AD, as applicable.
(1) For the oil can that meets the allowable limits specified in the service bulletin: Repeat the eddy current inspection specified in paragraph (i) of this AD thereafter at intervals not to exceed 1,000 flight cycles. As an option, repair the oil can in accordance with paragraph (j)(2) of this AD.
(2) For the oil can that does not meet the allowable limits specified in the service bulletin: Before further flight, repair the oil can in accordance with the service bulletin. If the repair eliminates the oil can, accomplishment of this repair constitutes terminating action for the repetitive eddy current inspection requirements of paragraph (j)(1) of this AD for that location only. However, the repetitive detailed inspection required by paragraph (h) of this AD is still required. If any oil can remains after the repair, repeat the eddy current inspection specified in paragraph (i) of this AD thereafter at intervals not to exceed 1,000 flight cycles.
[[Page 37903]]
Indication of Previous Oil Can Repairs
(k) If any previous oil can repair is found during the detailed inspection required by paragraph (g) or (h) of this AD, before further flight, do a detailed inspection of the web for cracks and oil cans, as shown in Figure 4 or Figure 5 of the service bulletin, as applicable.
(1) If no crack and no oil can are found, repeat the detailed inspection in accordance with paragraph (h) of this AD.
(2) If any oil can is found, before further flight, do the eddy current inspection for cracks, as shown in Figure 3 of the service bulletin. If no crack is found during the eddy current inspection required by this paragraph, do the actions specified in paragraph (j)(1) or (j)(2) of this AD, as applicable, at the time specified in the applicable paragraph.
Repair of Cracks
(l) If any crack is found during any inspection required by this AD, before further flight, repair in accordance with the service bulletin. If any crack or damage exceeds limits specified in the service bulletin and the service bulletin specifies to contact Boeing for appropriate action: Before further flight, repair per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings; or using a method approved in accordance with the procedures specified in paragraph (n) of this AD. For a repair method to be approved, the approval must specifically reference this AD.
New Requirements of This AD
(m) As of the effective date of this AD, if any crack or damage is found during any inspection required by this AD, and Boeing Alert Service Bulletin 74753A2482, Revision 1, dated February 21, 2008, specifies to contact Boeing for appropriate action (repair data): Before further flight, repair the crack or damage using a method approved in accordance with the procedures specified in paragraph (n) of this AD.
Alternative Methods of Compliance (AMOCs)
(n)(1) The Manager, Seattle Aircraft Certification Office, 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.
(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.
(4) AMOCs approved previously in accordance with AD 20041609 are not approved as AMOCs for the corresponding provisions of paragraph (g) of this AD. They are approved as AMOCs for the corresponding provisions of paragraphs (h), (i), (j), (k), (l), and (m) of this AD.

Issued in Renton, Washington, on June 24, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. E814974 Filed 7108; 8:45 am]
BILLING CODE 491013P

FOR FURTHER INFORMATION CONTACT Ivan Li, Aerospace Engineer, Airframe Branch, ANM120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 980573356; telephone (425) 9176437; fax (425) 9176590.