Costs of Compliance

We estimate that this proposed AD would affect 160 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.
TableEstimated Costs Average labor Cost per Number of U.S.registered Action Work hours rate per hour product airplanes Fleet cost Inspections: Body skin and skin splice 1 $85 $85 160........................... $13,600. plate.
Modification: Groups 13 \1\........... 180 85 15,300 Up to 27...................... Up to $413,100. Modification: Groups 13 \2\........... 320 85 27,200 Up to 27...................... Up to $734,400. Modification: Groups 48 \3\........... 180 85 15,300 Up to 133..................... Up to $2,034,900. Modification: Groups 47 \4\........... 40 85 3,400 Up to 44...................... Up to $149,600. PostMod LFEC Inspection \5\........... 6 85 510 Up to 160..................... Up to $81,600. Inspections: Bulkhead Outer Chord \6\.. 4 85 340 Up to 160..................... Up to $54,400. \1\ Installation of skin and splice plate doubler for Groups 13 airplanes that have not done Boeing Service Bulletin 747532150 or Figure 35 of Section 533003 of the Boeing 747 Structural Repair Manual. \2\ Installation of skin and splice plate doubler for Groups 13 airplanes that have done Boeing Service Bulletin 747532150 or Figure 35 of Section 53 3003 of the Boeing 747 Structural Repair Manual.
\3\ Installation of skin and splice plate doubler for Groups 48 airplanes. \4\ Installation of splice plate doubler for Groups 47 airplanes changed before Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009.
\5\ Inspection for skin cracks around the fasteners at the periphery of the modification doublers. \6\ Includes inspection of the frame web and body skin.

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 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: The Boeing Company: Docket No. FAA20100674; Directorate Identifier 2010NM012AD.
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Comments Due Date
(a) We must receive comments by August 23, 2010.
Affected ADs
(b) None.
Applicability
(c) This AD applies to all The Boeing Company Model 747100, 747100B, 747100B SUD, 747200B, 747200C, 747200F, 747300, 747 400, 747400D, 747400F, 747SR, and 747SP series airplanes,
certificated in any category.
Subject
(d) Air Transport Association (ATA) of America Code 53: Fuselage.
Unsafe Condition
(e) This AD results from reports of cracking of the fuselage skin and adjacent internal skin splice plate at the left and right nose wheel well aft corners, and the outer chord of the body station (BS) 400 bulkhead. The Federal Aviation Administration is issuing this AD to detect and correct cracking of the fuselage skin or splice plate, which, together with cracking of the bulkhead outer chord, could result in large skin cracks and subsequent inflight rapid decompression 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.
PreModification Inspections
(g) For airplanes in Groups 1 through 3, as identified in Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009, that have not been modified in accordance with Boeing Service Bulletin 747532150; have not been repaired in accordance with Figure 35 of Section 533003 of Boeing 747 Structural Repair Manual (SRM); and have not been modified in accordance with Boeing Alert Service Bulletin 74753A2305: Before the accumulation of 3,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later, do an external detailed inspection for cracks in the body skin around the aft corners of the nose wheel well, and skin splice plate at the aft corners of the nose wheel well, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009.
(h) For airplanes in Groups 1 through 3, as identified in Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009, that have been modified in accordance with Boeing Service Bulletin 747532150; or repaired in accordance with Boeing 747 Figure 35 of Section 533003 of Boeing 747 SRM: Within 6,000 flight cycles after doing the modification or repair, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later, do an external detailed inspection for cracks in the body skin around the aft corners of the nose wheel well, and skin splice plate at the aft corners of the nose wheel well, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009.
(i) For airplanes in Groups 4 through 7, as identified in Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009, that have not been modified in accordance with Boeing Alert Service Bulletin 74753A2305: Prior to the accumulation of 3,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later, do an external detailed inspection for cracks in the body skin around the aft corners of the nose wheel well, in accordance with the
Accomplishment Instructions of Boeing Alert Service Bulletin 747 53A2305, Revision 2, dated January 15, 2009.
(j) For airplanes in Groups 4 through 7, as identified in Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009, that have been modified in accordance with Boeing Service Bulletin 747532305, dated June 27, 1991; or Revision 1, dated May 22, 1997: Within 1,000 flight cycles after the effective date of this AD, do a onetime external general visual inspection for steel crossshaped doublers, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009. If no crossshaped doublers are
installed, within 1,500 flight cycles after the effective date of this AD, install crossshaped doublers, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747 53A2305, Revision 2, dated January 15, 2009.
(k) For airplanes in Group 8, as identified in Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009: Prior to the accumulation of 3,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later, do an external detailed inspection for cracks in the body skin around the aft corners of the nose wheel well, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009. (l) If no crack is found during any inspection required by paragraph (g), (h), (i), or (k) of this AD, repeat the applicable inspection specified in paragraph (g), (h), (i), or (k) of this AD thereafter at intervals not to exceed 1,500 flight cycles, until the modification specified in paragraph (n) of this AD is accomplished. (m) If any crack is found during any inspection required by paragraph (g), (h), (i), (k), or (l) of this AD, before further flight, modify the aft corners of the nose wheel well by installing modification doublers and doing all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009, except as required by paragraph (t) of this AD.
Optional Terminating Action
(n) Modification of the aft corners of the nose wheel well by installing modification doublers and doing all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747 53A2305, Revision 2, dated January 15, 2009, terminates the repetitive inspections required by paragraph (l) of this AD for the modified side only. Where Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009, specifies to contact Boeing for appropriate action, repair using a method approved in accordance with the procedures specified in paragraph (u) of this AD.
PostModification Repetitive Inspections
(o) For airplanes on which the modification specified in Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009, has been done: At the applicable time specified in paragraph (o)(1) or (o)(2) of this AD, do an external low frequency eddy current inspection for skin cracks around the fasteners at the periphery of the modification doublers, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747 53A2305, Revision 2, dated January 15, 2009.
(1) For airplanes on which the edge row fastener holes common to the external modification doublers have been zerotimed in
accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009: Within 15,000 flight cycles after accomplishing the modification, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later.
(2) For airplanes on which the edge row fastener holes common to the external modification doublers have not been zerotimed in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009: Prior to the accumulation of 15,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later.
(p) If no cracking is found during the inspection required by paragraph (o) of this AD, repeat the inspection specified in paragraph (o) of this AD thereafter at intervals not to exceed 1,500 flight cycles.
(q) If any cracking is found during any inspection required by paragraph (o) or (p) of this AD, before further flight, repair using a method approved in accordance with the procedures specified in paragraph (u) of this AD.
Body Station (BS) 400 Bulkhead Outer Chord Inspection
(r) For all airplanes: At the latest of the times specified in paragraphs (r)(1), (r)(2), and (r)(3) of this AD, do a surface HFEC for cracking in the BS 400 bulkhead outer chord, skin splice plate, and outer chord radius filler; and a detailed inspection for cracking of the bulkhead frame web and body skin; in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009. If no cracking is found during any inspection, repeat the inspection one time within 6,000 flight cycles, and thereafter at intervals not to exceed 3,000 flight cycles.
(1) Before the accumulation of 20,000 total flight cycles. (2) Within 3,000 flight cycles after doing the HFEC inspection required by AD 2004
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0722 R1, Amendment 3915326, for structural significant item (SSI) F4B of the Boeing Document No. D635022, ``Supplemental Structural Inspection Document (SSID) for Model 747 Airplanes,'' Revision G, dated December 2000.
(3) Within 1,500 flight cycles after the effective date of this AD.
(s) If any cracking is found during any inspection required by paragraph (r) of this AD, before further flight, repair in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009, except as required by paragraph (t) of this AD. Within 6,000 flight cycles after doing the repair, do the inspections specified in paragraph (r) of this AD, and repeat the inspections thereafter at intervals not to exceed 3,000 flight cycles.
Service Bulletin Exception
(t) If any cracking is found during any inspection required by this AD, and Boeing Alert Service Bulletin 74753A2305, Revision 2, dated January 15, 2009, 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 (u) of this AD.
Alternative Methods of Compliance (AMOCs)
(u)(1) The Manager, Seattle 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

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.