AD 2006-08-02

You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

At the earliest of the times specified in paragraphs (f)(1) through (f)(3) of this AD, do the inspection required by paragraph (g) of this AD.

(1) Before the accumulation of 22,000 total flight cycles, or within 1,000 flight cycles after March 15, 2004 (the effective date of AD 2004-03-11), whichever occurs later.

(2) For airplanes with 17,000 or more total flight cycles as of the effective date of this AD: Before the accumulation of 18,000 total flight cycles, or within 90 days after the effective date of this AD, whichever occurs later.

(3) For airplanes with fewer than 17,000 total flight cycles as of the effective date of this AD: Before the accumulation of 15,000 total flight cycles, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later.

Do the applicable inspection to find fatigue cracking in the upper chord of the upper deck floor beams as specified in Part 1 (Open-Hole High Frequency Eddy Current (HFEC) Inspection Method) or Part 2 (Surface HFEC Inspection Method) of the Work Instructions of Boeing Alert Service Bulletin 747-53A2439, dated July 5, 2001. Do the inspections per the service bulletin, except as provided by paragraph (j) of this AD. Any combination of the applicable inspection methods specified in Parts 1 and 2 may be used, provided that the corresponding repetitive inspection interval is used.

(1) If any crack is found, before further flight, repair per Part 3 (Upper Chord Repair) of the Work Instructions of the service bulletin; except where the service bulletin specifies to contact Boeing for appropriate action, before further flight, repair according to a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or according to data meeting the certification basis of the airplane approved by an a Boeing Company Designated Engineering Representative (DER) or Authorized Representative for the Boeing Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically reference this AD. Do the applicable inspection of the repaired area per Part 1 of the Work Instructions of the service bulletin at the applicable time per Part 3 of the Work Instructions of the service bulletin, and repeat the applicable inspection at the applicable interval per Figure 1 of the service bulletin.

(2) If no crack is found, repeat the applicable inspection per paragraph (g) of this AD at the applicable time specified in paragraphs (g)(2)(i) through (g)(2)(iii) of this AD. As an option to the repetitive inspections, accomplishment of paragraph (h)(1) or (h)(2) of this AD, before further flight, extends the threshold for the initiation of the repetitive inspections required by this paragraph.

(i) If the immediately preceding inspection was conducted using an open-hole HFEC inspection method: Conduct the next inspection of that area within 3,000 flight cycles of the last inspection.

(ii) If the immediately preceding inspection was conducted using a surface HFEC inspection method at stations 340 through 420 inclusive and station 500: Conduct the next inspection of that area within 750 flight cycles of the last inspection.

(iii) If the immediately preceding inspection was conducted using a surface HFEC inspection method at stations 440 and 520: Conduct the next inspection of that area at the earlier of the times specified in paragraphs (g)(2)(iii)(A) and (g)(2)(iii)(B) of this AD, and thereafter at intervals not to exceed 250 flight cycles.

(A) Within 750 flight cycles since the last surface HFEC inspection required by paragraph (g) of this AD.

(B) Within 250 flight cycles after the effective date of this AD.

For areas on which the inspection required by paragraph (g) of this AD is done per Part 1 of the Work Instructions of Boeing Alert Service Bulletin 747-53A2439, dated July 5, 2001, or Revision 1, dated March 10, 2005; and on which no cracking is found: Accomplishment of the actions specified in either paragraph (h)(1) or (h)(2) of this AD extends the threshold for the initiation of the repetitive inspections required by paragraph (g)(2) of this AD. For areas on which the inspection required by paragraph (g) of this AD is done per Part 2 of the Work Instructions of Boeing Alert Service Bulletin 747-53A2439, dated July 5, 2001, or Revision 1, dated March 10, 2005; and on which no cracking is found: Accomplishment of the actions specified in paragraph (h)(1) of this AD extends the threshold for the initiation of the repetitive inspections required by paragraph (g)(2) of this AD.

(1) Do the applicable repair per Part 3 of the Work Instructions of the service bulletin, except as provided by paragraph (j) of this AD. At the applicable time specified in Table 1 of Part 3 of the Work Instructions of the service bulletin, do the applicable inspection of the repaired area per Part 1 of the Work Instructions of the service bulletin. Repeat the inspection thereafter within the applicable interval of 3,000 flight cycles per Figure 1 of the service bulletin.

(2) Do the modification of the attachment hole of the floor panel per Figure 5 of the service bulletin, except as provided by paragraph (j) of this AD. Within 10,000 flight cycles after accomplishment of the modification, do the inspection of the modified area per Part 1 of the Work Instructions of the service bulletin. Repeat the inspection thereafter within the applicable interval of 3,000 flight cycles per Figure 1 of the service bulletin.

(i) For the purposes of calculating the compliance threshold and repetitive intervals for actions required by paragraphs (f), (g), or (h) of this AD: As of the effective date of this AD, all flight cycles, including the number of flight cycles in which cabin differential pressure is at 2.0 pounds per square inch (psi) or less, must be counted when determining the number of flight cycles that have occurred on the airplane.

As of the effective date of this AD, use only the service bulletin specified in Table 1 of this AD.

Although the service bulletin referenced in this AD specifies to submit certain information to the manufacturer, this AD does not include that requirement.