[Federal Register Volume 71, Number 70 (Wednesday, April 12, 2006)]
[Rules and Regulations]
[Pages 18618-18623]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-3432]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-22423; Directorate Identifier 2005-NM-068-AD; 
Amendment 39-14556; AD 2006-08-02]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-200C and -200F Series 
Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: The FAA is superseding an existing airworthiness directive 
(AD), which applies to certain Boeing Model 747-200C and -200F series 
airplanes. That AD currently requires repetitive inspections to find 
fatigue cracking in the upper chord of the upper deck floor beams, and 
repair if necessary. For certain airplanes, the existing AD also 
provides an optional repair/modification, which extends certain 
repetitive inspection intervals. This new AD reduces the compliance 
time for all initial inspections and reduces the repetitive interval 
for a certain inspection. This AD results from new reports of cracks in 
the upper deck floor beams occurring at lower flight cycles. We are 
issuing this AD to find and fix cracking in certain upper deck floor 
beams. Such cracking could extend and sever floor beams at a floor 
panel attachment hole location and could result in rapid decompression 
and loss of controllability of the airplane.

DATES: This AD becomes effective May 17, 2006.
    The Director of the Federal Register approved the incorporation by 
reference of Boeing Alert Service Bulletin 747-53A2439, Revision 1, 
dated March 10, 2005, as listed in the AD as of May 17, 2006.
    On March 15, 2004 (69 FR 5920, February 9, 2004), the Director of 
the Federal Register approved the incorporation by reference of Boeing 
Alert Service Bulletin 747-53A2439, dated July 5, 2001.

ADDRESSES: You may examine the AD docket on the Internet at http://dms.dot.gov or in person at the Docket Management Facility, U.S. 
Department of Transportation, 400 Seventh Street, SW., Nassif Building, 
Room PL-401, Washington, DC.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for service information identified in this AD.

FOR FURTHER INFORMATION CONTACT: Ivan Li, Aerospace Engineer, Airframe 
Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind 
Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6437; 
fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Examining the Docket

    You may examine the airworthiness directive (AD) docket on the 
Internet at http://dms.dot.gov or in person at the Docket Management 
Facility office between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. The Docket Management Facility office 
(telephone (800) 647-5227) is located on the plaza level of the Nassif 
Building at the street address stated in the ADDRESSES section.

Discussion

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 to include an AD that supersedes AD 2004-03-11, amendment 
39-13455 (69 FR 5920, February 9, 2004). The existing AD applies to 
certain Boeing Model 747-200C and -200F series airplanes. That NPRM was 
published in the Federal Register on September 16, 2005 (70 FR 54668). 
That

[[Page 18619]]

NPRM proposed to require repetitive inspections to find fatigue 
cracking in the upper chord of the upper deck floor beams, and repair 
if necessary. For certain airplanes, the NPRM also proposed an optional 
repair/modification, which extends certain repetitive inspection 
intervals.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments that have been 
received on the NPRM.

Request To Revise Initial Inspection Threshold for Certain Airplanes

    For airplanes that have accumulated 17,000 or more total flight 
cycles, the Air Transport Association (ATA) on behalf of one of its 
members, Northwest Airlines, requests that we revise the grace period 
for the initial inspection threshold specified in paragraph (f)(2) of 
the NPRM from 90 days to 500 flight cycles. They state that this change 
would implement a definitive inspection limit to more accurately 
measure fatigue-related concerns and would align with operators' 
regularly scheduled heavy maintenance check.
    We partially agree. We agree with ATA and Northwest Airlines that 
cracking of the affected upper deck floor beams is attributed to 
fatigue, and that a compliance time based on flight cycles is 
appropriate for inspecting for fatigue cracking. However, we do not 
agree with their request to revise the grace period for the inspections 
required by this AD. In developing an appropriate compliance time for 
this AD, we considered the safety implications, the airplane 
manufacturer's recommended compliance time, and normal maintenance 
schedules for the timely accomplishment of the inspections and repair 
if necessary. In consideration of these items, as well as the reports 
of significant cracking at the affected floor beams on airplanes that 
had accumulated as low as 19,580 total flight cycles, we have 
determined that the 90-day grace period specified in paragraph (f)(2) 
of this AD is appropriate. For high-cycle airplanes that have 
accumulated 17,000 or more total flight cycles as of the effective date 
of this AD, the 90-day grace period is merely a time that we provide 
the operators to plan for the necessary actions and to avoid immediate 
grounding of airplanes. This grace period will ensure an acceptable 
level of safety and will allow the required inspections to be done 
during scheduled maintenance intervals for most affected operators. 
However, under the provisions of paragraph (l) of the AD, we may 
approve requests for adjustments to the compliance time if data are 
submitted to substantiate that such an adjustment would provide an 
acceptable level of safety. Therefore, we find that no change to the 
final rule is necessary in this regard.

Request To Clearly Distinguish the Old and New Requirements

    Boeing requests that we revise paragraphs (g)(1), (h)(1), and 
(h)(2) of the NPRM to more clearly distinguish between the old and new 
requirements. They state that those paragraphs specify requirements 
from AD 2004-03-11, as well as new requirements. They believe that this 
could cause operators to be confused as to which requirements to comply 
with. They also state that paragraphs (f) through (k) of the NPRM are 
under a header titled, ``REQUIREMENTS OF AD 2004-03-11,'' which would 
imply that those paragraphs have no new information.
    We agree. For clarification purposes, we have revised the AD as 
follows:
     Revised the header ``REQUIREMENTS OF AD 2004-03-11'' to 
``RESTATEMENT OF REQUIREMENTS OF AD 2004-03-11, BUT WITH A NEW REDUCED 
THRESHOLD AND REDUCED REPETITIVE INTERVALS FOR CERTAIN FLOOR BEAMS'';
     Added a new header, ``NEW REQUIREMENTS OF THIS AD'';
     Moved paragraphs (i) and (j) of the NPRM under the new 
header and reidentified paragraph (j) as paragraph (k);
     Moved the sentences in paragraphs (g), (g)(1), and (h)(1) 
that require operators to do the required actions, as of the effective 
date of this AD, in accordance with Boeing Alert Service Bulletin 747-
53A2439, Revision 1, dated March 10, 2005; to new paragraph (j), ``New 
Revision of Service Bulletin,'' in the AD; and
     Clarified in paragraphs (h)(1) and (h)(2) that the 
repetitive inspection interval is 3,000 flight cycles, as shown in 
Figure 1 of the service bulletin.

Request To Delete Reference to Part 1 of the Service Bulletin in 
Paragraphs (g)(1) and (h)(1)

    Boeing also requests that we delete the reference to ``Part 1'' of 
the Work Instructions of Boeing Alert Service Bulletin 747-53A2439, 
Revision 1, dated March 10, 2005, in the last sentence of paragraph 
(g)(1) and in the second sentence of paragraph (h)(1). They state that 
Revision 1 of the service bulletin specifies that repaired areas are 
inspected only in accordance with Part 6 of the Work Instructions, and 
that there is no path that could lead back to Part 1. They also state 
that paragraph (h) of the NPRM is relevant to repair and post-repair 
inspections, and that Part 1 applies to neither.
    We partially agree. We agree with Boeing that Revision 1 of Boeing 
Alert Service Bulletin 747-53A2439 refers only to Part 6 for post-
repair inspections, and that paragraph (h) is relevant to repair and 
post-repair inspections. Part 6 describes procedures for inspecting 
areas that have been repaired in accordance with Figure 8, 9, 10, or 12 
of the service bulletin. However, we do not agree with them that the 
reference to Part 1 should be deleted. The procedures specified in Part 
1 are applicable to areas that have been repaired by hole over-sizing 
only (without reinforcement) in accordance with Part 3. We find that no 
change to the AD is necessary in this regard.

Request To Clarify Repetitive Inspection Interval

    Boeing also requests that we clarify the repetitive inspection 
intervals in paragraphs (g)(2)(i) through (g)(2)(iii) and 
(g)(2)(iii)(A) of the NPRM. Because paragraph (g)(2) of the NPRM 
specifies repetitive inspection requirements, they believe that 
specifying ``repeat'' in paragraphs (g)(2)(i) through (g)(2)(iii) is 
redundant. They also note that paragraphs (g)(2)(ii) and (g)(2)(iii) 
state, ``Repeat that inspection * * *.'' They point out that, at the 
time of any inspection if no crack is found, an operator has a choice 
of doing the inspection specified in paragraph (g) of the NPRM in 
accordance with Part 1 or 2 and thus the interval could change. 
Therefore, they suggest that the compliance time in paragraphs 
(g)(2)(i) through (g)(2)(iii) apply only to the ``next inspection.''
    We partially agree. We agree with Boeing that clarification is 
necessary. We have revised paragraph (g) to clarify that, during the 
repetitive inspections, any combination of the applicable inspection 
methods may be used, provided that the corresponding repetitive 
interval is used. We do not agree with the changes that they suggested 
to paragraph (g)(2)(iii)(A). We used that language to correspond with 
the requirements of paragraph (a)(2) of AD 2004-03-11, which has been 
revised and re-identified as paragraph (g)(2)(iii)(A) in this AD.

Request To Refer to Upper Chords Rather Than Airplanes

    In addition, Boeing requests that paragraph (h) of the NPRM refer 
to ``upper chords'' instead of ``airplanes.''

[[Page 18620]]

They believe that some operators will inspect or have inspected some 
upper chords in accordance with 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 will inspect or have inspected 
other chords in accordance with Part 2 of the Work Instructions due to 
more difficult access. They note that the service bulletin recommends 
the proposed inspection in accordance with Part 2 at some locations.
    We partially agree. We agree with Boeing's rationale for revising 
paragraph (h). However, we find that using the term ``areas'' rather 
than ``upper chord,'' as they suggested, in that paragraph will capture 
all areas that are being inspected in accordance with paragraph (g) of 
this AD. We have revised paragraph (h) accordingly.

Request Not To Delay Repetitive Inspections if Optional Repair/
Modification Is Done

    In addition, Boeing requests that we delete the second sentence in 
paragraph (h). As an alternative if that sentence is not deleted, they 
request that the requirement be clarified in the preamble under 
``Differences Between the Proposed AD and Service Bulletin.'' They 
state that Part 2 of the Work Instructions of Boeing Alert Service 
Bulletin 747-53A2439, dated July 5, 2001; and Revision 1, dated March 
10, 2005; provides no instructions path for operators to jump from Part 
2 to Part 3, because operators would not choose to do hole repairs if 
fasteners have not been removed and no cracks have been found.
    We do not agree. As explained in the preamble of the NPRM under 
``Change to Existing AD,'' this AD retains certain requirements of AD 
2004-03-11. The optional repair/modification specified in paragraph (h) 
of this AD corresponds to requirements in paragraph (b) of AD 2004-03-
11. As explained in the preamble under ``Request To Expand Provisions 
for Optional Repair/Modification'' of AD 2004-03-11, we added the 
second sentence of paragraph (h) of this AD (paragraph (b) of AD 2004-
03-11) based on a request from Boeing. We have determined that 
providing the optional repair/modification specified in paragraph (h) 
is beneficial to operators. The repair procedures in Part 3 of the Work 
Instructions include procedures for doing an open hole high frequency 
eddy current inspection of the affected fastener holes. Therefore, we 
have determined that doing the optional repair/modification provides an 
acceptable level of safety and thus warrants an extension of the 
threshold for the initiation of the repetitive inspections required by 
paragraph (g)(2). In addition, we do not agree that this optional 
action differs from the service bulletin. We find that no change to the 
final rule is necessary in this regard.

Request To Add New Inspections and Reduce Inspection Threshold

    Boeing also requests that, for floor beam chords at stations 440 
and 520, we revise paragraph (h)(1) of the NPRM to lower the inspection 
threshold and to add new inspection requirements for a certain post-
repair/modification. They state that analysis has shown that additional 
inspections and a reduced inspection threshold are needed of the holes 
in the flange adjacent to the trim-out.
    We acknowledge Boeing's concern, but do not agree with their 
request. Since the suggested changes would expand the scope of the 
actions in this AD, additional rulemaking (i.e., supplemental NPRM) 
would be necessary to reopen the comment period. We find that to delay 
issuance of the AD would be inappropriate in light of the identified 
unsafe condition, and that the required inspections must be conducted 
to ensure continued safety. We may consider additional rulemaking, 
however, once the new inspection method is developed, approved, and 
available. We find that no change is necessary to this AD in this 
regard.

Request To Allow Not Counting Flight Cycles When Cabin Differential Is 
at 2.0 Pounds Per Square Inch (psi) or Less

    Further, Boeing requests that we revise paragraph (i) of the NPRM 
to allow not counting flight cycles in which cabin differential 
pressure is at 2.0 psi or less, when determining the number of flight 
cycles for compliance times. They state that this change would be 
consistent with the previous requirements for these inspections and is 
a continuance of the allowance for the upper deck floor beams given in 
paragraph (c) of AD 2004-03-11.
    We do not agree. There have been several instances on other in-
service reports where analytical rationales, similar to that of the 
commenter, have indicated that pressurization cycles less than 2.0 psi 
should not be counted. However, when fleet records have been examined, 
the airplanes engaging in such operations are having the same or 
greater occurrences of crack findings compared to those on which all 
pressurized flights are counted. As a result, we carefully consider 
such matters based on all available factors, including individual 
operator's specific maintenance programs, technical rationale, and 
fleet experience. We have found that such provisions are applicable 
only to a small number of operators that may not pressurize their 
airplanes above 2.0 psi in all their flights. We have determined that 
the best way to handle such circumstances is for operators to request 
an alternative method of compliance (AMOC) in accordance with paragraph 
(l) of this AD, rather than increasing the complexity of the AD by 
addressing each operator's unique situation.

Request To Give Credit to Previously Approved AMOC

    Boeing also requests that we revise paragraph (k)(3) of the NPRM 
(re-identified as paragraph (l)(3) in this AD) to add provisions for 
previously approved AMOCs that require post-modification/repair 
inspections. They contend that previously approved AMOCs meet the 
intent of paragraph (h) of the NPRM. They state that this change will 
reduce the need for new AMOCs.
    We agree and have added a reference to paragraph (h) in paragraph 
(l)(3) of this AD.

Request To Refer to Supplemental Structural Inspection Document (SSID) 
AD

    Lastly, Boeing requests that additional language be added to the 
NPRM to address its impact on AD 2004-07-22, amendment 39-13566 (69 FR 
18250, April 7, 2004), which mandated the SSID program for Boeing Model 
747 airplanes. (One correction of that AD was published in the Federal 
Register on April 13, 2004 (69 FR 19618); another correction was 
published on May 3, 2004 (69 FR 24063).) They state that, if the AD is 
adopted as proposed, operators will be required to do the SSID 
inspections and the inspections specified in Boeing Alert Service 
Bulletin 747-53A2439, Revision 1, without an allowance of doing the 
inspections specified in the service bulletin as a substitute for the 
SSID inspections. They also state that the inspections in the service 
bulletin provide damage detection as good as or better than SSID items 
F-19C for stations 340 through 420 inclusive, and 500; and F-20A for 
stations 440 and 520. In addition, they prefer that operators do the 
inspections in accordance with the service bulletin, because of the 
level of detailed instructions.
    We do not agree. We acknowledge that doing the inspections 
specified in Boeing Alert Service Bulletin 747-

[[Page 18621]]

53A2439, Revision 1, may be acceptable for compliance with certain 
requirements of AD 2004-07-22; however, no request for an AMOC to that 
AD has been submitted to us for approval in this regard. In addition, 
it is more appropriate to address AMOCs under the provisions of the 
applicable AD rather than a related AD. Under the provisions of 
paragraph (g) of AD 2004-07-22, we may consider requests for approval 
of an AMOC if sufficient data are submitted to substantiate that such 
action would provide an acceptable level of safety. We find that no 
change to this AD is necessary in this regard.

Clarification of AMOC Paragraph

    We have revised this action to clarify the appropriate procedure 
for notifying the principal inspector before using any approved AMOC on 
any airplane to which the AMOC applies.

Conclusion

    We have carefully reviewed the available data, including the 
comments that have been received, and determined that air safety and 
the public interest require adopting the AD with the changes described 
previously. We have determined that these changes will neither increase 
the economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

    There are about 78 airplanes of the affected design in the 
worldwide fleet. This AD will affect about 21 airplanes of U.S. 
registry.
    The inspections that are required by AD 2004-03-11 and retained in 
this AD take about 29 work hours per airplane, at an average labor rate 
of $65 per work hour. Based on these figures, the estimated cost of the 
currently required inspections for U.S. airplanes is $39,585, or $1,885 
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 AD will not have federalism 
implications under Executive Order 13132. This AD will 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 this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866;
    (2) Is not a ``significant rule'' under 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 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, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
removing amendment 39-13455 (69 FR 5920, February 9, 2004) and by 
adding the following new airworthiness directive (AD):

2006-08-02 Boeing: Amendment 39-14556. Docket No. FAA-2005-22423; 
Directorate Identifier 2005-NM-068-AD.

Effective Date

    (a) This AD becomes effective May 17, 2006.

Affected ADs

    (b) This AD supersedes AD 2004-03-11.

Applicability

    (c) This AD applies to Boeing Model 747-200C and -200F series 
airplanes, certificated in any category, as identified in Boeing 
Alert Service Bulletin 747-53A2439, dated July 5, 2001.

Unsafe Condition

    (d) This AD results from new reports of cracks in the upper deck 
floor beams occurring at lower flight cycles. We are issuing this AD 
to find and fix cracking in certain upper deck floor beams, which 
could extend and sever floor beams at a floor panel attachment hole 
location and could result in rapid decompression and loss of 
controllability 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.

Restatement of Requirements of AD 2004-03-11, but With a New Reduced 
Threshold and Reduced Repetitive Intervals for Certain Floor Beams:

Initial Compliance Time at a New Reduced Threshold

    (f) 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.

Inspections at Reduced Intervals for Certain Floor Beams and Repair

    (g) 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

[[Page 18622]]

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.

Optional Repair/Modification

    (h) 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.

New Requirements of This AD

Determining the Number of Flight Cycles for Compliance Time

    (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.

New Revision of Service Bulletin

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

                      Table 1.--Service Information
------------------------------------------------------------------------
               Do--                         In accordance with--
------------------------------------------------------------------------
(1) The actions required by         Parts 1 and 2 of the Work
 paragraph (g) of this AD.           Instructions of Boeing Alert
                                     Service Bulletin 747-53A2439,
                                     Revision 1, dated March 10,2005; as
                                     applicable.
(2) The applicable inspection of    Parts 1 and 6 of the Work
 the repaired area required by       Instructions of Boeing Alert
 paragraph (g)(1) of this AD.        Service Bulletin 747-53A2439,
                                     Revision 1, dated March 10, 2005;
                                     as applicable; at the applicable
                                     time per Table 1 of Part 3 of the
                                     Work Instructions of the service
                                     bulletin.
(3) The actions required by         Parts 1, 3, and 6 of the Work
 paragraph (h)(1) of this AD.        Instructions of Boeing Alert
                                     Service Bulletin 747-53A2439,
                                     Revision 1, dated March 10, 2005;
                                     as applicable.
(4) The actions required by         Figure 5 and Part 1 of the Work
 paragraph (h)(2) of this AD.        Instructions of Boeing Alert
                                     Service Bulletin 747-53A2439,
                                     Revision 1, dated March 10, 2005;
                                     as applicable.
------------------------------------------------------------------------

No Reporting Requirement

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

Alternative Methods of Compliance (AMOCs)

    (l)(1) The Manager, Seattle Aircraft Certification Office 
(SACO), FAA, has the authority to approve AMOCs for this AD, if 
requested in accordance with the procedures found in 14 CFR 39.19.
    (2) 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 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, and the approval must specifically refer to this AD.
    (3) AMOCs approved previously according to AD 2004-03-11 are 
approved as AMOCs for the corresponding provisions of paragraphs (f) 
through (h) of this AD.
    (4) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.

Material Incorporated by Reference

    (m) You must use Boeing Alert Service Bulletin 747-53A2439, 
dated July 5, 2001; or Boeing Alert Service Bulletin 747-53A2439, 
Revision 1, dated March 10, 2005; as applicable; to perform the 
actions that are required by this AD, unless the AD specifies 
otherwise.
    (1) The Director of the Federal Register approved the 
incorporation by reference of Boeing Alert Service Bulletin 747-
53A2439, Revision 1, dated March 10, 2005, in accordance with 5 
U.S.C. 552(a) and 1 CFR part 51.
    (2) On March 15, 2004 (69 FR 5920, February 9, 2004), the 
Director of the Federal Register approved the incorporation by 
reference of Boeing Alert Service Bulletin 747-53A2439, dated July 
5, 2001.
    (3) Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for a copy of this service information. You 
may review copies at the Docket Management Facility, U.S. Department 
of Transportation, 400 Seventh Street, SW.,

[[Page 18623]]

Room PL-401, Nassif Building, Washington, DC; on the Internet at 
http://dms.dot.gov; or at the National Archives and Records 
Administration (NARA).
    For information on the availability of this material at the 
NARA, call (202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

    Issued in Renton, Washington, on March 31, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 06-3432 Filed 4-11-06; 8:45 am]
BILLING CODE 4910-13-P