[Federal Register Volume 75, Number 36 (Wednesday, February 24, 2010)]
[Proposed Rules]
[Pages 8279-8285]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-3542]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0981; Directorate Identifier 2008-NM-073-AD]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Model 747 Airplanes

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

ACTION: Supplemental notice of proposed rulemaking (NPRM); reopening of 
comment period.

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SUMMARY: The FAA is revising an earlier NPRM for an airworthiness 
directive (AD) that applies to certain Model 747 airplanes. The 
original NPRM would have superseded an existing AD that currently 
requires repetitive inspections of the body station (BS) 2598 bulkhead, 
and corrective actions if necessary. The existing AD also currently 
requires a terminating modification for the repetitive inspections and 
a post-modification inspection of the modified area. The original NPRM 
proposed to continue to require those actions using revised service 
information. For certain airplanes, the original NPRM proposed to 
require new repetitive inspections, an interim modification, and post-
interim modification inspections. For certain airplanes, the original 
NPRM also proposed to require replacing any previously repaired aft 
inner chord and reinstalling the terminating modification. The original 
NPRM resulted from reports of cracked aft inner chords on airplanes 
after certain requirements of the existing AD were done. This new 
action revises the original NPRM for airplanes that are converted to 
the Model 747-400 large cargo freighter (LCF) configuration by reducing 
the threshold and repeat intervals of certain post-modification 
inspections. This new action also revises the original NPRM for all 
airplanes by proposing that certain inspections of the upper aft outer 
chords and diagonal brace attachment fittings, flanges, and rods 
continue after the terminating modification. We are proposing this 
supplemental NPRM to prevent fatigue cracking of the BS 2598 bulkhead 
structure, which could result in inability of the structure to carry 
horizontal stabilizer flight loads, and loss of controllability of the 
airplane.

DATES: We must receive comments on this supplemental NPRM by March 22, 
2010.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    For service information identified in this proposed AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-
544-5000, extension 1; fax 206-766-5680; e-mail [email protected]; 
Internet https://www.myboeingfleet.com. You may review copies of the 
referenced service information at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information 
on the availability of this material at the FAA, call 425-227-1221 or 
425-227-1152.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (telephone 800-647-5527) is in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

FOR FURTHER INFORMATION CONTACT: Ivan Li, Aerospace Engineer, Airframe 
Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind 
Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6437; 
fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2008-0981; 
Directorate Identifier 2008-NM-073-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    We proposed to amend part 39 of the Federal Aviation Regulations 
(14 CFR part 39) with a notice of proposed rulemaking (NPRM) for an AD 
(the ``original NPRM'') to supersede AD 2006-05-06, amendment 39-14503 
(71 FR 12125, March 9, 2006). The original NPRM applied to certain 
Model 747 airplanes. The original NPRM was published in the Federal 
Register on September 23, 2008 (73 FR 54751). The original NPRM 
proposed to require repetitive inspections of the body station (BS) 
2598 bulkhead, and corrective actions if necessary; and a terminating 
modification for the repetitive inspections and a post-modification 
inspection of the modified area. The original NPRM proposed to require 
those actions using revised service information. For certain airplanes, 
the original NPRM proposed to require new repetitive inspections, an 
interim modification, and post-interim modification inspections. For 
certain airplanes, the original NPRM also proposed to require replacing 
any previously repaired aft inner chord and reinstalling the 
terminating modification.

Actions Since Original NPRM was Issued

    Since we issued the original NPRM, Boeing informed us that the 
compliance times of certain post-modification inspections need to be 
revised for Model 747-400 series airplanes that have been modified to 
operate in a freighter configuration. These airplanes are referred to 
as large cargo freighters, or LCF. Boeing states that higher operating

[[Page 8280]]

stresses for the subject structure on the Model 747-400 LCF airplanes 
mean that these airplanes need a lower inspection threshold and shorter 
repeat intervals than those specified in the original NPRM. We agree, 
and we have revised paragraphs (m), (q), and (r) of the original NPRM 
to reduce the threshold and repetitive intervals.
    In addition, Boeing informed us that for all airplanes certain 
inspections of the upper aft outer chords and diagonal brace attachment 
fittings, flanges, and rods need to be continued after the terminating 
modification is accomplished. Adding the reinforcing modification and 
replacing the aft inner chord as specified in the NPRM does not alter 
the upper aft outer chord and diagonal brace attachment fittings, 
flanges, and rods. Therefore, we have revised paragraph (q) of the 
original NPRM to specify that certain inspections must continue after 
the terminating modification.

Comments

    We have considered the following comments on the original NPRM.

Request To Revise Costs of Compliance

    Northwest Airlines requests that we revise the ``Costs of 
Compliance'' section of the original NPRM to include Boeing's current 
cost of the modification kit. Northwest Airlines states that the 
current cost is $52,218 rather than the $33,716 quoted in the original 
NPRM.
    We agree that the cost of the modification kit has changed. We have 
revised the ``Costs of Compliance'' section of this supplemental NPRM 
to include the new cost of the kit.

Request To Delay the AD Pending Revised Service Information

    All Nippon Airways and Japan Airlines request that we delay issuing 
the AD until Boeing revises Alert Service Bulletin 747-53A2427 to 
Revision 5 (we referred to Boeing Alert Service Bulletin 747-53A2427, 
Revision 4, dated March 6, 2008, in the original NPRM). All Nippon 
Airways explains that it has discussed several discrepancies in 
Revision 4 with Boeing, and that Boeing clarified those discrepancies 
in an information notice (IN). All Nippon Airways states that, since 
INs are not approved by the FAA, it will be a burden to operators to 
request alternative methods of compliance (AMOCs) once the proposed 
rule is mandated. As an alternative, All Nippon Airways proposes that 
we include the additional information from the IN in the final rule.
    In addition, Boeing has informed us that there is a discrepancy in 
the modification drawing specified in Boeing Alert Service Bulletin 
747-53A2427, Revision 4, dated March 6, 2008. The drawing does not 
include a step to ``zero-time'' certain existing fastener holes in the 
affected areas. The zero-timing is intended to remove any undetectable 
cracks in the affected fastener holes.
    We agree that we should refer to the most recent service 
information possible. We have reviewed Boeing Service Bulletin 747-
53A2427, Revision 5, dated October 1, 2009. The revised service 
information includes the information in the IN referred to by the 
commenter (the IN clarifies fastener codes and repair instructions) and 
does not require any additional work on airplanes on which the 
inspections, interim modification, and repair specified in earlier 
revisions of the service bulletin were done. Therefore, we have revised 
paragraphs (i), (j), (o), (s), (t), (u), and (v) of this supplemental 
NPRM to refer to Boeing Service Bulletin 747-53A2427, Revision 5, dated 
October 1, 2009. We have also added new paragraph (w) to the 
supplemental NPRM to give credit for doing certain actions in 
accordance with Boeing Alert Service Bulletin 747-53A2427, Revision 4, 
dated March 6, 2008.
    We have also reviewed Boeing Service Bulletin 747-53-2473, Revision 
1, dated February 20, 2007; and Boeing Alert Service Bulletin 747-
53A2473, Revision 2, dated August 28, 2009. We referred to Boeing 
Service Bulletin 747-53-2473, dated March 24, 2005, as the appropriate 
source of service information for accomplishing the required actions 
specified in paragraph (m) of the NPRM.
    Boeing Service Bulletin 747-53-2473, Revision 1, dated February 20, 
2007, retains and clarifies the same procedures as in Boeing Service 
Bulletin 747-53-2473, dated March 24, 2005, and adds procedures to 
replace repaired aft inner chords on certain airplanes on which the 
actions specified in Boeing Service Bulletin 747-53-2473, dated March 
24, 2005, were done.
    Boeing Alert Service Bulletin 747-53A2473, Revision 2, dated August 
28, 2009, adds procedures to inspect to determine if certain fasteners 
were installed, and to do related investigative and corrective actions 
if necessary, for airplanes on which the support frame modification 
specified in Boeing Service Bulletin 747-53-2473, dated March 24, 2005; 
or Revision 1, dated February 20, 2007; was done. The related 
investigative actions include an open-hole high frequency eddy current 
(HFEC) inspection of the fastener holes of a certain type of fastener 
for cracks, and a review of maintenance records to verify that an open-
hole HFEC inspection was performed at certain other fastener holes and 
the holes were zero-timed. For airplanes on which the holes were not 
zero-timed, the service bulletin specifies an HFEC inspection of the 
holes for cracks, and corrective actions if necessary. Boeing Alert 
Service Bulletin 747-53A2473, Revision 2, dated August 28, 2009, also 
adds procedures to do post-modification inspections.
    We have revised paragraph (m) of this supplemental NPRM to refer to 
Boeing Service Bulletin 747-53-2473, Revision 1, dated February 20, 
2007; and Boeing Alert Service Bulletin 747-53A2473, Revision 2, dated 
August 28, 2009. We have revised paragraph (q) of this supplemental 
NPRM to refer to Boeing Alert Service Bulletin 747-53A2473, Revision 2, 
dated August 28, 2009.
    We have also revised paragraphs (n) and (r) of this supplemental 
NPRM to refer to Boeing Alert Service Bulletin 747-53A2473, Revision 2, 
dated August 28, 2009, for the post-modification inspections.

Explanation of Change to Paragraph (r) of This Supplemental NPRM

    Boeing Alert Service Bulletin 747-53A2473, Revision 2, dated August 
28, 2009, also adds procedures for post-modification inspections. In 
paragraph (r) of the NPRM, we specified doing a post-modification 
inspection for cracking and repair of any crack, in accordance with a 
method approved by the FAA. Because Boeing Service Bulletin 747-
53A2473, Revision 2, dated August 28, 2009, specifies doing support 
frame post-modification inspections, we have revised paragraph (r) of 
this supplemental NPRM to refer to that service bulletin. The support 
frame post-modification inspections consist of the following 
inspections specified in Parts 1, 2, and 3 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-53A2473, Revision 2, 
dated August 28, 2009.
    The ``Part 1--Support Frame Inspections'' include the following 
inspections:
     A detailed inspection for cracking of the support frame 
and access cut-out forward and aft sides at station 2598.
     A surface HFEC inspection for cracking of the lower floor 
support chord at station 2598.
     A low frequency eddy current (LFEC) inspection for 
cracking of the support frame outer chord at station 2598.
     A surface and open-hole HFEC inspection for cracking of 
the support

[[Page 8281]]

frame outer chord and fitting at station 2598.
     An ultrasonic or surface HFEC inspection for cracking of 
the support frame outer chord at station 2598.
    The ``Part 2--Hinge Support Inspection'' is an open-hole HFEC 
inspection for cracking in the back-up fittings, frame support fitting 
and hinge fitting at station 2598.
    The ``Part 3--Support Frame Inspections'' include the following 
inspections:
     Detailed inspections for cracking of the frame web around 
the periphery of the aft inner chord and the entire modified support 
frame.
     Surface HFEC inspections for cracking in the upper forward 
inner chord, aft inner chord, upper splice fitting, lower forward inner 
chord, and frame support fitting, lower splice fitting, hinge frame 
support fitting.
     An LFEC or open-hole HFEC for cracking in the upper aft 
inner chord.
     Ultrasonic inspections for cracking in the upper and lower 
forward inner chord and frame support fitting.
     A surface HFEC inspection for cracking of the frame web.
     An LFEC for cracking in the aft outer chord.

If any cracking is found, the service bulletin specifies the corrective 
action as contacting Boeing for repair data and doing the repair.
    Boeing Alert Service Bulletin 747-53A2473, Revision 2, dated August 
28, 2009, specifies that the initial compliance times for doing support 
frame post-modification inspections ranges between within 1,500 flight 
cycles after doing the modification to within 20,000 flight cycles 
after doing the modification, depending on the inspection and airplane 
configuration. The service bulletin specifies that the repetitive 
interval for the support frame post-modification inspections ranges 
between 1,000 flight cycles and 6,000 flight cycles, depending on the 
inspection.

Explanation of New Compliance Time for Certain Airplanes in Paragraph 
(m) of This Supplemental NPRM

    For airplanes that are modified as specified in paragraph (m) of 
the supplemental NPRM and are converted to the Model 747-400 Large 
Cargo Freighter (LCF) configuration, the repetitive inspection 
specified in paragraph (k)(2) of this AD must be done thereafter at 
intervals not to exceed 1,800 flight cycles. We have revised paragraph 
(m) of this AD accordingly.

Clarification of Compliance Time

    We have revised paragraph (q)(2) of this supplemental NPRM to 
specify that the applicable related investigative and corrective 
actions must be done before further flight, as specified in Boeing 
Alert Service Bulletin 747-53A2473, Revision 2, dated August 28, 2009.

Explanation of Change Made to Paragraph (x)(3) of This Supplemental 
NPRM

    Boeing Commercial Airplanes has received an Organization 
Designation Authorization (ODA), which replaces their previous 
designation as a Delegation Option Authorization (DOA) holder. We have 
revised paragraph (x)(3) of this AD to delegate the authority to 
approve an alternative method of compliance for any repair required by 
this AD to the Boeing Commercial Airplanes ODA.

Explanation of Added/Removed Paragraphs in the Supplemental NPRM

    We have added a new paragraph (d) to this supplemental NPRM to 
provide the Air Transport Association (ATA) of America subject code for 
this proposed AD. This code is added to make this supplemental NPRM 
parallel with other new AD actions. We have re-identified subsequent 
paragraphs accordingly.
    Paragraph (n) of the original NPRM indicates that, after the 
effective date of the AD, Boeing Alert Service Bulletin 747-53A2427, 
Revision 4, dated March 6, 2008, must be used to accomplish the 
requirements of paragraphs (h) and (i) of the original NPRM (i.e., 
paragraphs (i) and (j) of this supplemental NPRM). We have removed 
paragraph (n) of the original NPRM, and have referred to Boeing Service 
Bulletin 747-53A2427, Revision 5, dated October 1, 2009, in paragraphs 
(i) and (j) of this supplemental NPRM.

Explanation of Additional Change to ``Costs of Compliance'' Paragraph

    We have revised the ``Costs of Compliance'' section to clarify 
which costs are retained from AD 2006-05-06 and which costs are new in 
this supplemental NPRM.

Explanation of Changes Made to the Manufacturer Name

    We have revised this supplemental NPRM to identify the legal name 
of the manufacturer as published in the most recent type certificate 
data sheet for the affected airplane models.

FAA's Determination and Proposed Requirements of the Supplemental NPRM

    We are proposing this supplemental NPRM because we evaluated all 
pertinent information and determined an unsafe condition exists and is 
likely to exist or develop on other products of the same type design. 
Certain changes described above expand the scope of the original NPRM. 
As a result, we have determined that it is necessary to reopen the 
comment period to provide additional opportunity for the public to 
comment on this supplemental NPRM.

Costs of Compliance

    There are about 998 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD. The average labor rate 
is $80 per work hour.

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                Number of
                                     Work                                         U.S.-
              Action                 hours     Parts       Cost per airplane    registered       Fleet cost
                                                                                airplanes
----------------------------------------------------------------------------------------------------------------
Surface HFEC inspections (required       2         None  $160, per inspection          162  $25,920, per
 by AD 2006[dash]05[dash]06) and                          cycle.                             inspection cycle.
 open-hole HFEC inspections (new
 proposed action).
Detailed inspections (required by        2         None  $160, per inspection          162  $25,920, per
 AD 2006[dash]05[dash]06).                                cycle.                             inspection cycle.
Terminating modification               126      $52,218  $62,298.............          162  $10,092,276.
 (partially required by AD
 2006[dash]05[dash]06; additional
 modification actions in this new
 proposed action).

[[Page 8282]]

 
Interim modification (new proposed       4        4,000  $4,320..............          162  $699,840.
 action).
Replacement of previously repaired       2         None  $160................          162  $25,920.
 aft inner chords (new proposed
 action).
Support Frame upper Corner               8         None  $640................          162  $103,680.
 Fastener Inspection (new proposed
 action).
Post-modification inspection (new        4         None  $320................          162  $51,840.
 proposed action).
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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 supplemental NPRM 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.

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 39--AIRWORTHINESS 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 39-14503 (71 FR 12125, March 9, 2006) and adding the 
following new airworthiness directive (AD):

The Boeing Company: Docket No. FAA-2008-0981; Directorate Identifier 
2008-NM-073-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by March 22, 
2010.

Affected ADs

    (b) This AD supersedes AD 2006-05-06, Amendment 39-14503.

Applicability

    (c) This AD applies to The Boeing Company Model 747-100, 747-
100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 
747-400D, 747-400F, 747SR, and 747SP series airplanes, certificated 
in any category, line numbers 1 though 1307 inclusive.

Subject

    (d) Air Transport Association (ATA) of America Code 53: 
Fuselage.

Unsafe Condition

    (e) This AD results from reports of cracked aft inner chords on 
airplanes after certain requirements of the existing AD were done. 
We are issuing this AD to prevent fatigue cracking of the body 
station (BS) 2598 bulkhead structure, which could result in 
inability of the structure to carry horizontal stabilizer flight 
loads, and loss of controllability 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.

Restatement of Requirements of AD 2006-05-06

Repetitive High Frequency Eddy Current (HFEC) Inspections of the 
Bulkhead Frame Supports

    (g) Before the accumulation of 10,000 total flight cycles, or 
within 1,000 flight cycles after August 16, 2001 (the effective date 
of AD 2001-14-07, amendment 39-12318, which was superseded by AD 
2006-05-06), whichever occurs later: Do an open-hole HFEC inspection 
to find cracking of the bulkhead frame support under the hinge 
support fittings of the horizontal stabilizer on the left and right 
sides at BS 2598, in accordance with Figure 2 of the Accomplishment 
Instructions of Boeing Service Bulletin 747-53A2449, Revision 1, 
dated May 24, 2001; or Revision 2, dated March 14, 2002. Repeat the 
inspection after that at intervals not to exceed 3,000 flight 
cycles. Inspections accomplished before August 16, 2001, per Boeing 
Alert Service Bulletin 747-53A2449, dated June 8, 2000, are 
considered acceptable for compliance with the applicable inspection 
specified in this paragraph.

Repair of Any Cracked Bulkhead Frame Support

    (h) If any cracking is found during any inspection required by 
paragraph (g) of this AD, before further flight, repair using a 
method approved in accordance with the procedures specified in 
paragraph (x) of this AD.

[[Page 8283]]

Repetitive Inspections of Inner Chords, Frame Support Fitting, and 
Splice Fitting

    (i) Do a surface HFEC inspection of the forward and aft inner 
chords, the frame support, and the splice fitting of the forward 
inner chord of the upper corners of the station 2598 bulkhead to 
find cracking, in accordance with the Accomplishment Instructions of 
Boeing Alert Service Bulletin 747-53A2427, Revision 2, dated October 
5, 2000; Revision 3, dated September 27, 2001; or Boeing Service 
Bulletin 747-53A2427, Revision 5, dated October 1, 2009; at the 
latest of the times specified in paragraphs (i)(1) and (i)(2) of 
this AD, as applicable. Repeat the inspection after that at 
intervals not to exceed 1,500 flight cycles. After the effective 
date of this AD, Boeing Service Bulletin 747-53A2427, Revision 5, 
dated October 1, 2009, must be used.
    (1) For airplanes having line numbers 1 through 1241 inclusive:
    (i) Before the accumulation of 6,000 total flight cycles.
    (ii) Within 500 flight cycles after August 28, 2001 (the 
effective date of AD 2001-15-03, amendment 39-12337, which was 
superseded by AD 2006-05-06).
    (iii) For airplanes inspected before August 28, 2001, in 
accordance with Boeing Alert Service Bulletin 747-53A2427, dated 
December 17, 1998 (including inspections of the splice fitting); or 
Revision 1, dated October 28, 1999: Within 1,500 flight cycles after 
accomplishment of the last inspection done in accordance with the 
original service bulletin or Revision 1, as applicable.
    (2) For airplanes having line numbers 1242 through 1307 
inclusive:
    (i) Before the accumulation of 16,000 total flight cycles.
    (ii) Within 500 flight cycles after August 28, 2001.
    (iii) For airplanes inspected before August 28, 2001, in 
accordance with Boeing Alert Service Bulletin 747-53A2427, dated 
December 17, 1998 (including inspections of the splice fitting), or 
Revision 1, dated October 28, 1999: Within 1,500 flight cycles after 
accomplishment of the last inspection done in accordance with Boeing 
Alert Service Bulletin 747-53A2427, dated December 17, 1998; or 
Revision 1, dated October 28, 1999, as applicable.

Repair of Any Cracked Inner Chord, Frame Support, or Splice Fitting

    (j) If any cracking is found during the inspections required by 
paragraph (i) of this AD, before further flight, repair in 
accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 747-53A2427, Revision 2, dated October 5, 2000; 
Revision 3, dated September 27, 2001; or Boeing Service Bulletin 
747-53A2427, Revision 5, dated October 1, 2009. After the effective 
date of this AD, Boeing Service Bulletin 747-53A2427, Revision 5, 
dated October 1, 2009, must be used. Where Boeing Alert Service 
Bulletin 747-53A2427, Revision 2, dated October 5, 2000; Revision 3, 
dated September 27, 2001; or Boeing Service Bulletin 747-53A2427, 
Revision 5, dated October 1, 2009; specifies that the manufacturer 
may be contacted for disposition of certain repair conditions, 
before further flight, repair using a method approved in accordance 
with the procedures specified in paragraph (x) of this AD.

Repetitive Detailed Inspections of BS 2598 Bulkhead

    (k) Before the accumulation of 10,000 total flight cycles, or 
within 1,000 flight cycles after October 27, 2003 (the effective 
date of AD 2003-19-08, amendment 39-13311, which was superseded by 
AD 2006-05-06), whichever is later: Do a detailed inspection of the 
BS 2598 bulkhead for discrepancies (cracking, elongated fastener 
holes) of the areas specified in paragraphs (k)(1) and (k)(2) of 
this AD, in accordance with the Accomplishment Instructions of 
Boeing Alert Service Bulletin 747-53A2467, dated July 26, 2001; or 
Revision 1, dated April 28, 2005. Repeat the inspections after that 
at intervals not to exceed 3,000 flight cycles, except as required 
by paragraph (m) of this AD. Doing the modification specified in 
paragraph (m) or (q) of this AD terminates the inspection of the 
area specified in paragraph (k)(1) of this AD.
    (1) The lower aft inner chords.
    (2) The upper aft outer chords, and the diagonal brace 
attachment fittings, flanges, and rods.

    Note 1: 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.''

Repair of Any Cracked BS 2598 Bulkhead

    (l) If any discrepancy is found during any inspection required 
by paragraph (k) of this AD: Before further flight, repair in 
accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 747-53A2467, dated July 26, 2001; or Revision 1, 
dated April 28, 2005. If the service bulletin specifies to contact 
Boeing for appropriate action: Before further flight, repair using a 
method approved in accordance with the procedures specified in 
paragraph (x) of this AD.

Terminating Modification With New Compliance Time for Certain 
Airplanes for the Inspection Specified in Paragraph (k)(2) of This 
AD

    (m) Except as provided by paragraph (q) of this AD: Before the 
accumulation of 20,000 total flight cycles, or within 48 months 
after April 13, 2006 (the effective date of AD 2006-05-06), 
whichever occurs later, modify the bulkhead by doing all applicable 
actions including surface and open-hole HFEC inspections for 
cracking of the upper forward inner chords, aft inner chords, upper 
splice fittings, and frame support fittings, as specified in the 
Accomplishment Instructions of Boeing Service Bulletin 747-53-2473, 
dated March 24, 2005; Revision 1, dated February 20, 2007; or Boeing 
Alert Service Bulletin 747-53A2473, Revision 2, dated August 28, 
2009. Repair any cracks before further flight, in accordance with 
Boeing Service Bulletin 747-53-2473, dated March 24, 2005; Revision 
1, dated February 20, 2007; or Boeing Alert Service Bulletin 747-
53A2473, Revision 2, dated August 28, 2009. Where Boeing Service 
Bulletin 747-53-2473, dated March 24, 2005; Revision 1, dated 
February 20, 2007; or Boeing Alert Service Bulletin 747-53A2473, 
Revision 2, dated August 28, 2009 specifies that the manufacturer 
may be contacted for disposition of certain repair conditions: 
Before further flight, repair the cracks using a method approved in 
accordance with the procedures specified in paragraph (x) of this 
AD. Accomplishment of the modification terminates the requirements 
of paragraphs (g), (i), and (k)(1) of this AD. After the effective 
date of this AD, Boeing Alert Service Bulletin 747-53A2473, Revision 
2, dated August 28, 2009 must be used for the actions specified in 
this paragraph. For airplanes that are converted to the Model 747-
400 Large Cargo Freighter (LCF) configuration, repeat the inspection 
specified in paragraph (k)(2) of this AD thereafter at intervals not 
to exceed 1,800 flight cycles.

Post-Modification Inspection and Repair

    (n) Except as provided by paragraphs (q) and (r) of this AD: 
Within 20,000 flight cycles after doing the modification required by 
paragraph (m) of this AD, inspect the BS 2598 bulkhead for cracks, 
and repair any cracks before further flight, in accordance with a 
method approved by the Manager, Seattle Aircraft Certification 
Office (ACO).

New Requirements of This AD

Terminating Repair for Repetitive Surface HFEC Inspections

    (o) As of the effective date of this AD, accomplishing the aft 
inner chord repair required by paragraph (j) of this AD in 
accordance with the applicable structural repair manual (SRM) 
specified in the Accomplishment Instructions of Boeing Service 
Bulletin 747-53A2427, Revision 5, dated October 1, 2009, ends the 
repetitive surface HFEC inspections required by paragraph (i) of 
this AD for that side of the bulkhead only.

Replacement of Previously Repaired Aft Inner Chord and 
Reinstallation of Terminating Modification

    (p) For airplanes on which the terminating modification required 
by paragraph (m) of this AD has been done in accordance with Boeing 
Service Bulletin 747-53-2473, dated March 24, 2005: Within 1,500 
flight cycles after doing the modification, or within 1,000 flight 
cycles after the effective date of this AD, whichever occurs later, 
do a one-time general visual inspection for repairs installed 
previously on the left and right side aft inner chords. For 
airplanes with previously installed repairs, before further flight, 
do rework (i.e., replace any previously repaired aft inner chord 
with a new aft inner chord and reinstall the terminating 
modification), using a method approved in accordance with the 
procedures specified in paragraph (x) of this AD.

[[Page 8284]]

Revised Terminating Modification

    (q) Doing the applicable modification required by paragraph 
(q)(1) or (q)(2) of this AD at the applicable time terminates the 
requirements of paragraph (m) of this AD and the repetitive 
inspections required by paragraphs (g), (i), and (k)(1) of this AD. 
For airplanes that are converted to the Model 747-400 LCF 
configuration, the inspection specified in paragraph (k)(2) of this 
AD must be repeated thereafter at intervals not to exceed 1,800 
flight cycles.
    (1) For airplanes on which the terminating modification required 
by paragraph (m) of this AD has not been done as of the effective 
date of this AD: Before the accumulation of 20,000 total flight 
cycles, or within 18 months after the effective date of this AD, 
whichever occurs later, modify the bulkhead, in accordance with the 
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
53A2473, Revision 2, dated August 28, 2009; except that where Boeing 
Alert Service Bulletin 747-53A2473, Revision 2, dated August 28, 
2009, specifies to contact Boeing for modification data, the 
modification data must be approved in accordance with the procedures 
specified in paragraph (x) of this AD and the modification must be 
done within the times specified in this paragraph.
    (2) For airplanes on which the terminating modification required 
by paragraph (m) of this AD has been done in accordance with Boeing 
Service Bulletin 747-53-2473, dated March 24, 2005; or Revision 1, 
dated February 20, 2007; as of the effective date of this AD: Within 
1,000 flight cycles after the effective date of this AD, or within 
1,500 flight cycles after doing the modification, whichever occurs 
later, do a general visual inspection of the applicable areas 
specified in paragraphs (q)(2)(i) and (q)(2)(ii) of this AD to 
determine if certain fasteners are installed, and, before further 
flight, do all applicable related investigative and corrective 
actions, in accordance with the Accomplishment Instructions of 
Boeing Alert Service Bulletin 747-53A2473, Revision 2, dated August 
28, 2009; except where Boeing Alert Service Bulletin 747-53A2473, 
Revision 2, dated August 28, 2009, specifies to contact Boeing for 
repair or rework data, the data must be approved in accordance with 
the procedures specified in paragraph (x) of this AD and the repair 
or rework must be done before further flight.
    (i) For airplanes modified in accordance with Boeing Service 
Bulletin 747-53-2473, dated March 24, 2005: Inspect the upper 
forward inner chord, frame support fitting, and splice fitting.
    (ii) For airplanes modified in accordance with Boeing Service 
Bulletin 747-53-2473, Revision 1, dated February 20, 2007: Inspect 
the frame web and upper shear deck aft side; and the upper forward 
inner chord, frame support fitting, and splice fitting.

Post-Modification Inspection and Repair

    (r) For airplanes on which the terminating modification has been 
done in accordance with paragraph (m) or (q) of this AD: Perform 
post-modification inspections of the BS 2598 bulkhead for cracking, 
in accordance with Parts 1, 2, and 3 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-53A2473, Revision 
2, dated August 28, 2009. Do the inspections at the applicable times 
specified in Tables 6 through 9 of paragraph 1.E., ``Compliance,'' 
of Boeing Service Bulletin 747-53A2473, Revision 2, dated August 28, 
2009; except where the service bulletin specifies a compliance time 
after the date of the service bulletin, this AD requires compliance 
within the specified compliance time after the effective date of 
this AD. If any cracking is found during any inspection required by 
this paragraph, before further flight, repair using a method 
approved in accordance with the procedures specified in paragraph 
(x) of this AD. Repeat the inspections thereafter at the applicable 
times specified in Tables 6 through 9 of paragraph 1.E., 
``Compliance,'' of Boeing Service Bulletin 747-53A2473, Revision 2, 
dated August 28, 2009. Accomplishing the applicable inspections 
required by this paragraph terminates the requirements of paragraph 
(n) of this AD.

Open-Hole HFEC Inspection(s) and Terminating Repair

    (s) For airplanes on which the terminating modification required 
by paragraph (m) or (q) of this AD has not been done: Do an initial 
open-hole HFEC inspection to detect cracks in the bulkhead splice 
fitting, frame support fitting, and forward and aft inner chords on 
the left and right sides of the BS 2598 bulkhead, in accordance with 
the Accomplishment Instructions of Boeing Service Bulletin 747-
53A2427, Revision 5, dated October 1, 2009. Do the initial 
inspection at the applicable time specified in Table 1 or 3 of 
paragraph 1.E., ``Compliance,'' of Boeing Service Bulletin 747-
53A2427, Revision 5, dated October 1, 2009; except where Boeing 
Service Bulletin 747-53A2427, Revision 5, dated October 1, 2009, 
specifies a compliance time after the date on the service bulletin, 
this AD requires compliance within the specified compliance time 
after the effective date of this AD.
    (1) If no crack is detected, repeat the open-hole HFEC 
inspection thereafter at intervals not to exceed 1,500 flight 
cycles.
    (2) If any crack is detected, before further flight, repair it 
in accordance with the Accomplishment Instructions of Boeing Service 
Bulletin 747-53A2427, Revision 5, dated October 1, 2009; except 
where Boeing Service Bulletin 747-53A2427, Revision 5, dated October 
1, 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 (x) of this 
AD. Accomplishing the aft inner chord repair in accordance with the 
applicable structural repair manual (SRM) specified in the 
Accomplishment Instructions of Boeing Service Bulletin 747-53A2427, 
Revision 5, dated October 1, 2009, ends the repetitive surface and 
open-hole HFEC inspections required by paragraphs (i) and (s)(1), 
respectively, of this AD for that side of the bulkhead only.

Interim Modification

    (t) For Group 1 airplanes, as identified in Boeing Service 
Bulletin 747-53A2427, Revision 5, dated October 1, 2009, on which 
the SRM repair required by paragraph (j) or (s)(2) of this AD has 
not been done; and on which the terminating modification required by 
paragraph (m) or (q) of this AD has not been done: Before the 
accumulation of 12,000 total flight cycles, or within 1,500 flight 
cycles after the effective date of this AD, whichever occurs later, 
install the interim modification for the aft inner chords, in 
accordance with the Accomplishment Instructions of Boeing Service 
Bulletin 747-53A2427, Revision 5, dated October 1, 2009. 
Accomplishing the interim modification ends the repetitive surface 
and open-hole HFEC inspections required by paragraphs (i) and 
(s)(1), respectively, of this AD.

Post-Interim Modification/Repair Repetitive Surface and Open-Hole 
HFEC Inspections

    (u) For airplanes on which the interim modification required by 
paragraph (t) of this AD has been done or the SRM repair required by 
paragraph (j) or (s)(2) of this AD has been done; and on which the 
terminating modification required by paragraph (m) or (q) of this AD 
has not been done: At the applicable times specified in Table 1, 2, 
or 3 of paragraph 1.E., ``Compliance,'' of Boeing Service Bulletin 
747-53A2427, Revision 5, dated October 1, 2009, do a surface HFEC 
inspection to detect cracks on the forward side (unmodified area) of 
the bulkhead, and open-hole and surface HFEC inspections to detect 
cracks in the modified or repaired area, in accordance with the 
Accomplishment Instructions of Boeing Service Bulletin 747-53A2427, 
Revision 5, dated October 1, 2009. Repeat the open-hole and surface 
HFEC inspections thereafter at intervals not to exceed 1,500 flight 
cycles, until the modification required by paragraph (q) of this AD 
is done, as applicable; except that for airplanes on which the 
repair of any cracked aft inner chord has been done on only one side 
of the bulkhead in accordance with the applicable SRM as required by 
paragraph (j) or (s)(2) of this AD, the repetitive surface and open-
hole HFEC inspections required by paragraphs (i) and (s)(1), 
respectively, of this AD must continue to be done for the other side 
of the bulkhead.

Repair of Any Cracked Inner Chord, Splice Fitting, or Frame Support 
Fitting

    (v) If any crack is detected during any surface or open-hole 
HFEC inspection required by paragraph (u) of this AD, before further 
flight, repair any cracked inner chord, splice fitting, or frame 
support fitting, in accordance with the Accomplishment Instructions 
of Boeing Service Bulletin 747-53A2427, Revision 5, dated October 1, 
2009; except where Boeing Service Bulletin 747-53A2427, Revision 5, 
dated October 1, 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 
(x) of this AD.

Actions Accomplished According to Previous Issue of Service 
Bulletin

    (w) Inspections, interim modification, and repairs accomplished 
before the effective date of this AD in accordance with Boeing Alert 
Service Bulletin 747-53A2427, Revision 4, dated March 6, 2008, are

[[Page 8285]]

considered acceptable for compliance with the corresponding action 
specified paragraphs (i), (j), (s), (t), (u), and (v) of this AD.

Alternative Methods of Compliance (AMOCs)

    (x)(1) The Manager, Seattle 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 ATTN: Ivan Li, Aerospace 
Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind 
Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-
6437; fax (425) 917-6590. Or, e-mail information to [email protected].
    (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 principal maintenance inspector (PMI) or 
principal avionics inspector (PAI), as appropriate, or lacking a 
principal inspector, your local Flight Standards District Office. 
The AMOC approval letter must specifically reference this AD.
    (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 Boeing 
Commercial Airplanes Organization Designation Authorization (ODA) 
that 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.
    (4) AMOCs approved previously in accordance with AD 2006-05-06 
are approved as AMOCs for the corresponding provisions of this AD.

    Issued in Renton, Washington, on February 11, 2010.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2010-3542 Filed 2-23-10; 8:45 am]
BILLING CODE 4910-13-P