AD 2001-11-06

[Federal Register Volume 66, Number 112 (Monday, June 11, 2001)]
[Rules and Regulations]
[Pages 31124-31129]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 01-14001]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-283-AD; Amendment 39-12248; AD 2001-11-06]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to certain Boeing Model 747-100 series airplanes, that 
currently requires repetitive inspections to detect cracking of the 
outer chord of the body station (BS) 1480 upper and lower bulkhead and 
longeron splice fitting; repair, if necessary; and modification of the 
skin splice plate, the outer chord splice fitting, and the stringer 
interface of the lower bulkhead, if necessary. This amendment revises 
the applicability of the existing AD to add additional airplanes, 
requires accomplishment of previously optional inspections and 
clarifies those inspections, extends certain compliance times, and 
requires additional work in certain areas. This amendment is prompted 
by reports that fatigue cracking has been found in the outer chord of 
the BS 1480 bulkhead at the overwing longeron splice on airplanes not 
subject to the existing AD. The actions specified by this AD are 
intended to detect and correct fatigue cracking of the skin, splice 
fittings, bulkhead web, and outer chord of the BS 1480 upper and lower 
bulkhead and longeron splice fitting, which could result in reduced 
structural integrity of the fuselage and the inability to carry limit 
load.

DATES: Effective July 16, 2001.
    The incorporation by reference of Boeing Alert Service Bulletin 
747-53A2390, Revision 1; including Appendices A, B, C, and D; dated 
July 6, 2000; as listed in the regulations, is approved by the Director 
of the Federal Register as of July 16, 2001.
    The incorporation by reference of Boeing Alert Service Bulletin 
747-53A2390, dated July 31, 1997, as listed in the regulations, was 
approved previously by the Director of the Federal Register as of 
October 7, 1998 (63 FR 50508, September 22, 1998).

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,

[[Page 31125]]

Washington 98124-2207. This information may be examined at the Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Rick Kawaguchi, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-1153; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 98-20-25, 
amendment 39-10791 (63 FR 50508, September 22, 1998), which is 
applicable to certain Boeing Model 747-100 series airplanes, was 
published in the Federal Register on November 9, 2000 (65 FR 67311). 
The action proposed to revise the applicability of the existing AD to 
add additional airplanes, require accomplishment of previously optional 
inspections and clarify those inspections, extend certain compliance 
times, and require additional work in certain areas.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Revise Statement of Unsafe Condition

    One commenter requests that the FAA revise the statement of unsafe 
condition in various places in the proposed AD. The statement appears 
as follows in the proposal: ``The actions specified in this proposed AD 
are intended to detect and correct fatigue cracking of the outer chord 
* * *.'' The commenter states that cracking has also been found in the 
skin, splice fittings, and bulkhead web, in addition to the outer 
chord. The FAA concurs with the commenter's request, and has changed 
this statement accordingly in various locations in this final rule.

Give Credit for Revision 1 of Service Bulletin

    One commenter requests that the FAA revise the proposed rule to 
refer to Boeing Alert Service Bulletin 747-53A2390, Revision 1; 
including Appendices A, B, C, and D; dated July 6, 2000; in addition to 
the original issue of the service bulletin; as an acceptable source of 
service information for paragraph (a)(2). As justification for its 
request, the commenter states that operators of Boeing Model 747-400 
series airplanes may not have the original issue of the service 
bulletin available. The commenter also asks the FAA to revise Note 2 of 
the proposed AD to refer to Revision 1.
    The FAA concurs with the intent of the commenter's request, but not 
with its justification because paragraph (a)(2) of this AD does not 
apply to Model 747-400 series airplanes. The FAA acknowledges, however, 
that Boeing Alert Service Bulletin 747-53A2390, Revision 1, has 
previously been approved as an alternative method of compliance for the 
actions in paragraphs (a)(1) and (a)(2) of this AD. To clarify this, 
the FAA has revised this final rule to add Note 2 after paragraph (a) 
of this AD, which states that Revision 1 has been approved as an 
alternative method of compliance for paragraphs (a)(1) and (a)(2) of 
this AD. (Subsequent notes have been renumbered accordingly.) Also, the 
FAA has revised Note 3 of this final rule (which was Note 2 of the 
proposed rule) to refer to Revision 1 as well as the original issue of 
the service bulletin.

Revise Various Paragraphs for Clarification

    One commenter requests that, for clarity, the FAA make the 
following changes to the proposed rule, for the following reasons:
    <bullet> Revise the phrase ``in accordance with the flight safety 
inspection program'' to ``in accordance with the after[-]modification 
inspection program'' in paragraphs (d)(2), (e)(2), and (g)(2), because 
the inspections following the Plan ``B'' modification should not be 
confused with the flight safety inspections for Plan ``A.''
    <bullet> Revise the reference to Figures 6 and 7 in paragraph 
(e)(1) of the proposed rule to refer to only Figure 6, because Figure 7 
includes a one-time inspection already required under paragraph (e).
    <bullet> Revise the reference to ``Figure 3 or Figure 8'' in 
paragraph (g)(1) to read ``Figures 3 and 8,'' because Figures 3 and 8 
are both necessary to accomplish inspections per Plan ``A.''
    <bullet> Revise the statement ``Except as provided by paragraph (b) 
of this AD'' in paragraph (i) of the proposed rule to read ``Except as 
provided by paragraph (a)(1)(i) or (b) of this AD.'' Paragraph 
(a)(1)(i) also provides for repairs in accordance with a method 
approved by the Manager, Seattle ACO; or in accordance with data 
meeting the type certification basis of the airplane approved by a 
Boeing Company DER.
    The FAA concurs with the commenter's requests, and has revised the 
appropriate paragraphs of this final rule accordingly.
    The same commenter requests that the FAA revise paragraph (d)(1), 
paragraph (e), paragraph (e)(2), paragraph (g)(1), and paragraph (i) to 
refer to the original issue of Boeing Alert Service Bulletin 747-
53A2390, dated July 31, 1997, in addition to Revision 1, as an 
acceptable source of service information for the actions in those 
paragraphs. The commenter states that operators that accomplished 
requirements in accordance with the original issue of the service 
bulletin should receive credit for these actions.
    The FAA concurs with the intent of the commenter's request, and has 
added a new note, Note 6, to this AD to state that accomplishment of 
the actions specified in paragraphs (d)(1), (e), (e)(2), (g)(1), and 
(i) of this AD, in accordance with the original issue of Boeing Alert 
Service Bulletin 747-53A2390, is acceptable for compliance with those 
paragraphs.

Revise Paragraph (i) To Require FAA-Approved Repairs

    One commenter requests that the FAA revise paragraph (i) to require 
that damage beyond the repair limits specified in the service bulletin 
be repaired according to a method approved by the FAA. The commenter 
states that operators must contact Boeing or the FAA to ensure that 
damage beyond the specified limits is repaired so that the repair meets 
the FAA type certificate, and to have the repaired structure evaluated 
for reduced inspection thresholds and repeat intervals. (Structure at 
fastener holes that are oversized beyond the limits in the service 
bulletin will have reduced fatigue life, and cracks in the area may 
grow rapidly.)
    The FAA partially concurs with the commenter's request. The FAA 
considers that, as proposed, paragraph (b) of this AD would already 
require that operators repair any damage outside the limits specified 
in the service bulletin in accordance with a method approved by the FAA 
or with data meeting the type certification basis of the airplane 
approved by a Boeing Company Designated Engineering Representative who 
has been authorized by the Manager, Seattle Aircraft Certification 
Office, to make such findings. However, the FAA finds that explicitly 
stating this requirement in paragraph (i) may clarify the requirements 
of that paragraph. Thus, the FAA has revised paragraph (i) in this 
final rule accordingly.

[[Page 31126]]

Add Grace Period for and Clarify Paragraph (f)(2)

    One commenter requests that the FAA revise the compliance time in 
paragraph (f)(2) of the proposed AD from ``Prior to the accumulation of 
20,000 total flight cycles, or at the time of the next scheduled 
inspection of the lower bulkhead in accordance with paragraph (a)(2) of 
this AD, whichever occurs later,'' to ``20,000 total flight cycles, 
within 1,000 flight cycles of the effective date of the AD, or within 
10,000 flight cycles of the previous inspections accomplished in 
accordance with paragraph (g)(1) of this AD, whichever occurs latest.'' 
The commenter states that the proposed compliance time could cause 
airplanes to be grounded if an airplane has more than 20,000 total 
flight cycles but has not previously been inspected per paragraph 
(a)(2).
    The FAA does not concur with the commenter's request. The 
compliance times in paragraph (f)(2) only apply if an inspection of the 
lower bulkhead has been done per paragraph (a)(2). If an airplane has 
not been inspected per paragraph (a)(2), then the compliance time in 
paragraph (f)(1), which includes a grace period of 1,000 flight cycles 
after the effective date of this AD, applies. No change is necessary in 
this regard.
    Also in reference to paragraph (f)(2), the commenter notes that 
paragraph (a)(2) tells operators how, but not when, to inspect the 
bulkhead splice and bulkhead stringer interfaces. The FAA infers that 
the commenter is requesting that the FAA clarify the reference to 
paragraph (a)(2) in paragraph (f)(2) of this AD, and the FAA concurs 
with this request. Paragraph (a)(2)(ii) states that repetitive 
inspections are to be accomplished according to the flight safety 
inspection program, as specified in Figures 1 and 3 of the service 
bulletin. Figure 3 specifies the 10,000-flight-cycle repetitive 
interval. Therefore, the FAA finds that paragraph (f)(2) of this AD 
should refer to paragraph (a)(2)(ii) of this AD, and has revised that 
paragraph accordingly.

Increase Threshold for Inspections of Splice Area and Stringer 
Interface

    One commenter requests that the FAA revise the proposed rule to 
increase the compliance threshold for the inspections of the splice 
area (from 16,000 total flight cycles) and the stringer interface (from 
20,000 total flight cycles). The commenter suggests a threshold of 
25,000 total flight cycles. The commenter bases its request on 
inspections of its airplanes, many of which had more than 25,000 total 
flight cycles at the time of inspection. Though cracks were found, all 
were small enough to be removed by oversizing holes or installing 
bushing repairs.
    The FAA does not concur with the commenter's request. Service 
information from the airplane manufacturer shows that large bulkhead 
repairs have been necessary on airplanes in Groups 1 through 3 with as 
few as 19,387 total flight cycles. Also, replacement of bulkhead cap 
fittings has been necessary on airplanes in Groups 4 through 18 with as 
few as 13,206 total flight cycles. These findings are consistent with 
the fact that the subject cracking is caused by fatigue, which can 
initiate cracks on airplanes at a wide range of flight cycles. In view 
of this information, the fact that the commenter found no large cracks 
on its airplanes, though the airplanes had more than 25,000 total 
flight cycles, does not justify an increase in the compliance 
threshold. The FAA finds that the proposed compliance times are 
necessary to ensure an adequate level of safety, and no change to the 
final rule is necessary in this regard.

Request To Delete References to Appendices

    One commenter requests that the FAA revise paragraphs (c), (d), 
(d)(1), and (d)(2) of the proposed rule, to delete the references to 
Appendices C and D of the service bulletin. The commenter states that 
these paragraphs apply to airplanes in Groups 1 through 3, but 
Appendices C and D of the service bulletin only apply to airplanes in 
Groups 4 through 22. The commenter also asks the FAA to revise 
paragraph (e) to delete the reference to Appendix B of the service 
bulletin, because paragraph (e) applies to airplanes in Groups 4 
through 22, but Appendix B of the service bulletin only applies to 
airplanes in Groups 1 through 3.
    The FAA does not concur with the commenter's request. The 
references to the appendices with which the commenter is concerned are 
included in those paragraphs as a citation of the full service bulletin 
reference (Boeing Alert Service Bulletin 747-53A2390, Revision 1; 
including Appendices A, B, C, and D; dated July 6, 2000). If a service 
bulletin includes one or more appendices which are numbered separately 
from the main body of the service bulletin, the Office of the Federal 
Register requires the FAA to specify all appendices as part of every 
full citation of the service bulletin. No change to the final rule is 
necessary in this regard.

Give Credit for Previous Accomplishment of Paragraph (e)

    One commenter requests that the FAA revise paragraph (e) of the 
proposed AD to give credit for inspections accomplished prior to the 
effective date of the AD. The commenter specifically requests that the 
FAA include a grace period of 6,000 flight cycles since the last 
inspection in accordance with paragraph (e)(1) of the AD. (The 
repetitive interval for the subject inspection is 6,000 flight cycles.)
    The FAA concurs with the commenter's intent, but notes that credit 
for previously accomplished AD actions is always given by means of the 
phrase included in every AD, ``Required as indicated, unless 
accomplished previously.'' No change to the final rule is necessary in 
this regard.

Clarify Paragraphs (d)(2), (e)(2), and (g)(2)

    One commenter requests that the FAA revise paragraphs (d)(2), 
(e)(2), and (g)(2) of the proposed rule to state, ``* * * this 
paragraph postpones the repetitive inspection requirements * * *'' 
rather than, ``* * * this paragraph terminates the repetitive 
inspection requirements.'' The commenter states that the actions in the 
service bulletin do not terminate inspections, but rather postpone 
inspections until 10,000, 16,000, or 20,000 flight cycles, as 
applicable, after modification.
    The FAA does not concur with the commenter's request. The sentences 
in the paragraphs to which the commenter refers specify termination of 
the repetitive inspection requirements under Plan ``A.'' The paragraphs 
to which the commenter refers clearly state that inspections must still 
be accomplished in accordance with the after-modification inspection 
program. No change to the final rule is necessary in this regard.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    There are approximately 1,128 Model 747 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 259 
airplanes of U.S. registry will be affected by this AD.

[[Page 31127]]

    AD 98-20-25 applies to airplanes listed in Groups 1 through 3 of 
the service bulletin. The detailed visual inspection that is currently 
offered as one alternative for compliance with AD 98-20-25 takes 
approximately 16 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the currently required actions on U.S. operators is estimated 
to be $960 per airplane, per inspection cycle.
    For airplanes listed in Groups 1 through 3 in the service bulletin 
(34 U.S.-registered airplanes), the new detailed visual, ultrasonic, 
and open hole high frequency eddy current (HFEC) inspections of the 
upper bulkhead area that are required by this AD will take 
approximately 32 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of these inspections on U.S. operators is estimated to be 
$65,280, or $1,920 per airplane, per inspection cycle.
    For airplanes listed in Groups 4 through 22 in the service bulletin 
(191 U.S.-registered airplanes), the new detailed visual, ultrasonic, 
and open hole HFEC inspections of the upper bulkhead area that are 
required by this AD will take approximately 22 work hours per airplane 
to accomplish, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact of these inspections on U.S. operators 
is estimated to be $252,120, or $1,320 per airplane, per inspection 
cycle.
    For all airplanes listed in the applicability of this AD (259 U.S.-
registered airplanes), the new detailed visual, ultrasonic, and open 
hole HFEC inspections of the lower bulkhead/stringer interface area 
that are required by this AD will take approximately 30 work hours per 
airplane to accomplish, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of these required inspections 
on U.S. operators is estimated to be $466,200, or $1,800 per airplane, 
per inspection cycle.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the requirements of this 
AD action, and that no operator would accomplish those actions in the 
future if this AD were not adopted. The cost impact figures discussed 
in AD rulemaking actions represent only the time necessary to perform 
the specific actions actually required by the AD. These figures 
typically do not include incidental costs, such as the time required to 
gain access and close up, planning time, or time necessitated by other 
administrative actions.

Regulatory Impact

    The regulations adopted herein 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. Therefore, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    For the reasons discussed above, I certify that this action (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. A final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (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. Section 39.13 is amended by removing amendment 39-10791 (63 FR 
50508, September 22, 1998), and by adding a new airworthiness directive 
(AD), amendment 39-12248, to read as follows:

2001-11-06  Boeing: Amendment 39-12248. Docket 98-NM-283-AD. 
Supersedes AD 98-20-25, Amendment 39-10791.

    Applicability: Model 747 series airplanes, line numbers (L/N) 1 
through 1254 inclusive, certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (j)(1) 
of this AD. The request should include an assessment of the effect 
of the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To detect and correct fatigue cracking of the skin, splice 
fittings, bulkhead web, and outer chord of the body station (BS) 
1480 bulkhead at the overwing longeron splice, which could result in 
reduced structural integrity of the fuselage and the inability to 
carry limit load, accomplish the following:

Restatement of Requirements of AD 98-20-25: Repetitive Inspections and 
Repair

    (a) For Model 747-100 series airplanes, L/N 1 through 87 
inclusive: Prior to the accumulation of 10,000 total flight cycles, 
or within 45 days after October 7, 1998 (the effective date of AD 
98-20-25, amendment 39-10791), whichever occurs later, accomplish 
either paragraph (a)(1) or (a)(2) of this AD.

    Note 2: Inspections per Boeing Alert Service Bulletin 747-
53A2390, Revision 1; including Appendices A, B, C, and D; dated July 
6, 2000; have been approved as an alternative method of compliance 
for the actions in paragraphs (a)(1) and (a)(2) of this AD.

    (1) Perform a detailed visual inspection to detect cracking of 
the longeron splice fitting at BS 1480, the forward side of the 
outer chord of the BS 1480 bulkhead at the longeron splice fitting 
attachment bolts, and the aft side of the outer chord of the BS 1480 
bulkhead within two inches above the outer chord splice fitting, on 
both the left and right sides of the airplane.

    Note 3: Figure 5 of Boeing Alert Service Bulletin 747-53A2390, 
dated July 31, 1997, and Revision 1, dated July 6, 2000, provides an 
exploded view of the structural components of the splice area for 
the purpose of parts identification. (However, paragraph (a)(1) of 
this AD does not require the inspection described in Figure 5.)


    Note 4: For the purposes of this AD, a detailed visual 
inspection is defined as: ``An intensive visual examination of a 
specific structural area, system, installation, or assembly to 
detect damage, failure, or irregularity. Available lighting is 
normally supplemented with a direct source of good lighting at 
intensity deemed appropriate by the inspector. Inspection aids such 
as mirror, magnifying lenses, etc., may be used. Surface cleaning 
and elaborate access procedures may be required.''

    (i) If any cracking is detected, prior to further flight, repair 
in accordance with a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA; or in accordance with data 
meeting the type certification basis of the airplane approved by a 
Boeing Company Designated Engineering Representative (DER) who has 
been authorized by the Manager, Seattle

[[Page 31128]]

ACO, to make such findings. For a repair method to be approved by 
the Manager, Seattle ACO, as required by this paragraph, the 
approval letter must specifically reference this AD.
    (ii) Repeat the detailed visual inspection thereafter at 
intervals not to exceed 250 flight cycles, until the initial 
inspection required by paragraph (a)(2) or (d) of this AD is 
accomplished.
    (2) Perform detailed visual, ultrasonic, and open hole high 
frequency eddy current (HFEC) inspections to detect cracking of the 
upper and lower bulkhead, bulkhead outer chord, web, skin, splice 
components, and lower bulkhead/stringer interface, in accordance 
with Figures 5 and 8 of Boeing Alert Service Bulletin 747-53A2390, 
dated July 31, 1997. Additionally, for airplanes on which the 
inspection in ``Plan B'' of the service bulletin is accomplished, 
modify the skin splice plate, the outer chord splice fitting, and 
the stringer interface of the lower bulkhead, in accordance with the 
Accomplishment Instructions of the service bulletin. Accomplishment 
of these actions constitutes terminating action for the repetitive 
inspection requirements of paragraph (a)(1) of this AD.
    (i) If any cracking is detected, prior to further flight, repair 
in accordance with the service bulletin, except as provided by 
paragraph (b) of this AD.
    (ii) Repeat the inspections thereafter in accordance with the 
flight safety inspection program specified in Figures 1 and 3 of the 
service bulletin.
    (b) Where the service bulletin specifies that the manufacturer 
may be contacted for disposition of certain repair conditions, 
repair in accordance with a method approved by the Manager, Seattle 
ACO; or in accordance with data meeting the type certification basis 
of the airplane approved by a Boeing Company DER 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 approval letter must specifically 
reference this AD.

New Requirements of This AD: Groups 1 Through 3: Splice Area Work 
(Compliance Times)

    Note 5: Airplanes inspected in accordance with paragraph (a)(2) 
of this AD are not required to be inspected in accordance with 
paragraphs (c) and (d) of this AD.


    Note 6: Accomplishment of the actions specified in paragraphs 
(d)(1), (e), (e)(2), (g)(1), and (i) of this AD; in accordance with 
the original issue of Boeing Alert Service Bulletin 747-53A2390, 
dated July 31, 1997; is acceptable for compliance with those 
paragraphs.

    (c) For airplanes listed in Groups 1 through 3 in Boeing Alert 
Service Bulletin 747-53A2390, Revision 1; including Appendices A, B, 
C, and D; dated July 6, 2000; on which the requirements of paragraph 
(a)(2) of this AD have NOT been accomplished prior to the effective 
date of this AD: Accomplish paragraph (d) of this AD at the 
applicable time specified in paragraph (c)(1), (c)(2), or (c)(3) of 
this AD.
    (1) For airplanes on which the inspection specified in Boeing 
Service Bulletin 747-53-2333 has not been accomplished: Inspect 
prior to the accumulation of 10,000 total flight cycles, or within 
1,000 flight cycles after the effective date of this AD, whichever 
occurs later.
    (2) For airplanes on which the inspection specified in Boeing 
Service Bulletin 747-53-2333 has been accomplished, but the full 
modification specified in that service bulletin has not been 
accomplished: Inspect at the later of the times specified in 
paragraphs (c)(2)(i) and (c)(2)(ii) of this AD.
    (i) Prior to the accumulation of 10,000 total flight cycles, or 
within 2,000 flight cycles after accomplishment of the last 
inspection in accordance with Boeing Service Bulletin 747-53-2333, 
whichever occurs first.
    (ii) Within 1,000 flight cycles after the effective date of this 
AD.
    (3) For airplanes on which the full modification specified in 
Boeing Service Bulletin 747-53-2333 has been accomplished: Inspect 
at the later of the times specified in paragraphs (c)(3)(i) and 
(c)(3)(ii) of this AD.
    (i) Prior to the accumulation of 16,000 total flight cycles, or 
within 6,000 flight cycles after accomplishment of the full 
modification in accordance with Boeing Service Bulletin 747-53-2333, 
whichever occurs first.
    (ii) Within 1,000 flight cycles after the effective date of this 
AD.

Groups 1 Through 3: Splice Area Work (Inspections)

    (d) For airplanes listed in Groups 1 through 3 in Boeing Alert 
Service Bulletin 747-53A2390, Revision 1; including Appendices A, B, 
C, and D; dated July 6, 2000; on which the requirements of paragraph 
(a)(2) of this AD have NOT been accomplished prior to the effective 
date of this AD: At the applicable time specified in paragraph (c) 
of this AD, accomplish paragraph (d)(1) or (d)(2) of this AD. 
Accomplishment of the requirements of this paragraph constitutes 
terminating action for the repetitive inspection requirements 
specified in paragraph (a)(1) of this AD, or, for the upper bulkhead 
splice area ONLY, for the inspection requirements specified in 
paragraph (a)(2) of this AD.
    (1) Plan ``A'': Perform detailed visual, ultrasonic, and HFEC 
inspections to detect cracking of the splice area, in accordance 
with Plan ``A'' and Figure 5, as defined in the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-53A2390, Revision 
1; including Appendices A, B, C, and D; dated July 6, 2000. Repeat 
the inspections thereafter in accordance with the flight safety 
inspection program as specified under Plan ``A'' and Figure 1 of the 
service bulletin.
    (2) Plan ``B'': Modify the skin splice plate and outer chord 
splice fitting in accordance with Plan ``B,'' as defined in the 
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
53A2390, Revision 1; including Appendices A, B, C, and D; dated July 
6, 2000. Perform HFEC inspections and modification, then accomplish 
repeat open hole HFEC inspections, in accordance with the after-
modification inspection program, as specified under Plan ``B'' and 
Figure 1 of the service bulletin. Accomplishment of the modification 
and inspections in accordance with this paragraph terminates the 
repetitive inspection requirements in paragraph (d)(1) of this AD.

Groups 4 Through 22: Splice Area Work (Compliance Time and Inspections)

    (e) For airplanes listed in Groups 4 through 22 in Boeing Alert 
Service Bulletin 747-53A2390, Revision 1; including Appendices A, B, 
C, and D; dated July 6, 2000: Prior to the accumulation of 16,000 
total flight cycles, or within 1,000 flight cycles after the 
effective date of this AD, whichever occurs later, perform detailed 
visual and ultrasonic inspections to detect cracking of the bulkhead 
forward flange in accordance with Figure 7 of the service bulletin, 
and accomplish the requirements of either paragraph (e)(1) or (e)(2) 
of this AD.
    (1) Plan ``A'': Perform open hole HFEC inspections to detect 
cracking of the splice area, in accordance with Plan ``A'' and 
Figure 6, as defined in the Accomplishment Instructions of the 
service bulletin. Repeat the inspections thereafter in accordance 
with the flight safety inspection program as specified under Plan 
``A'' and in Figure 2 of the service bulletin.
    (2) Plan ``B'': Perform open hole HFEC inspections and 
modification of the upper bulkhead, bulkhead outer chord, web, skin, 
and splice components; in accordance with Plan ``B,'' as defined in 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
747-53A2390, Revision 1; including Appendices A, B, C, and D; dated 
July 6, 2000. Thereafter, repeat the open hole HFEC inspections in 
accordance with the after-modification inspection program as 
specified under Plan ``B'' and Figure 2 of the service bulletin. 
Accomplishment of the modification and inspections in accordance 
with this paragraph terminates the repetitive inspection 
requirements specified in paragraph (e)(1) of this AD.

All Airplanes: Lower Bulkhead/Stringer Interface Work (Compliance 
Times)

    (f) For all airplanes (L/N 1 through 1254 inclusive): At the 
applicable time specified in paragraph (f)(1) or (f)(2) of this AD, 
accomplish paragraph (g) of this AD.
    (1) For airplanes on which an inspection of the lower bulkhead 
has NOT been accomplished prior to the effective date of this AD in 
accordance with paragraph (a)(2) of this AD: Inspect prior to the 
accumulation of 20,000 total flight cycles, or within 1,000 flight 
cycles after the effective date of this AD, whichever occurs later.
    (2) For airplanes on which an inspection of the lower bulkhead 
HAS been accomplished prior to the effective date of this AD in 
accordance with paragraph (a)(2) of this AD: Inspect prior to the 
accumulation of 20,000 total flight cycles, or at the time of the 
next scheduled inspection of the lower bulkhead in accordance with 
paragraph (a)(2)(ii) of this AD, whichever occurs later.

All Airplanes: Lower Bulkhead/Stringer Interface Work (Inspections)

    (g) For all airplanes (L/N 1 through 1254 inclusive): At the 
applicable time specified in paragraph (f) of this AD, accomplish 
paragraph (g)(1) or (g)(2) of this AD. For

[[Page 31129]]

airplanes having L/N 1 through 87 inclusive, accomplishment of the 
requirements of this paragraph constitutes terminating action for 
the inspection requirements specified in paragraph (a)(2) of this AD 
for the lower bulkhead/stringer interface area ONLY.
    (1) Plan ``A'': Perform detailed visual and either ultrasonic or 
open hole HFEC inspections, as applicable, to detect cracking of the 
lower bulkhead/stringer interface area, in accordance with Plan 
``A'' and Figure 8, as defined in the Accomplishment Instructions of 
Boeing Alert Service Bulletin 747-53A2390, Revision 1; including 
Appendices A, B, C, and D; dated July 6, 2000. Repeat the 
inspections thereafter in accordance with the flight safety program 
as specified under Plan ``A'' and Figures 3 and 8 of the service 
bulletin.
    (2) Plan ``B'': Except as provided by paragraph (h) of this AD, 
perform open hole HFEC inspections and modification of the lower 
bulkhead/stringer interface area, in accordance with Plan ``B'' and 
Figure 19, as defined in the Accomplishment Instructions of Boeing 
Alert Service Bulletin 747-53A2390, Revision 1; including Appendices 
A, B, C, and D; dated July 6, 2000. Thereafter, repeat the detailed 
visual and either ultrasonic or open hole HFEC inspections, as 
applicable, in accordance with the after-modification inspection 
program as specified under Plan ``B'' and Figures 3 and 8 of the 
service bulletin. Accomplishment of the modification and inspections 
in accordance with this paragraph terminates the repetitive 
inspection requirements specified in paragraph (g)(1) of this AD.

Airplanes Modified With Original Service Bulletin: Post-Modification 
Work

    (h) For any airplane (L/N 1 through 1254 inclusive) on which the 
modification specified in paragraph (g)(2) was accomplished prior to 
the effective date of this AD in accordance with the original issue 
of Boeing Alert Service Bulletin 747-53A2390, dated July 31, 1997: 
Prior to the accumulation of 20,000 total flight cycles, or within 
2,000 flight cycles after the effective date of this AD, whichever 
occurs later, accomplish post-modification work in accordance with 
Figure 26 of Boeing Alert Service Bulletin 747-53A2390, Revision 1; 
including Appendices A, B, C, and D; dated July 6, 2000.

Repair

    (i) Except as provided by paragraph (a)(1)(i) or (b) of this AD, 
if any cracking is detected during any inspection required by this 
AD, prior to further flight, repair in accordance with Boeing Alert 
Service Bulletin 747-53A2390, Revision 1; including Appendices A, B, 
C, and D; dated July 6, 2000. If any damage is found that is beyond 
the limits specified in the service bulletin, prior to further 
flight, repair in accordance with a method approved by the Manager, 
Seattle ACO; or in accordance with data meeting the type 
certification basis of the airplane approved by a Boeing Company DER 
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 approval letter must 
specifically reference this AD.

Alternative Methods of Compliance

    (j)(1) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Seattle ACO. Operators shall submit 
their requests through an appropriate FAA Principal Maintenance 
Inspector, who may add comments and then send it to the Manager, 
Seattle ACO.
    (2) Alternative methods of compliance, approved previously in 
accordance with AD 98-20-25, amendment 39-10791, are approved as 
alternative methods of compliance with paragraph (a) of this AD.

    Note 7: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (k) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.

Incorporation by Reference

    (l) Except as provided by paragraphs (a)(1), (a)(1)(i), 
(a)(1)(ii), (b), and (i) of this AD, the actions shall be done in 
accordance with Boeing Alert Service Bulletin 747-53A2390, dated 
July 31, 1997; or Boeing Alert Service Bulletin 747-53A2390, 
Revision 1; including Appendices A, B, C, and D; dated July 6, 2000; 
as applicable.
    (1) The incorporation by reference of Boeing Alert Service 
Bulletin 747-53A2390, Revision 1; including Appendices A, B, C, and 
D; dated July 6, 2000; is approved by the Director of the Federal 
Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) The incorporation by reference of Boeing Alert Service 
Bulletin 747-53A2390, dated July 31, 1997, was approved previously 
by the Director of the Federal Register as of October 7, 1998 (63 FR 
50508, September 22, 1998).
    (3) Copies may be obtained from Boeing Commercial Airplane 
Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be 
inspected at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Effective Date

    (m) This amendment becomes effective on July 16, 2001.

    Issued in Renton, Washington, on May 25, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-14001 Filed 6-8-01; 8:45 am]
BILLING CODE 4910-13-U