AD 2001-14-18

[Federal Register Volume 66, Number 144 (Thursday, July 26, 2001)]
[Rules and Regulations]
[Pages 38892-38896]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 01-18015]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-276-AD; Amendment 39-12329; AD 2001-14-18]
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 series airplanes, that 
currently requires inspections to detect fatigue cracking of the 
vertical beam webs and chords of the nose wheel well (NWW) and of the 
inner chord and web of the fuselage frames at body station (BS) 300 and 
BS 320, and repair, if necessary. This amendment expands the 
applicability of the existing AD to include additional airplanes, and 
adds new requirements for repetitive inspections to detect fatigue 
cracking of the NWW vertical beam webs and frames from BS 260 to BS 
320, and follow-on actions, if necessary, which would end the currently 
required inspections for airplanes subject to them. This amendment also 
provides terminating action for the new repetitive inspections. The 
actions specified by this AD are intended to detect and correct fatigue 
cracking of the NWW vertical beam webs and frames, which could result 
in collapse of the NWW pressure bulkhead and subsequent rapid 
decompression of the airplane. This action is intended to address the 
identified unsafe condition.

DATES: Effective August 30, 2001.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of August 30, 2001.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane

[[Page 38893]]

Group, P.O. Box 3707, Seattle, 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 96-26-04, 
amendment 39-9867 (61 FR 69026, December 31, 1996), which is applicable 
to certain Boeing Model 747 series airplanes, was published in the 
Federal Register on March 14, 2001 (66 FR 14867). The action proposed 
to continue to require inspections to detect fatigue cracking of the 
vertical beam webs and chords of the nose wheel well and of the inner 
chord and web of the fuselage frames at body station (BS) 300 and BS 
320, and repair, if necessary. The action also proposed to expand the 
applicability of the existing AD to include additional airplanes, and 
add new requirements for repetitive inspections to detect fatigue 
cracking of the nose wheel well vertical beam webs and frames from BS 
260 to BS 320, and follow-on actions, if necessary, which would end 
currently required inspections for airplanes subject to them. The 
action also provides terminating action for the new repetitive 
inspections.

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 from a single commenter.

Reference Applicable Revision Level of Service Bulletin

    Table 3 of the proposed AD contains the compliance schedule for 
accomplishment of the inspections in paragraph (c) of the proposed AD 
for previously inspected airplanes subject to Procedure 3, 4, or 6 of 
Boeing Alert Service Bulletin 747-53A2293, Revision 8, dated July 13, 
2000. The commenter requests that the FAA revise the column in Table 3 
that contains the compliance time for the initial inspection of the 
proposed AD. The commenter asks that the column headings specifically 
identify Boeing Service Bulletin, Revision 7, dated March 13, 1997, as 
the correct source for the definitions of Options 1 and 2 as specified 
in those columns. The commenter believes that the FAA intended to 
reference Revision 7 of the service bulletin in this case because that 
is the revision being used by most operators.
    The FAA partially concurs with the commenter's request. We find 
that it's necessary to revise Table 3 in this final rule, but the 
commenter's suggested remedy does not fully address the issue because 
operators could possibly be using issues of the service bulletin other 
than Revision 7. Furthermore, we have determined that the definitions 
of Option 1 and Option 2 have varied between revisions of the service 
bulletin. Therefore, we find it necessary to cite the original issue 
and Revisions 1 through 7 of the service bulletin, as well as to remove 
the references to Options 1 and 2 entirely, and instead specify the 
method of inspections included in those options. Table 3 of this final 
rule has been revised accordingly.

Extend Compliance Time for Paragraph (f)

    The commenter requests that the FAA extend the compliance time in 
paragraph (f) of the proposed AD for airplanes on which cracking was 
repaired prior to the effective date of this AD according to paragraph 
(a)(2) of the proposed AD. The commenter states that, if these 
airplanes have not been inspected per paragraph (a) of the proposed AD 
within the last 100 flight cycles before the effective date of this AD, 
the airplanes must be inspected per paragraph (c) of the proposed AD 
within 100 flight cycles after the effective date of this AD. The 
commenter states that if these same airplanes had not been repaired per 
paragraph (a)(2) of the proposed AD, they would have been allowed to 
wait until 500 flight cycles after the effective date of this AD to do 
the inspections in paragraph (c). The commenter states that its 
experience in the subject area shows that repairs per paragraph (a)(2) 
of the proposed AD should be significantly larger and stronger than 
published repairs per the Boeing 747 Structural Repair Manual, which 
should eliminate the need for these airplanes to be inspected within 
100 flight cycles after the effective date of this AD.
    The FAA concurs with the intent of the commenter's request, though 
not with its rationale. We do not concur that an airplane not repaired 
per paragraph (a)(2) of this AD would have a compliance time of 500 
flight cycles after the effective date of this AD. An unrepaired 
airplane would be subject to a compliance time of 100 or 500 flight 
cycles SINCE LAST INSPECTION (not since the effective date of this AD), 
depending on the method used for the last inspection.
    As explained in the preamble of the proposed AD, we intend 
paragraph (f) to apply to airplanes that may not have been inspected 
following repairs. Certain airplanes could have been repaired as early 
as 1997, with no inspections having been accomplished since that time. 
The compliance time of 100 flight cycles after the effective date of 
this AD in paragraph (f) of this AD ensures that all of these airplanes 
will be inspected promptly.
    However, the FAA does concur that paragraph (f) of the proposed AD 
could require certain airplanes--i.e., those inspected by internal 
detailed visual inspection and high frequency eddy current (HFEC) 
inspection, which allows a 1,500-flight-cycle repeat interval--to be 
inspected unnecessarily within 100 flight cycles after the effective 
date of this AD. Therefore, the FAA has revised paragraph (f) of this 
final rule to provide an extended compliance time of 500 flight cycles 
after the effective date of this AD for airplanes on which an internal 
detailed visual and HFEC inspection has been done according to Boeing 
Service Bulletin 747-53-2293 within the last 1,500 flight cycles before 
the effective date of this AD.

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 562 Model 747 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 179 
airplanes of U.S. registry will be affected by this AD.
    For affected airplanes, the inspections that are currently required 
by AD 96-26-04 take approximately 24 work hours per airplane, at an 
average labor rate of $60 per work hour. Based on these figures, the 
FAA estimates the cost impact of the currently required actions to be 
$1,440 per affected airplane, per inspection cycle.

[[Page 38894]]

    The new inspections that are required in this AD will take 
approximately 4 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the FAA 
estimates the cost impact of these new actions on U.S. operators to be 
$42,960, or $240 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 39-9867 (61 FR 
69026, December 31, 1996), and by adding a new airworthiness directive 
(AD), amendment 39-12329, to read as follows:

2001-14-18  Boeing: Amendment 39-12329. Docket 2000-NM-276-AD. 
Supersedes AD 96-26-04, Amendment 39-9867.

    Applicability: Model 747 series airplanes, line numbers 1 
through 685 inclusive, certificated in any category; except as 
excluded in the table below:

                                Airplanes Excluded From Applicability of This AD
----------------------------------------------------------------------------------------------------------------
 Airplane group (as listed in Boeing    Area 4 modified per
 Alert Service Bulletin 747-53A2293,  Boeing Service Bulletin    Zone 1 modified per    Excepted  from this AD?
  Revision 8, dated July 13, 2000)       (BSB) 747-53-2293?       BSB 747-53-2272?
----------------------------------------------------------------------------------------------------------------
1-11................................  Yes....................  Yes...................  Yes.
1-11................................  No.....................  Yes...................  No.
1-11................................  Yes....................  No....................  No.
12-13...............................  Yes....................  N/A...................  Yes.
12-13...............................  No.....................  N/A...................  No.
----------------------------------------------------------------------------------------------------------------


    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 (i)(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 nose wheel well (NWW) 
vertical beams and frames, which could result in collapse of the NWW 
pressure bulkhead and subsequent rapid decompression of the 
airplane, accomplish the following:

Restatement of Requirements of AD 96-26-04

Repetitive Inspections of Frame Inner Chord and Web and Repair

    (a) For airplanes with line numbers 1 through 678 inclusive on 
which the Section 41 frame replacement in zone 1 specified in Boeing 
Service Bulletin 747-53-2272 has not been accomplished: Prior to the 
accumulation of 10,000 total flight cycles, or within 50 flight 
cycles after January 6, 1997 (the effective date of AD 96-26-04, 
amendment 39-9867), whichever occurs later, perform a detailed 
visual inspection to detect fatigue cracking of the inner chord and 
web of the left side and right side of body station (BS) 300 and BS 
320 fuselage frames from the NWW side panel outboard to stringer 39, 
in accordance with normal maintenance practices. Pay particular 
attention to the area where the NWW vertical beam inner chord 
interfaces with the fuselage frame.
    (1) If no cracking is detected, repeat the detailed visual 
inspection thereafter at intervals not to exceed 100 flight cycles, 
until paragraph (c) of this AD is done.
    (2) 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. 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.

One-Time Inspection of Vertical Beam Webs and Chords and Repair

    (b) For airplanes with line numbers 1 through 678 inclusive on 
which the Section 41 frame replacement in zone 1 specified in Boeing 
Service Bulletin 747-53-2272 has not been accomplished: Prior to the 
accumulation of 10,000 total flight cycles, or within 50 flight 
cycles after January 6, 1997, whichever occurs later, perform a one-
time detailed visual inspection to detect fatigue cracking of the 
left and right side vertical beam webs and chords of the NWW at BS 
300 and BS 320, in accordance with normal maintenance procedures.
    (1) If no cracking is detected, no further action is required by 
this paragraph.
    (2) If any cracking is detected, prior to further flight, repair 
in accordance with a method approved by the Manager, Seattle

[[Page 38895]]

ACO. 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.

New Requirements of this AD

    Note 2: 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.''

Repetitive Inspections

    (c) Do inspections to detect fatigue cracking of NWW vertical 
beam webs and frames, as applicable, from BS 260 to BS 320 (``Area 
4''), per the applicable procedure shown in Table 1 of this AD and 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
747-53A2293, Revision 8, dated July 13, 2000. For affected 
airplanes, inspection per this paragraph ends the repetitive 
inspections required by paragraph (a). Table 1 follows:

                                 Table 1.--Determining the Applicable Procedure
----------------------------------------------------------------------------------------------------------------
                                  Area 4 inspected
                                  per the original
                                      issue or       Area 4 modified    Zone 1 modified    Applicable procedure
         Airplane group             revisions 1      per BSB 747-53-    per BSB 747-53-   and figures in service
                                  through 7 of BSB        2293?              2272?               bulletin
                                    747-53-2293?
----------------------------------------------------------------------------------------------------------------
1-11...........................  No...............  No...............  No...............  Procedure 1; Figures 4
                                                                                           and 19, and Figure
                                                                                           10; as applicable.
1-11...........................  No...............  No...............  Yes..............  Procedure 2; Figures
                                                                                           11 and 12.
1-11...........................  Yes..............  No...............  No...............  Procedure 3; Figures 4
                                                                                           and 13, and Figures
                                                                                           10 and 14; as
                                                                                           applicable.
1-11...........................  Yes..............  No...............  Yes..............  Procedure 4; Figures
                                                                                           11 and 15.
1-11...........................  No...............  Yes..............  No...............  Procedure 5; Figures
                                                                                           10, 16, and 17; as
                                                                                           applicable.
1-11...........................  Yes..............  Yes..............  No...............  Procedure 6; Figure
                                                                                           18; and Figure 10, 14
                                                                                           or 17; as applicable.
12-13..........................  No...............  No...............  N/A..............  Procedure 2; Figures
                                                                                           11 and 12.
12-13..........................  Yes..............  No...............  N/A..............  Procedure 4; Figures
                                                                                           11 and 15.
----------------------------------------------------------------------------------------------------------------

Repetitive Inspections: Compliance Schedule

    (d) For all airplanes, do the inspection in paragraph (c) of 
this AD per the schedule in Table 2 or Table 3 of this AD, as 
applicable, except as provided by paragraph (f) of this AD. 
Thereafter, repeat the inspection at the interval specified in Table 
2 or Table 3 of this AD, as applicable, until paragraph (h) of this 
AD is done. Tables 2 and 3 follow:

                              Table 2.--Compliance Schedule--Procedures 1, 2, and 5
----------------------------------------------------------------------------------------------------------------
                                                              Repeat the inspection in the service bulletin as
                                                                                  follows:
                                       Do the initial      -----------------------------------------------------
   For airplanes  subject to       inspection before  the      If most recent
                                         latest of           inspection was per   If most recent  inspection was
                                                             option 1, repeat at   per option 2, repeat at least
                                                                 least every                   every
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Procedure 1....................  10,000 total flight        1,500 flight cycles.  100 flight cycles.
                                  cycles or 100 flight
                                  cycles after the last
                                  inspection per paragraph
                                  (a) of this AD.
Procedure 2....................  10,000 total flight        1,500 flight cycles.  500 flight cycles.
                                  cycles or 1,500 500
                                  flight cycles after the
                                  effective date of this
                                  AD.
Procedure 5....................  10,000 total flight        1,500 flight cycles.  100 flight cycles.
                                  cycles or 500 flight
                                  cycles since
                                  modification of Area 4
                                  in accordance with BSB
                                  747-53-2293 or 100
                                  flight cycles after the
                                  effective date of this
                                  AD.
----------------------------------------------------------------------------------------------------------------


                              Table 3.--Compliance Schedule--Procedures 3, 4, and 6
----------------------------------------------------------------------------------------------------------------
                                Do the initial inspection as follows, as   Repeat the inspection in the service
                                               applicable:                         bulletin as follows:
                               ---------------------------------------------------------------------------------
                                   If most recent
                                  inspection used
                                   both detailed        If most recent
                                  visual and high      inspection used
   For airplanes  subject to       frequency eddy     only the detailed     If most recent      If most recent
                                   current (HFEC)     visual method, per  inspection was per  inspection was per
                                  methods, per the    the original issue   Option 1, repeat    Option 2, repeat
                                 original issue or      or Revisions 1      at least every      at least every
                                Revisions 1 through    through 7 of BSB
                                  7 of BSB 747-53-   747-53-2293, do the
                                    2293, do the         inspection:
                                    inspection:
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Procedure 3...................  Within 500 flight    Within 100 flight    1,500 flight        100 flight cycles.
                                 cycles since last    cycles since last    cycles.
                                 inspection.          inspection.
Procedure 4...................  Within 500 flight    Within 100 flight    1,500 flight        500 flight cycles.
                                 cycles since last    cycles since last    cycles.
                                 inspection.          inspection.
Procedure 6...................  Within 500 flight    Within 100 flight    1,500 flight        100 flight cycles.
                                 cycles since last    cycles since last    cycles.
                                 inspection.          inspection.
----------------------------------------------------------------------------------------------------------------


[[Page 38896]]

Exceptions to Inspections Per Paragraphs (a) and (b)

    (e) For airplanes subject to paragraphs (a) and (b) of this AD: 
Airplanes inspected per paragraph (c) of this AD within the 
compliance time specified in paragraphs (a) and (b) of this AD are 
not required to be inspected per paragraphs (a) and (b) of this AD.
    (f) For airplanes in Groups 1 through 11 on which cracking was 
repaired prior to the effective date of this AD per paragraph (a)(2) 
of this AD: If an inspection per paragraph (a) has not been done 
within the last 100 flight cycles before the effective date of this 
AD, do the inspection in paragraph (c) of this AD at the compliance 
time specified in paragraph (f)(1) or (f)(2) of this AD, as 
applicable.
    (1) If internal detailed visual and HFEC inspections according 
to BSB 747-53-2293 have been done within the last 1,500 flight 
cycles before the effective date of this AD: Do the inspection 
within 500 flight cycles after the effective date of this AD.
    (2) For airplanes not identified in paragraph (f)(1) of this AD: 
Do the inspection within 100 flight cycles after the effective date 
of this AD.

Corrective Actions

    (g) If any cracking is found during any inspection required by 
paragraph (c) or (d) of this AD, prior to further flight, perform 
corrective actions, including secondary inspections to detect 
further cracking, in accordance with the applicable procedure in the 
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
53A2293, Revision 8, dated July 13, 2000.

Optional Terminating Action

    (h) Replacement of vertical beams and frames, as applicable, in 
accordance with the applicable procedure in the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-53A2293, Revision 
8, dated July 13, 2000, ends the requirements of this AD.

Alternative Methods of Compliance

    (i)(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 96-26-04, amendment 39-9867, are approved as 
alternative methods of compliance with paragraphs (a) and (b) of 
this AD.

    Note 3: 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

    (j) 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

    (k) Except as specified in paragraphs (a) and (b) of this AD, 
the actions shall be done in accordance with Boeing Alert Service 
Bulletin 747-53A2293, Revision 8, dated July 13, 2000. This 
incorporation by reference was approved by the Director of the 
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 
51. 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

    (l) This amendment becomes effective on August 30, 2001.

    Issued in Renton, Washington, on July 12, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-18015 Filed 7-25-01; 8:45 am]
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