[Federal Register Volume 66, Number 50 (Wednesday, March 14, 2001)]
[Proposed Rules]
[Pages 14867-14871]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-6286]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-276-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Boeing Model 747 
series airplanes. That AD 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 action 
would expand the applicability of the existing AD to include additional 
airplanes, and add 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 
action also provides terminating action for the new repetitive 
inspections. The actions specified by the proposed 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.

DATES: Comments must be received by April 30, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-276-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2000-NM-276-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

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:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this action may be changed in 
light of the comments received.
    Submit comments using the following format:
     Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
     For each issue, state what specific change to the proposed 
AD is being requested.
     Include justification (e.g., reasons or data) for each 
request.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NM-276-AD.'' The postcard will be date stamped 
and returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 2000-NM-276-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On December 20, 1996, the FAA issued AD 96-26-04, amendment 39-9867 
(61 FR 69026, December 31, 1996), applicable to certain Boeing Model 
747 series airplanes, to require a one-time inspection to detect 
fatigue cracking of the vertical beam webs and chords of the nose wheel 
well (NWW) at body station (BS) 300 and BS 320, repetitive inspections 
to detect fatigue cracking of the inner chord and web of the fuselage 
frames at BS 300 and BS 320, and repair, if necessary. That action was 
prompted by a report indicating that the fuselage frames at BS 300 and 
BS 320 severed approximately 10 inches outboard of the NWW side panel 
and resulted in accelerated fatigue cracking

[[Page 14868]]

and subsequent failure of the adjacent NWW vertical beams. The 
requirements of that AD are intended to detect and correct such fatigue 
cracking, which could result in collapse of the NWW pressure bulkhead 
and subsequent rapid decompression of the airplane.

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, the FAA has received several reports 
of cracking in the NWW vertical beam webs and frames. On one airplane, 
a severed frame and vertical beam were found at BS 320 on the right-
hand side of the airplane. Additional cracking was found on the 
vertical beams at BS 300 and BS 320 on the left-hand side of the 
airplane. This airplane had accumulated 17,743 flight cycles.
    On another airplane, which had accumulated 17,329 flight cycles, 
cracks were found in the vertical beams at BS 300 and BS 320 on the 
left and right sides of the airplane, as well as in the top panel 
intercostal in the nose wheel well between BS 280 and BS 300.
    Based on these reports of cracking, the FAA has determined that the 
detailed visual inspections required by the existing AD are not 
adequate to detect fatigue cracking. Also, cracking may exist outside 
the areas required to be inspected per the existing AD. In addition, 
airplanes modified to have improved frames, per Boeing Service Bulletin 
747-53-2272, were excluded from the applicability of the existing AD. 
The FAA finds that, though these airplanes have improved frames, they 
still have the same vertical beams that are susceptible to fatigue 
cracking. For these reasons, the FAA finds that it is necessary to 
require additional inspections on airplanes affected by the existing AD 
and to expand the applicability of the existing AD to include airplanes 
with improved frames.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-53A2293, Revision 8, dated July 13, 2000. Among other things, this 
service bulletin describes new procedures for repetitive inspections to 
detect fatigue cracking of NWW vertical beam webs and frames from BS 
260 to BS 320 (defined in the service bulletin as ``Area 4''), and 
follow-on actions, if necessary. Inspection procedures include:
     Open-hole high frequency eddy current (HFEC) inspections 
to detect fatigue cracking of the BS 300 and BS 320 frame inner chords 
inboard of stringer 39,
     Surface HFEC inspections at all fastener locations common 
to the inner and outer chords of the NWW vertical beams, and
     Open-hole HFEC inspection of tool holes and insulation 
blanket standoff holes in the vertical beams.
    If any cracking is found, follow-on actions include secondary 
internal and external detailed visual inspections or an HFEC inspection 
of adjacent areas to detect any additional cracking, and repair or 
installation of a modification that involves replacing vertical beam 
webs and frames, as applicable, with new parts. This modification 
eliminates the need for the repetitive inspections described 
previously, and may also be done, but is not required, on airplanes 
with no cracking.
    Accomplishment of the actions specified in the service bulletin is 
intended to adequately address the identified unsafe condition.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would supersede AD 96-26-04 to continue to require, for 
currently affected airplanes, 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. The proposed AD would add new 
requirements for repetitive inspections to detect fatigue cracking of 
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 affected airplanes. The proposed AD also would provide 
an optional terminating action for the repetitive inspections. The 
actions would be required to be accomplished in accordance with the 
service bulletin described previously, except as discussed below in the 
section titled, ``Differences Between Service Bulletin and This 
Proposed AD.''
    Operators also should note that paragraph (f) of this proposed AD 
applies to airplanes in Groups 1 through 11 on which cracking was 
detected during the inspection required by paragraph (a) of the 
existing AD. Though the FAA intended that all airplanes subject to the 
existing AD must repeat the paragraph (a) inspection at regular 
intervals, the FAA has determined that airplanes on which cracking was 
repaired per paragraph (a)(2) may not have been repetitively inspected. 
Therefore, paragraph (f) of this proposed AD would require that 
affected airplanes not inspected per paragraph (a) within the last 100 
flight cycles be inspected per paragraph (c) of this AD within 100 
flight cycles after the effective date of this AD. The FAA has 
determined that such a compliance time is necessary to ensure continued 
safety of flight for these airplanes.

Interim Action

    This is considered to be interim action. The FAA is currently 
considering requiring the replacement of vertical beam webs and frames, 
as applicable, with new parts, which is provided in this AD as a 
required corrective action (for airplanes with cracking) or an optional 
terminating action (for airplanes without cracking). If the FAA decides 
to mandate such replacement, we will invite public comment at that 
time.

Differences Between Service Bulletin and This Proposed AD

    Procedure 1, as specified in the service bulletin, applies to 
(among other airplanes) certain airplanes in Groups 1 through 11 that 
are already subject to the inspections required by AD 96-26-04. For 
airplanes subject to Procedure 1, the service bulletin specifies a 
compliance time of the latest of 10,000 total flight cycles, 100 flight 
cycles after the last inspection per AD 96-26-04, or, for airplanes not 
yet inspected per AD 96-26-04, within 50 flight cycles after January 6, 
1997 (the effective date of AD 96-26-04). The FAA finds that this 
compliance time could be confusing for operators. Therefore, this 
proposed AD specifies a simpler compliance time of 10,000 total flight 
cycles or 100 flight cycles after the last inspection per paragraphs 
(a)(1) of this AD for the subject airplanes. Also, paragraph (e) of the 
proposed AD provides for airplanes subject to Procedure 1 that have not 
been inspected per the existing AD. That paragraph allows operators of 
affected airplanes to do paragraph (c) of this AD instead of paragraphs 
(a) and (b) of this AD, provided that the inspections are done at the 
compliance times provided in paragraphs (a) and (b).
    In addition, Procedure 2, as specified in the service bulletin, 
applies to airplanes in Groups 1 through 11 on which frame replacement 
per Boeing Service Bulletin 747-53-2272 has been done, as well as 
airplanes in Groups 12 and 13. For airplanes subject to Procedure 2, 
the service bulletin specifies a compliance time of 10,000 total flight 
cycles or 1,500 flight cycles after January 6, 1997 (the effective date

[[Page 14869]]

of the existing AD). The FAA finds that, because the airplanes subject 
to Procedure 2 were not included in the applicability of the existing 
AD, adopting the compliance time specified in the service bulletin 
could result in some airplanes being out of compliance with this 
proposed AD as of the effective date of this AD. The FAA finds that, 
while it is necessary for the affected airplanes to be inspected in a 
timely manner, it would be inappropriate to ground these airplanes 
until the required inspection can be done. Therefore, for airplanes 
subject to Procedure 2, this proposed AD includes a grace period of 100 
flight cycles after the effective date of this AD.

Cost Impact

    There are approximately 562 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 179 airplanes of U.S. registry 
would be affected by this proposed 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.
    The new inspections that are proposed in this AD action would 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 proposed requirements 
of this AD action, and that no operator would accomplish those actions 
in the future if this proposed 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 proposed herein 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. Therefore, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    For the reasons discussed above, I certify that this 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) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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), to read as follows:

Boeing: 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 Alert Service Bulletin 747-    Area 4 modified per      Zone 1 modified per BSB
 53A2293, Revision 8, dated July    Boeing Service Bulletin         747-53-2272?         Excepted from this AD?
            13, 2000)                  (BSB) 747-53-2293?
----------------------------------------------------------------------------------------------------------------
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

[[Page 14870]]

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 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:
                                                             ---------------------------------------------------
     For airplanes subject to      Do the initial inspection       If most recent            If most recent
                                      before the latest of       inspection was per        inspection was per
                                                                 Option 1, repeat at       Option 2, repeat at
                                                                     least every               least every
----------------------------------------------------------------------------------------------------------------
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 flight
                                    cycles after January 6,
                                    1997 or 100 flight
                                    cycles after the
                                    effective date of this
                                    AD.

[[Page 14871]]

 
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
                                                 applicable:                     service bulletin as follows:
                               ---------------------------------------------------------------------------------
                                                                               If most recent    If most recent
   For airplanes subject to         If most recent         If most recent      inspection was    inspection was
                                  inspection was per     inspection was per     per Option 1,     per Option 2,
                                   Option 1, do the       Option 2, do the     repeat at least   repeat at least
                                     inspection:            inspection:             every             every
----------------------------------------------------------------------------------------------------------------
Procedure 3...................  Within 500 flight      Within 100 flight      1,500 flight      100 flight
                                 cycles since last      cycles since last      cycles.           cycles.
                                 inspection.            inspection.
Procedure 4...................  Within 500 flight      Within 100 flight      1,500 flight      500 flight
                                 cycles since last      cycles since last      cycles.           cycles.
                                 inspection.            inspection.
Procedure 6...................  Within 500 flight      Within 100 flight      1,500 flight      100 flight
                                 cycles since last      cycles since last      cycles.           cycles.
                                 inspection.            inspection.
----------------------------------------------------------------------------------------------------------------

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 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 
Secs. 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.

    Issued in Renton, Washington, on March 7, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-6286 Filed 3-13-01; 8:45 am]
BILLING CODE 4910-13-P