[Federal Register Volume 66, Number 76 (Thursday, April 19, 2001)]
[Proposed Rules]
[Pages 20111-20114]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-9669]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-331-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 all Boeing Model 747 series 
airplanes, that currently requires repetitive inspections to detect 
cracking of the forward and aft inner chords and the splice fitting of 
the forward inner chord of the station 2598 bulkhead, and repair, if 
necessary. This proposal would add repetitive inspections of an 
expanded inspection area, which would end the inspections specified in 
the existing AD. This proposal also would limit the applicability of 
the existing AD. This proposal is prompted by reports indicating 
fatigue cracking was found on airplanes that had accumulated fewer 
total flight cycles than the threshold specified in the existing AD. 
The actions specified by the proposed AD are intended to detect and 
correct fatigue cracking of the forward and aft inner chords, the frame 
support, and the splice fitting of the forward inner chord of the upper 
corner of the station 2598 bulkhead, which could result in reduced 
structural capability of the bulkhead and the inability of the 
structure to carry horizontal stabilizer flight loads.

DATES: Comments must be received by June 4, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-331-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-331-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-331-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-331-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On April 19, 2000, the FAA issued AD 2000-08-21, amendment 39-11707 
(65 FR 25281, May 1, 2000), applicable to all Boeing Model 747 series 
airplanes, to require repetitive inspections to detect cracking of the 
forward and aft inner chords and the splice fitting of the forward 
inner chord of the station 2598 bulkhead, and repair, if necessary. 
That action was prompted by reports of fatigue cracking found in those 
areas. The requirements of that AD are intended to detect and correct 
such cracking, which could result in reduced structural capability of 
the bulkhead and the inability of the structure to carry horizontal 
stabilizer flight loads.

Actions Since Issuance of Previous Rule

    Since the issuance of AD 2000-08-21, the FAA has received reports 
indicating the detection of fatigue cracking on certain Boeing Model 
747 series airplanes. Investigation revealed that on an airplane having 
7,325 total flight cycles, a 2.8-inch-long crack was found on the inner 
chord of the station 2598 bulkhead; on another airplane having 5,845 
total flight cycles, a 2.1-inch-long crack was found in the same area. 
Cracks also have been found on the frame support of the station 2598 
bulkhead, which was not included in the inspection area specified in 
the existing AD.

Issuance of New Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-53A2427, Revision 2, dated October 5,

[[Page 20112]]

2000, which describes procedures for initial and repetitive surface 
high frequency eddy current (HFEC) inspections of the forward and aft 
inner chords, the frame support, and the splice fitting of the forward 
inner chord of the upper corner of the station 2598 bulkhead to detect 
cracking. The repetitive HFEC inspections of an expanded area eliminate 
the need for the inspections required by the existing AD. The 
compliance time for doing the new initial inspection is reduced from 
the compliance time for doing the initial inspection that is specified 
in Boeing Alert Service Bulletin 747-53A2427, Revision 1, dated October 
28, 1999 (recommended as the appropriate source of service information 
for accomplishment of the actions specified in the existing AD); and 
the new repetitive inspections specified in Revision 2 of the service 
bulletin are to be accomplished more frequently than the repetitive 
inspections specified in Revision 1 of the service bulletin.

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 2000-08-21 to continue to require 
repetitive inspections to detect cracking of the forward and aft inner 
chords and the splice fitting of the forward inner chord of the station 
2598 bulkhead, and repair, if necessary. This proposal would add 
repetitive surface HFEC inspections of the forward and aft inner 
chords, the frame support, and the splice fitting, to find cracks, and 
repair, if necessary. Doing the new HFEC inspections would end the 
inspections specified in the existing AD. The actions would be required 
to be accomplished in accordance with the service bulletin described 
previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

    Operators should note the following:
    The service bulletin specifies that the manufacturer may be 
contacted for disposition of certain repair conditions, but this 
proposed AD would require the repair of those conditions to be 
accomplished per a method approved by the FAA, or per data meeting the 
type certification basis of the airplane approved by a Boeing Company 
Designated Engineering Representative who has been authorized by the 
FAA to make such findings.
    The service bulletin specifies the effectivity as line numbers 1 
through 1241 inclusive, due to incorporation of a production change 
(cold working certain fastener holes of the station 2598 bulkhead) on 
airplanes manufactured after line number 1241. Since issuance of the 
service bulletin, the manufacturer has determined that the chords with 
the cold-worked fastener holes also are susceptible to fatigue 
cracking. Due to this determination, the applicability in this proposed 
AD includes line numbers 1 through 1307 inclusive.
    For airplanes having line numbers 1242 through 1307 inclusive, one 
option for the compliance time for doing the initial inspection would 
be before the accumulation of 16,000 total flight cycles. The service 
bulletin specifies before the accumulation of 6,000 total flight 
cycles.

Interim Action

    This is interim action. The manufacturer has advised that it 
currently is developing a modification that will positively address the 
unsafe condition addressed by this AD. Once this modification is 
developed, approved, and available, the FAA may consider further 
rulemaking.

Cost Impact

    There are approximately 1,115 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 258 airplanes of U.S. 
registry would be affected by this proposed AD.
    The HFEC inspection that currently is required by AD 2000-08-21 
takes approximately 2 work hours per airplane to accomplish, at an 
average labor rate of $60 per work hour. Based on these figures, the 
cost impact of this inspection is estimated to be $120 per airplane.
    The detailed visual inspection that currently is required by AD 
2000-08-21 takes approximately 2 work hours per airplane to accomplish, 
at an average labor rate of $60 per work hour. Based on these figures, 
the cost impact of this inspection is estimated to be $120 per 
airplane, per inspection cycle.
    The HFEC inspections that are proposed in this AD action would take 
approximately 2 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 proposed inspection is estimated to be $120 per airplane, 
per inspection cycle.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or proposed 
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 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 39-11707 (65 FR 
25281, May 1, 2000), and by adding a new airworthiness directive (AD), 
to read as follows:

Boeing:  Docket 2000-NM-331-AD. Supersedes AD 2000-08-21, Amendment 
39-11707.

    Applicability: Model 747 series airplanes, line numbers 1 
through 1307 inclusive, certificated in any category.

[[Page 20113]]


    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 (g)(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 cracking of the forward and aft inner 
chords, the frame support, and the splice fitting of the forward 
inner chord of the upper corner of the station 2598 bulkhead, which 
could result in reduced structural capability of the bulkhead and 
the inability of the structure to carry horizontal stabilizer flight 
loads, accomplish the following:

Restatement of Requirements of 
AD 2000-08-21

Initial Inspection

    (a) Prior to the accumulation of 13,000 total flight cycles, or 
within 1,000 flight cycles after June 5, 2000 (the effective date of 
AD 2000-08-21, amendment 39-11707), whichever occurs later: 
Accomplish the requirements specified in paragraphs (a)(1) and 
(a)(2) of this AD.
    (1) Perform a high frequency eddy current inspection (HFEC) to 
detect cracking of the forward and aft inner chords of the station 
2598 bulkhead, in accordance with Boeing Alert Service Bulletin 747-
53A2427, dated December 17, 1998; or in accordance with Figure 2, 
Steps 1 and 2, of Boeing Alert Service Bulletin 747-53A2427, 
Revision 1, dated October 28, 1999.
    (2) Perform an HFEC inspection to detect cracking of the splice 
fitting along the upper and lower attachment to the forward inner 
chord of the station 2598 bulkhead, as shown in Figure 2, Detail A, 
of Boeing Alert Service Bulletin 747-53A2427, dated December 17, 
1998; or in accordance with Figure 2, Step 3, of Boeing Alert 
Service Bulletin 747-53A2427, Revision 1, dated October 28, 1999.

    Note 2: Operators should note that, although the splice fitting 
is NOT highlighted in Figure 2, Detail A, of Boeing Alert Service 
Bulletin 747-53A2427, dated December 17, 1998, as it is in Figure 2 
of Boeing Alert Service Bulletin 747-53A2427, Revision 1, dated 
October 28, 1999, the inspection required by paragraph (a)(2) of 
this AD must still be accomplished.

Repetitive Inspections

    (b) Within 3,000 flight cycles after accomplishment of the 
inspections required by paragraph (a) of this AD: Accomplish the 
inspections specified in paragraphs (b)(1) and (b)(2) of this AD. 
Repeat the inspections thereafter at intervals not to exceed 3,000 
flight cycles.
    (1) Perform a detailed visual inspection to detect cracking of 
the forward and aft inner chords of the station 2598 bulkhead, in 
accordance with Boeing Alert Service Bulletin 747-53A2427, dated 
December 17, 1998; or in accordance with Figure 3, Steps 1 and 2, of 
Boeing Alert Service Bulletin 747-53A2427, Revision 1, dated October 
28, 1999.

    Note 3: 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.''

    (2) Perform a detailed visual inspection to detect cracking of 
the splice fitting along the upper and lower attachment to the 
forward inner chord of the station 2598 bulkhead, as shown in Figure 
3, Detail A, of Boeing Alert Service Bulletin 747-53A2427, dated 
December 17, 1998; or in accordance with Figure 3, Step 3, of Boeing 
Alert Service Bulletin 747-53A2427, Revision 1, dated October 28, 
1999.

    Note 4: Operators should note that, although the splice fitting 
is NOT highlighted in Figure 3, Detail A, of Boeing Alert Service 
Bulletin 747-53A2427, dated December 17, 1998, as it is in Figure 3 
of Boeing Alert Service Bulletin 747-53A2427, Revision 1, dated 
October 28, 1999, the inspections required by paragraph (b)(2) of 
this AD must still be accomplished.

Repair

    (c) If any cracking is detected during the inspections required 
by paragraph (a)(1) or (b)(1) of this AD, prior to further flight, 
repair in accordance with Boeing Alert Service Bulletin 747-53A2427, 
dated December 17, 1998, Revision 1, dated October 28, 1999, or 
Revision 2, dated October 5, 2000; except as provided by paragraph 
(d) of this AD.
    (d) If any cracking is detected during the inspections required 
by paragraph (a)(2) or (b)(2) of this AD, or the alert service 
bulletin specifies that the manufacturer may be contacted for 
disposition of certain repair conditions, prior to further flight, 
repair in accordance with a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO); 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 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

Repetitive Inspections

    (e) Do a surface HFEC inspection of the forward and aft inner 
chords, the frame support, and the splice fitting of the forward 
inner chord of the upper corner of the station 2598 bulkhead to find 
cracking, in accordance with Boeing Alert Service Bulletin 747-
53A2427, Revision 2, dated October 5, 2000; at the latest of the 
times specified in paragraphs (e)(1) and (e)(2) of this AD, as 
applicable. Repeat the inspection after that at intervals not to 
exceed 1,500 flight cycles. Doing these inspections ends the 
inspections required by paragraphs (a) and (b) of this AD.
    (1) For airplanes having line numbers 1 through 1241 inclusive:
    (i) Before the accumulation of 6,000 total flight cycles.
    (ii) Within 500 flight cycles after the effective date of this 
AD.
    (iii) If the inspections specified in paragraph (a) or (b) of 
this AD were done before the effective date of this AD: Within 1,500 
flight cycles after accomplishment of the last inspection required 
by paragraph (a) or (b) of this AD, as applicable.
    (2) For airplanes having line numbers 1242 through 1307 
inclusive:
    (i) Before the accumulation of 16,000 total flight cycles.
    (ii) Within 500 flight cycles after the effective date of this 
AD.
    (iii) If the inspections specified in paragraph (a) or (b) of 
this AD were done before the effective date of this AD: Within 1,500 
flight cycles after accomplishment of the last inspection required 
by paragraph (a) or (b) of this AD, as applicable.

Repair

    (f) If any cracking is found during the inspections required by 
paragraph (e) of this AD, before further flight, repair in 
accordance with Boeing Alert Service Bulletin 747-53A2427, Revision 
2, dated October 5, 2000; except where the alert service bulletin 
specifies that the manufacturer may be contacted for disposition of 
certain repair conditions, before 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

    (g)(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 per 
AD 2000-08-21, amendment 39-11707, are approved as alternative 
methods of compliance with paragraphs (c) and (d) of this AD.

    Note 5: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.


[[Page 20114]]



Special Flight Permits

    (h) 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.

    Issued in Renton, Washington, on April 11, 2001.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-9669 Filed 4-18-01; 8:45 am]
BILLING CODE 4910-13-P