[Federal Register Volume 66, Number 228 (Tuesday, November 27, 2001)]
[Proposed Rules]
[Pages 59180-59183]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-29426]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-355-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100, -200, -300, 
747SP, and 747SR 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-
100, -200, -300, 747SP, and 747SR series airplanes, that currently 
requires repetitive inspections to detect cracks in various areas of 
the fuselage internal structure, and repair, if necessary. This action 
would add new repetitive inspections for cracking of certain areas of 
the upper chord of the upper deck floor beams, and repair, if 
necessary. This proposal is prompted by the results of fatigue testing 
that revealed severed upper chords of the upper deck floor beams due to 
fatigue cracking. The actions specified by the proposed AD are intended 
to prevent loss of the structural integrity of the fuselage, which 
could result in rapid depressurization of the airplane.

DATES: Comments must be received by January 11, 2002.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-355-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 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-355-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

[[Page 59181]]

must submit a self-addressed, stamped postcard on which the following 
statement is made: ``Comments to Docket Number 2000-NM-355-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-355-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On April 22, 1993, the FAA issued AD 93-08-12, amendment 39-8559 
(58 FR 27927, May 12, 1993), applicable to certain Boeing Model 747 
series airplanes, to require repetitive inspections to detect cracks in 
various areas of the fuselage internal structure, and repair, if 
necessary. That action was prompted by results of fatigue tests that 
identified areas of the fuselage internal structure where fatigue 
cracks occurred. The requirements of that AD are intended to prevent 
loss of the structural integrity of the fuselage.

Actions Since Issuance of Previous Rule

    Since the issuance of AD 93-08-12, the FAA received a report that, 
during fatigue testing, severed upper chords were found on the upper 
deck floor beams on a Boeing Model 747 series airplane. The chords 
severed as a result of fatigue cracking. Additional reports were 
received that indicated the detailed internal visual inspections of the 
upper deck floor beams, mandated by AD 93-08-12 may not detect cracks 
before they become critical. Such conditions, if not corrected, could 
result in loss of the structural integrity of the fuselage, and rapid 
depressurization of the airplane.

Related AD

    On February 22, 2000, the FAA issued AD 2000-04-17, amendment 39-
11600 (65 FR 10695, February 29, 2000), applicable to certain Boeing 
Model 747-100, -200, and -300 series airplanes. That AD requires 
repetitive inspections to detect fatigue cracking in the chords and 
webs of certain upper deck floor beams, and repair of any cracking 
found. This proposed AD would require similar inspections of upper deck 
floor beams that were not addressed in that AD.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-53A2349, Revision 1, dated October 12, 2000, which describes 
procedures for detailed visual inspections for cracking in the 
following areas of the fuselage internal structure:
     Sections 41 and 42 upper deck floor beams
     Section 42 frames
     Section 46 frames
     Certain Section 41 bulkhead areas
    The service bulletin also describes procedures for repetitive 
detailed internal and external visual inspections of the main entry 
doors and door cutouts for cracking, and repetitive open hole high 
frequency eddy current inspections for cracking in the horizontal 
flanges of the upper chord of the Sections 41 and 42 upper deck floor 
beams. The new detailed visual inspection of Area 1 of Sections 41 and 
42 would eliminate the need for the existing inspection of those 
sections. If cracking is found, the service bulletin references the 747 
Structural Repair Manual (SRM) for repair instructions, or if the 
damage is beyond the limits specified in the service bulletin, the 
service bulletin specifies contacting Boeing for repair data.

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 93-08-12 to continue to require 
repetitive inspections to detect cracks in various areas of the 
fuselage internal structure, and repair, if necessary. The proposed AD 
would add new repetitive inspections for cracking of certain areas of 
the upper chord of the upper deck floor beams, and repair, if 
necessary. The actions would be required to be accomplished in 
accordance with the service bulletin described previously, except as 
discussed below.

Differences Between Proposed AD and Revision 1 of the Alert Service 
Bulletin

    This proposed AD differs from the service bulletin as follows:
     The service bulletin specifies that the manufacturer 
should 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 (DER) who has been authorized by 
the Manager, Seattle Aircraft Certification Office, to make such 
findings.
     The service bulletin specifies doing a high frequency eddy 
current inspection of the left and right sides of the upper deck floor 
beam at body station 380 between buttock lines 40 and 76, but this 
proposed AD would not require that inspection because it was mandated 
in AD 2000-04-17, amendment 39-11600 (65 FR 10695, February 29, 2000).
     The service bulletin specifies doing detailed visual and 
high frequency eddy current inspections of body station (BS) 380 
through BS 1000 inclusive, on each upper deck floor beam on Group 3 
airplanes. This proposed AD would extend the inspection area from BS 
380 through BS 1100 inclusive. The manufacturer has informed the FAA 
that the upper deck floor beams extend to BS 1100 for Group 3 
airplanes, and the service bulletin will be revised to reflect this 
change.
     The service bulletin also specifies that flight cycles 
with a cabin pressure differential of less than 2.0 pounds per square 
inch (psi) are not to be counted, but this proposed AD allows this 
stipulation only for Area 1 (Sections 41 and 42 upper deck floor beams) 
inspections. The FAA has determined that flight loads can significantly 
contribute to fatigue loads in other areas. Flights with less than 2.0 
psi cabin differential pressure can still have significant flight 
loads; therefore, the FAA cannot allow an adjustment to flight cycles 
for areas other than Area 1.
     Additionally, this proposed AD adds a grace period of 
3,000 flight cycles after doing the most recent inspection required by 
AD 93-08-12 for airplanes that have exceeded the compliance threshold 
specified in the service bulletin.

Explanation of Additional Changes to Requirements of Existing AD

    We have changed the requirements of the existing AD, as restated in 
this proposed AD, to remove all references to the use of ``FAA-approved 
procedures.'' This change is consistent with FAA policy in that regard. 
In place of this language, we have specified accomplishing repairs per 
a method approved by the FAA, or per data meeting the type 
certification basis of the airplane approved by a Boeing Company DER. 
We have determined that this change will not increase the economic 
burden on any operator, nor will it increase the scope of the proposed 
AD. A new paragraph (c) has been added to accommodate this change.

Interim Action

    This is considered to be interim action until similar action for 
Boeing Model 747-400 series airplanes and 747

[[Page 59182]]

freighter airplanes is identified, at which time the FAA may consider 
further rulemaking.

Cost Impact

    There are approximately 489 airplanes of the affected design in the 
worldwide fleet.
    The FAA estimates that 181 airplanes of U.S. registry are subject 
to the existing AD. The actions that are currently required by AD 93-
08-12 take approximately 1,746 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 is estimated to be 
$104,760 per airplane.
    We estimate that 155 airplanes of U.S. registry are subject to the 
new actions in this proposed AD. The new inspections that are proposed 
in this AD action would take approximately 255 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 requirements of this AD 
on U.S. operators is estimated to be $2,371,500, or $15,300 per 
airplane.
    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 39-8559 (58 FR 
27927, May 12, 1993), and by adding a new airworthiness directive (AD), 
to read as follows:

Boeing: Docket  2000-NM-355-AD. Supersedes AD 93-08-12, Amendment 
39-8559.
    Applicability: Model 747 series airplanes, as listed in Boeing 
Service Bulletin 747-53-2349, dated June 27, 1991, or Boeing Alert 
Service Bulletin 747-53A2349, Revision 1, dated October 12, 2000; 
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 (h)(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 prevent loss of the structural integrity of the fuselage, 
which could result in rapid depressurization of the airplane; do the 
following:

Restatement of Requirements of AD 93-08-12

Repetitive Inspections

    (a) Prior to the accumulation of 22,000 total flight cycles, or 
within 1,000 flight cycles after June 11, 1993 (the effective date 
of AD 93-08-12, amendment 39-8559), whichever occurs later, unless 
accomplished previously within the last 2,000 flight cycles; and 
thereafter at intervals not to exceed 3,000 flight cycles: Perform a 
detailed visual internal inspection to detect cracks in the areas of 
the fuselage internal structure specified in paragraphs (a)(1) 
through (a)(7) of this AD; in accordance with Boeing Service 
Bulletin 747-53-2349, dated June 27, 1991.
    (1) Sections 41 and 42 upper deck floor beams.
    (2) Section 42 upper lobe frames.
    (3) Section 46 lower lobe frames.
    (4) Section 42 lower lobe frames.
    (5) Main entry door cutouts.
    (6) Section 41 body station 260, 340, and 400 bulkheads.
    (7) Main entry doors.
    (b) Prior to the accumulation of 25,000 total flight cycles, or 
within 1,000 flight cycles after June 11, 1993, whichever occurs 
later, unless accomplished previously within the last 2,000 flight 
cycles; and thereafter at intervals not to exceed 3,000 flight 
cycles: Perform a detailed visual internal inspection to detect 
cracks in the Section 46 upper lobe frames, in accordance with 
Boeing Service Bulletin 747-53-2349, dated June 27, 1991.

Repair

    (c) Prior to further flight, repair any cracks detected during 
the inspections done per paragraph (a) or (b) of this AD, per a 
method approved by the Manager, Seattle Aircraft Certification 
Office (ACO), FAA; or per 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

    (d) Before the accumulation of 22,000 total flight cycles, or 
within 3,000 flight cycles after doing the most recent inspection 
required by paragraph (a) of this AD, whichever occurs later: Do a 
detailed visual inspection to find cracking in the areas specified 
in paragraph (d)(1) or (d)(2) of this AD, as applicable, per Figure 
2 of the Accomplishment Instructions of Boeing Alert Service 
Bulletin 747-53A2349, Revision 1, dated October 12, 2000. Repeat the 
inspection after that every 3,000 flight cycles. Doing this 
inspection terminates the inspections required by paragraph (a) of 
this AD in the area specified in paragraph (a)(1) of this AD only.
    (1) For Groups 1, 2, 4, and 5 airplanes: Do the inspections of 
Area 1 (sections 41 and 42 upper deck floor beams), including 
existing repairs and modifications.
    (2) For Group 3 airplanes: Do the inspections of Area 1 
(sections 41 and 42 upper deck floor beams from body stations 380 
through 1100 inclusive), including existing repairs and 
modifications.

    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as: ``An intensive visual examination of a 
specific

[[Page 59183]]

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.''

    (e) Before the accumulation of 28,000 total flight cycles, or 
within 3,000 flight cycles after doing the most recent inspection 
required by paragraph (a) of this AD, whichever occurs later: Do a 
high frequency eddy current (HFEC) inspection to find cracking of 
the open holes in the horizontal flanges of the upper chord of each 
upper deck floor beam in the areas specified in paragraph (e)(1) or 
(e)(2) of this AD, as applicable, per the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-53A2349, Revision 
1, dated October 12, 2000. Do the inspection per ``Inspection 
Alternatives,'' as specified in Sheet 7 of Figure 2 of the 
Accomplishment Instructions of the service bulletin. Repeat the 
applicable inspection according to the ``Repeat Inspection 
Intervals,'' specified in Sheet 7 of Figure 2 of the Accomplishment 
Instructions of the service bulletin.
    (1) For Group 1, 2, 4, and 5 airplanes: Do the inspections at 
the applicable locations (BS 380 through BS 780 inclusive for Groups 
1, 2, and 4, BS 380 through BS 860 inclusive for Group 5) as 
specified in Sheet 7 of Figure 2.
    (2) For Group 3 airplanes: Do the inspections as specified in 
Sheet 7 of Figure 2, at the upper deck floor beams from BS 380 
through BS 1100 inclusive.

    Note 3: HFEC inspections of the left and right sides of the 
upper deck floor beam at body station 380, between buttock lines 40 
and 76, done before the effective date of this AD per AD 2000-04-17, 
amendment 39-11600, are considered acceptable for compliance with 
the applicable inspections specified in paragraph (e) of this AD.

Adjustments to Compliance Time: Cabin Differential Pressure

    (f) For the purposes of calculating the compliance threshold and 
repetitive interval for the actions required by paragraphs (d) and 
(e) of this AD: For Area 1 only, the number of flight cycles in 
which cabin differential pressure is at 2.0 pounds per square inch 
(psi) or less need not be counted when determining the number of 
flight cycles that have occurred on the airplane, provided that 
flight cycles with momentary spikes in cabin differential pressure 
above 2.0 psi are included as full pressure cycles. For this 
provision to apply, all cabin pressure records must be maintained 
for each airplane: NO fleet-averaging of cabin pressure is allowed.

Repair

    (g) Before further flight, repair any cracking found during the 
inspections done per paragraphs (d) and (e) of this AD, according to 
Boeing Alert Service Bulletin 747-53A2349, Revision 1, dated October 
12, 2000. Where the service bulletin specifies to contact Boeing for 
repair instructions, repair per a method approved by the Manager, 
Seattle ACO; or per 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

    (h)(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 93-08-12, amendment 39-8559, are approved as 
alternative methods of compliance with this AD.

    Note 4: 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

    (i) 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 November 20, 2001.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-29426 Filed 11-26-01; 8:45 am]
BILLING CODE 4910-13-P