[Federal Register Volume 66, Number 210 (Tuesday, October 30, 2001)]
[Proposed Rules]
[Pages 54729-54731]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-27190]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-377-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 adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 747 series 
airplanes. This proposal would require repetitive inspections for 
cracking of the skin, bear strap, and sill chord of the lower lobe 
cargo door cutout, and repair, if necessary. This proposal also 
provides, for certain airplanes, an optional modification of the lower 
lobe cargo door cutout, which ends the pre-modification repetitive 
inspections, but would necessitate new post-modification repetitive 
inspections after a certain time. This action is necessary to find and 
fix cracking of the skin, bear strap, and sill chord of the lower lobe 
cargo door cutout, which could lead to reduced structural integrity of 
the lower lobe cargo door cutout, and result in rapid depressurization 
of the airplane. This action is intended to address the identified 
unsafe condition.

DATES: Comments must be received by December 14, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-377-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-377-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-377-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-377-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

[[Page 54730]]

Discussion

    The FAA has received reports indicating that cracking has been 
found in the upper corners of the lower lobe cargo door cutout on 
certain Boeing Model 747 series airplanes. Fatigue cracking of the 
skin, bear strap, and sill chord of the cargo door initiates at the 
fuselage skin fastener holes common to the hinge fairing strip. Such 
cracking, if not corrected, could lead to reduced structural integrity 
of the lower lobe cargo door cutout, and result in rapid 
depressurization of the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-53A2448, including Appendix A, dated September 28, 2000, which 
describes procedures for repetitive detailed visual and high frequency 
eddy current inspections for cracking of the skin, bear strap, and sill 
chord of the lower lobe cargo door cutout. If any cracking is found, 
the service bulletin specifies to contact the airplane manufacturer for 
repair instructions. For airplanes with no cracking and with adequate 
edge margins, the service bulletin also describes procedures for an 
optional modification of the lower lobe cargo door cutout. The optional 
modification involves removal of the hinge fairing and its fasteners, 
oversizing fastener holes, and replacing existing fasteners and the 
grounding strap with new fasteners and a new strap. Accomplishment of 
this optional modification eliminates the need to do the repetitive 
inspections described previously. However, Figure 5 of the service 
bulletin describes procedures for new post-modification repetitive 
detailed visual and high frequency eddy current inspections for 
cracking of the skin adjacent to the lower lobe cargo door cutout. If 
the optional modification is done, the post-modification inspections 
are eventually necessary. 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 require accomplishment of the actions specified in 
the service bulletin described previously, except as discussed below.

Differences Between Proposed AD and Service Bulletin

    Operators should note that, although the service bulletin specifies 
that the manufacturer may be contacted for disposition of repairs, this 
proposed AD would require all repairs 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 Manager, Seattle Aircraft 
Certification Office, to make such findings.
    Operators should note that the requirements of this proposed AD 
would apply only to airplanes with line numbers 1 through 1255 
inclusive, as listed in Group 1 in the service bulletin. Airplanes with 
line numbers 1256 through 1297 inclusive, which are identified as Group 
2 in the service bulletin, have cold-worked fastener holes near the 
edge of the skin panel at the upper corners of the door cutout. Thus, 
they are not as susceptible to the fatigue cracking addressed by this 
proposed AD. (Airplanes with line numbers 1298 and subsequent have a 
redesigned skin panel and increased edge margin at fastener locations. 
These airplanes are also not subject to the unsafe condition addressed 
by this proposed AD.)

Cost Impact

    There are approximately 1,129 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 275 airplanes of U.S. 
registry would be affected by this proposed AD, that it would take 
approximately 3 work hours per airplane to accomplish the proposed 
inspection, and that the average labor rate is $60 per work hour. Based 
on these figures, the cost impact of this proposed inspection on U.S. 
operators is estimated to be $49,500, or $180 per airplane, per 
inspection cycle.
    The cost impact figure discussed above is 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 adding the following new 
airworthiness directive:

Boeing: Docket 2000-NM-377-AD.
    Applicability: Model 747 series airplanes, line numbers 1 
through 1255 inclusive, certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (d) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or

[[Page 54731]]

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 find and fix cracking of the skin, bear strap, and sill chord 
of the lower lobe cargo door cutout, which could lead to reduced 
structural integrity of the lower lobe cargo door cutout, and result 
in rapid depressurization of the airplane, accomplish the following:

Repetitive Inspections

    (a) Perform detailed visual and high frequency eddy current 
inspections to find cracking of the skin, bear strap, and sill chord 
at the upper aft and forward corners of the lower lobe cargo door 
cutout, according to Boeing Alert Service Bulletin 747-53A2448, 
including Appendix A, dated September 28, 2000. Do the initial 
inspections at the time shown in paragraph (a)(1) or (a)(2) of this 
AD, as applicable, and repeat the inspections at least every 3,000 
flight cycles until paragraph (c) of this AD is accomplished.

    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.''

    (1) For airplanes with fewer than 13,000 total flight cycles as 
of the effective date of this AD: Do the inspection prior to the 
accumulation of 13,000 total flight cycles or within 1,000 flight 
cycles after the effective date of this AD, whichever is later.
    (2) For airplanes with 13,000 or more total flight cycles as of 
the effective date of this AD: Do the inspection within 1,000 flight 
cycles or 1 year after the effective date of this AD, whichever is 
first.

Repair

    (b) If any crack is found during any inspection required by 
paragraph (a) of this AD: Before further flight, repair 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 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 Manager's 
approval letter must specifically reference this AD.

Optional Modification

    Note 3: If edge margin distance is outside the limits specified 
in Figure 4 of Boeing Alert Service Bulletin 747-53A2448, including 
Appendix A, dated September 28, 2000, no modification is available.

    (c) If no crack is found during any inspection required by 
paragraph (a) of this AD, AND edge margin distance is within the 
limits specified in Figure 4 of Boeing Alert Service Bulletin 747-
53A2448, including Appendix A, dated September 28, 2000: Do 
paragraphs (c)(1) and (c)(2) of this AD.
    (1) Do the optional modification of the lower lobe cargo door 
cutout (including removing the hinge fairing and its fasteners, 
oversizing fastener holes, and replacing existing fasteners with new 
fasteners and the grounding strap with a new strap) described in the 
service bulletin. Such modification ends the repetitive inspections 
required by paragraph (a) of this AD.
    (2) Within 16,000 flight cycles after doing the modification in 
paragraph (c)(1) of this AD, perform detailed visual and high 
frequency eddy current inspections to find cracking of the skin at 
the upper aft and forward corners of the lower lobe cargo door 
cutout, according to Figure 5 of Boeing Alert Service Bulletin 747-
53A2448, including Appendix A, dated September 28, 2000. Repeat 
these inspections at least every 3,000 flight cycles.

Alternative Methods of Compliance

    (d) 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.

    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

    (e) 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 October 23, 2001.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-27190 Filed 10-29-01; 8:45 am]
BILLING CODE 4910-13-P