[Federal Register: June 21, 2002 (Volume 67, Number 120)]
[Proposed Rules]               
[Page 42207-42210]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr21jn02-14]                         

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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: Supplemental notice of proposed rulemaking; reopening of 
comment period.

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SUMMARY: This document revises an earlier proposed airworthiness 
directive (AD), applicable to certain Boeing Model 747 series 
airplanes, that would have required repetitive inspections for cracking 
of the skin, bear strap, and sill chord of the lower lobe cargo door 
cutout, and repair, if necessary. For certain airplanes, the proposed 
AD also would have provided an optional modification of the lower lobe 
cargo door cutout, which would have ended the pre-modification 
repetitive inspections, but would have necessitated new post-
modification repetitive inspections after a certain time. This new 
action, prompted by new crack findings, revises the proposed rule by 
expanding the optional modification of the lower lobe cargo door cutout 
and reducing the compliance threshold for the post-modification 
inspections. The proposed actions are 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 July 26, 2002.

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: 
9-anm-nprmcomment@faa.gov. 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: Technical Information: 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.
    Other Information: Judy Golder, Airworthiness Directive Technical 
Editor/Writer; telephone (425) 687-4241, fax (425) 227-1232. Questions 
or comments may also be sent via the Internet using the following 
address: judy.golder@faa.gov. Questions or comments sent via the 
Internet as attached electronic files must be formatted in Microsoft 
Word 97 for Windows or ASCII text.

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.

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to add an airworthiness directive (AD), applicable to 
certain Boeing Model 747 series airplanes, was published as a notice of 
proposed rulemaking (NPRM) in the Federal Register on October 30, 2001 
(66 FR 54729). That NPRM would have required repetitive inspections for 
cracking of the skin, bear strap, and sill chord of the lower lobe 
cargo door cutout, and repair, if necessary. For certain airplanes, 
that NPRM also would have provided an optional modification of the 
lower lobe cargo door cutout, which would have ended the pre-
modification repetitive inspections, but would have necessitated new 
post-modification repetitive inspections after a certain time. That 
NPRM was prompted by reports of cracking in the upper corners of the 
lower lobe cargo door cutout. Cracking of the skin, bear strap, and 
sill chord of the lower lobe cargo door cutout, if not found and fixed, 
could lead to reduced structural integrity of the lower lobe cargo door 
cutout, and result in rapid depressurization of the airplane.

Actions Since Issuance of Previous Proposal

    The actions proposed in the NPRM are specifically intended to 
address fatigue cracks of the skin, bear strap,

[[Page 42208]]

and sill chord of the cargo door cutout that initiate at the fuselage 
skin fastener holes common to the hinge fairing strip. Since the 
issuance of the NPRM, the FAA has received reports of cracks that 
initiated in the skin at additional fastener holes and from the edge of 
the cargo door cutout.
    Based on these new reports, we have determined that the 
modification of the lower lobe cargo door cutout and post-modification 
inspections per Boeing Alert Service Bulletin 747-53A2448, including 
Appendix A, dated September 28, 2000, which were provided in the NPRM 
as one option for compliance for certain airplanes, are no longer 
adequate.

Explanation of New Relevant Service Information

    Boeing has issued Alert Service Bulletin 747-53A2448, Revision 1, 
dated April 4, 2002. Revision 1 differs from the original issue of the 
service bulletin in the following ways:
     The modification has been expanded to include the 
replacement of several additional fasteners at the forward and aft 
corners of the aft cargo doors and a new surface high frequency eddy 
current inspection of the skin and bearstrap.
     The threshold for the initial post-modification inspection 
has been reduced from 16,000 to 10,000 flight cycles.
     A new alternative modification for airplanes without 
adequate edge margin has been added.
     References to certain chapters of the Structural Repair 
Manual (SRM) have been added as acceptable sources of service 
information for the accomplishment of certain repairs.
    Accomplishment of the actions specified in Revision 1 of the 
service bulletin is intended to adequately address the identified 
unsafe condition.

Comments

    Due consideration has been given to the comments received in 
response to the NPRM. Two commenters support the proposed rule. Certain 
comments have resulted in changes to the proposed AD.

Provide Service Information for Repairs and an Alternative Modification

    Two commenters request that the FAA refer to certain chapters of 
the SRM for instructions for accomplishing repairs. Paragraph (b) of 
the NPRM specifies that repairs are to be accomplished per a method 
approved by the FAA or per data approved by an authorized Boeing 
Company Designated Engineering Representative (DER). The commenters 
state that the proposed AD relates to an area that is the subject of 
existing SRM repairs. The commenters assert that such repairs should 
terminate the inspections that would be required by paragraph (a) of 
the proposed AD.
    Further, the same commenters also ask us to refer to certain 
chapters of the SRM for a modification of airplanes without adequate 
edge margins. Note 3 of the NPRM states that no modification is 
available for airplanes without adequate edge margin distance. One of 
the commenters notes that it is likely that there will be a significant 
number of airplanes with short edge margins.
    The FAA concurs. We have revised this supplemental NPRM to refer to 
Revision 1 of the service bulletin, discussed previously, which refers 
to certain chapters of the SRM for instructions to repair certain 
cracks. We find that the repairs in the SRM are sufficient for certain 
types of cracks and have revised paragraph (b) of this supplemental 
NPRM accordingly. Operators will note that, where the service bulletin 
specifies to contact Boeing for repair data, this proposed AD would 
require repairs to be accomplished per a method approved by the FAA or 
per data approved by an authorized Boeing Company DER.
    Revision 1 of the service bulletin also includes a new optional 
modification for airplanes without adequate edge margins. Therefore, we 
have not included Note 3 of the NPRM in this supplemental NPRM and have 
reordered subsequent notes accordingly, and we have revised paragraph 
(c) of this supplemental NPRM to acknowledge this optional 
modification.

Clarify Language in Discussion Section of NPRM

    One commenter requests that the FAA revise the ``Discussion'' 
section of the NPRM to indicate that ``fatigue cracking of the skin, 
bear strap, and sill chord of the cargo door CUTOUT initiates at the 
fuselage skin fastener holes common to the hinge fairing strip.'' The 
commenter indicates that this change is needed to clarify that the area 
of concern is not the cargo door but the fuselage structure at the 
corner of the cargo door cutout.
    We acknowledge that the word ``cutout'' was inadvertently omitted 
in the ``Discussion'' section of the NPRM, but note that it was 
included elsewhere in the NPRM where we referred to the subject area. 
Since the ``Discussion'' section of the NPRM is not restated in this 
supplemental NPRM, no change is possible in this regard.

Explanation of New Proposed Requirements

    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 inspections and corrective 
actions, if necessary, per Boeing Alert Service Bulletin 747-53A2448, 
Revision 1, except as discussed below under ``Differences Between 
Supplemental NPRM and Service Bulletin.'' The proposed AD would also 
provide for accomplishment of an optional modification and post-
modification inspections per Revision 1 of the service bulletin.

Differences Between Supplemental NPRM and Service Bulletin

    The proposed requirements specified in this supplemental NPRM 
differ from Revision 1 of the service bulletin in the following ways:
     The service bulletin specifies that the manufacturer may 
be contacted for disposition of certain repairs. However, the proposed 
AD would require such 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 DER who has been authorized by 
the FAA to make such findings.
     The requirements of the 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 the 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.)

Conclusion

    Since this change expands the scope of the originally proposed 
rule, the FAA has determined that it is necessary to reopen the comment 
period to provide additional opportunity for public comment.

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

[[Page 42209]]

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 (e) 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 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 and high frequency eddy current (HFEC) 
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, per Boeing Alert Service Bulletin 747-53A2448, Revision 1, 
dated April 4, 2002. 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 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.''


    Note 3: Inspections accomplished prior to the effective date of 
this AD according to Boeing Alert Service Bulletin 747-53A2448, 
including Appendix A, dated September 28, 2000, are considered 
acceptable for compliance with paragraph (a) of this AD.

    (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 the next flight, repair per Boeing 
Alert Service Bulletin 747-53A2448, Revision 1, dated April 4, 2002, 
except as provided by paragraph (d) of this AD.

Optional Modification and Post-Modification Inspections

    (c) If no crack is found during any inspection required by 
paragraph (a) of this AD, operators may accomplish paragraphs (c)(1) 
and (c)(2) of this AD.
    (1) Do an 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) per Figure 4 or 
7, as applicable, of Boeing Alert Service Bulletin 747-53A2448, 
Revision 1, dated April 4, 2002, except as provided by paragraph (d) 
of this AD. Such modification ends the repetitive inspections 
required by paragraph (a) of this AD.
    (2) At the applicable compliance time and repetitive inspection 
interval specified in Figure 1 of Boeing Alert Service Bulletin 747-
53A2448, Revision 1, dated April 4, 2002, perform detailed and HFEC 
inspections to find cracking of the skin at the upper aft and 
forward corners of the lower lobe cargo door cutout, per Figure 5 of 
the service bulletin. If any crack is found, before the next flight, 
repair per the service bulletin, except as provided by paragraph (d) 
of this AD.

Repair and Modification: Exception

    (d) Where Boeing Alert Service Bulletin 747-53A2448, Revision 1, 
dated April 4, 2002, specifies to contact Boeing for repair or 
modification information: 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 (DER) who 
has been authorized by the Manager, Seattle ACO, to make such 
findings. For a repair method to be approved as required by this 
paragraph, the approval must specifically refer to this AD.

Alternative Methods of Compliance

    (e) 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.


[[Page 42210]]


    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

    (f) 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 June 14, 2002.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-15663 Filed 6-20-02; 8:45 am]
BILLING CODE 4910-13-P