[Federal Register Volume 68, Number 5 (Wednesday, January 8, 2003)]
[Proposed Rules]
[Pages 1017-1020]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-333]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-231-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-400 and -400F 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 747-400 and -
400F series airplanes. This proposal would require initial and, for 
certain airplanes, repetitive inspections of the

[[Page 1018]]

rivets in the forward, top, and side panels of the nose wheel well 
(NWW) for discrepancies; and follow-on inspections and corrective 
action, if necessary. This proposal also provides eventual terminating 
action for the repetitive inspections. This action is necessary to find 
and fix discrepancies of the rivets in the NWW panels, which could 
result in failure of the rivets and consequent reduced structural 
integrity of the panels and rapid depressurization of the airplane. 
This action is intended to address the identified unsafe condition.

DATES: Comments must be received by February 24, 2003.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2001-NM-231-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. 2001-NM-231-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:
    [sbull] 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.
    [sbull] For each issue, state what specific change to the proposed 
AD is being requested.
    [sbull] 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 2001-NM-231-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. 2001-NM-231-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that missing rivet heads 
were found in the side panels of the nose wheel well (NWW) between body 
stations 260 and 340 of the canted pressure bulkhead on certain Boeing 
Model 747-400 and -400F series airplanes. Investigation revealed that 
the rivets were incorrectly heat-treated and were made of 7050 
aluminum, which is susceptible to stress corrosion cracking. Rivets in 
the subject area should be made of 2017 aluminum, which is a more 
durable material. One airplane had 44 discrepant rivets (missing heads, 
incorrectly heat-treated) at random locations on both side panels, 28 
of the rivets were found using a detailed inspection, and 16 were found 
using an indirect conductivity eddy current inspection method. Such 
discrepancies, if not found and fixed, could result in failure of the 
rivets and consequent reduced structural integrity of the NWW panels 
and rapid depressurization of the airplane.

Explanation of Relevant Service Information

    We have reviewed and approved Boeing Alert Service Bulletin 747-
53A2472, including Appendix A, dated June 7, 2001, which describes 
procedures for initial and repetitive detailed inspections and a 
follow-on indirect conductivity eddy current inspection for 
discrepancies (missing rivet heads or incorrectly heat-treated rivets) 
in the forward, top, and side panels of the NWW between fuselage 
stations 260 and 340 of the canted pressure bulkhead; and corrective 
action, if necessary. The corrective action includes the following:
    [sbull] If up to three adjacent rivets with missing heads are 
found, remove the discrepant rivets and install permanent or time 
limited repair fasteners.
    [sbull] If four or more adjacent rivets with missing heads are 
found, remove discrepant rivets and do a high frequency eddy current 
inspection of the web for cracking around the intact fasteners at each 
end of the line of missing rivets.
    [sbull] If web cracking is found, the service bulletin specifies 
contacting the manufacturer for repair instructions.
    [sbull] If no web cracking is found, install permanent or time 
limited repair fasteners.
    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.

Difference Between Service Information and Proposed Rule

    Although the service bulletin specifies that the manufacturer may 
be contacted for disposition of certain repair conditions, this 
proposal would require the repair of those conditions to be done 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.

[[Page 1019]]

Interim Action

    This is considered to be interim action until final action is 
identified, at which time the FAA may consider further rulemaking.

Cost Impact

    There are approximately 43 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 6 airplanes of U.S. registry 
would be affected by this proposed AD.
    It would take approximately 4 work hours per airplane to do the 
proposed detailed inspection, at an average labor rate of $60 per work 
hour. Based on these figures, the cost impact of the detailed 
inspection proposed by this AD on U.S. operators is estimated to be 
$1,440, or $240 per airplane, per inspection cycle.
    It would take approximately 10 work hours per airplane to do the 
proposed indirect conductivity eddy current inspection, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the indirect conductivity eddy current inspection proposed by 
this AD on U.S. operators is estimated to be $3,600, or $600 per 
airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet done any of the proposed requirements of this 
AD action, and that no operator would do 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 2001-NM-231-AD.

    Applicability: Model 747-400 and -400F series airplanes, line 
numbers 1141 through 1183 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 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 discrepancies of the rivets in the nose wheel 
well (NWW) panels, which could result in failure of the rivets and 
consequent reduced structural integrity of the panels and rapid 
depressurization of the airplane, do the following:

Repetitive/Follow-on Inspections/Corrective Action

    (a) Within 6 months after the effective date of this AD: Do a 
detailed inspection of the forward, top, and side panels of the NWW 
for missing rivet heads, between fuselage stations 260 and 340 of 
the canted pressure bulkhead, per Figure 2 of the Work Instructions 
of Boeing Alert Service Bulletin 747-53A2472, including Appendix A, 
dated June 7, 2001.
    (1) If any missing rivet head is found, before further flight, 
replace with a permanent or time limited repair fastener and do the 
actions specified in paragraph (b) of this AD.
    (2) If no missing rivet head is found, before further flight, do 
the actions required by paragraph (c) of this AD, or repeat the 
detailed inspection at least every 6 months until paragraph (c) of 
this AD is done.

    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.''

    (b) If any missing rivet head is found during any inspection 
required by paragraph (a) of this AD: Within 30 days after doing the 
detailed inspection, do an indirect conductivity eddy current 
inspection for discrepant rivets (incorrectly heat-treated) per 
Figure 2 of the Work Instructions of the service bulletin. If any 
discrepant rivet is found, before further flight, replace with a 
permanent or time limited repair fastener as required by paragraph 
(b)(1) or (b)(2) of this AD, as applicable. If no discrepant rivet 
is found, no further action is required by this AD. Replace any time 
limited repair fasteners with permanent fasteners within 24 months 
after installation.
    (1) If up to three adjacent discrepant rivets are found: Before 
further flight, remove the affected rivets and replace with 
permanent or time limited repair fasteners per the Work Instructions 
of the service bulletin.
    (2) If four or more adjacent discrepant rivets are found: Before 
further flight, remove the affected rivets and do a high frequency 
eddy current inspection of the web for cracking around the intact 
fasteners at each end of the line of missing rivets per the Work 
Instructions of the service bulletin.
    (i) If no web cracking is found, before further flight, install 
permanent or time limited repair fasteners per the Work Instructions 
of the service bulletin.
    (ii) If any web cracking is found, 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, the 
approval must specifically reference this AD.

Terminating Action

    (c) For airplanes on which no missing rivet head is found during 
the inspection required by paragraph (a) of this AD: Within 2 years 
after the effective date of this AD, do an indirect conductivity 
eddy current inspection

[[Page 1020]]

for discrepant rivets (incorrectly heat-treated) of the NWW panels 
between fuselage stations 260 and 340 of the canted pressure 
bulkhead per the Work Instructions of Boeing Alert Service Bulletin 
747-53A2472, including Appendix A, dated June 7, 2001.
    (1) If any discrepant rivet is found, before further flight, 
replace with a permanent or time limited repair fastener. Replace 
any time limited repair fasteners with permanent fasteners within 24 
months after installation.
    (2) If no discrepant rivet is found, no further action is 
required by this AD.

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 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 Permit

    (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 done.

    Issued in Renton, Washington, on December 31, 2002.
Kevin Mullin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-333 Filed 1-7-03; 8:45 am]
BILLING CODE 4910-13-P