[Federal Register Volume 66, Number 76 (Thursday, April 19, 2001)]
[Proposed Rules]
[Pages 20114-20116]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-9668]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-346-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100 and -200 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 747-100 and -
200 series airplanes. This proposal would require repetitive 
inspections for cracking of the station 800 frame assembly, and repair, 
if necessary. This action is necessary to find and fix fatigue cracks 
that could extend and fully sever the frame, which could result in 
development of skin cracks that could lead to rapid depressurization of 
the airplane. This action is intended to address the identified unsafe 
condition.

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-346-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-346-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-346-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-346-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports that operators have found fatigue 
cracks in the strap and inner chord angle at the station 800 frame, 
between stringers 14 and 18, on certain Boeing Model 747-100 and -200 
series airplanes. The cracks can initiate at certain fastener holes. 
Fatigue cracks in this area, if not found and fixed, can extend and 
fully sever the frame. If the frame is severed, skin cracks could 
occur, which could result in rapid depressurization of the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-53A2451, including Appendix A, dated October 5, 2000, which 
describes procedures for repetitive inspections for cracking of the 
station 800 frame assembly between stringers 14 and 18. The procedures 
involve removal of fasteners; detailed visual, surface high frequency 
eddy current (HFEC), and open hole HFEC inspections, as applicable, for 
cracking of the inner chord strap, angles, and exposed web at station 
800; and installation of new or serviceable fasteners. If any cracking 
is detected, the service bulletin says to contact Boeing for repair 
instructions.

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 Service Bulletin and Proposed AD

    Operators should note that, although the service bulletin specifies 
that the manufacturer may be contacted for repair instructions, this 
proposed AD would require repair according to a method approved by the 
FAA, or according to data meeting the type certification basis of the 
airplane approved by a Boeing Company Designated Engineering 
Representative

[[Page 20115]]

who has been authorized by the FAA to make such findings.

Cost Impact

    There are approximately 258 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 139 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take up to 14 work 
hours per airplane to accomplish the proposed inspections, and that the 
average labor rate is $60 per work hour. Based on these figures, the 
cost impact of the proposed AD on U.S. operators is estimated to be as 
much as $116,760, or $840 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-346-AD.

    Applicability: Model 747-100 and -200 series airplanes, as 
listed in Boeing Alert Service Bulletin 747-53A2451, including 
Appendix A, dated October 5, 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 (c) 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 fatigue cracks of the station 800 frame assembly 
that could extend and fully sever the frame, which could result in 
development of skin cracks that could lead to rapid depressurization 
of the airplane, accomplish the following:

Repetitive Inspections

    (a) Do detailed visual, surface high frequency eddy current 
(HFEC), and open hole HFEC inspections, as applicable, for cracking 
of the station 800 frame assembly (including the inner chord strap, 
angles, and exposed web) between stringers 14 and 18, according to 
Boeing Alert Service Bulletin 747-53A2451, including Appendix A, 
dated October 5, 2000. Except as provided by paragraph (b) of this 
AD, do the inspection at the applicable time specified in Table 1 
below, and repeat the inspections thereafter at least every 3,000 
flight cycles: Table 1 is as follows:

                       Table 1.--Compliance Times
------------------------------------------------------------------------
  Total flight cycles as of the effective       Do the inspection in
             date of this AD--              paragraph (a) at this time--
------------------------------------------------------------------------
Fewer than 19,000.........................  Before the accumulation of
                                             19,000 total flight cycles,
                                             or within 1,500 flight
                                             cycles after the effective
                                             date of this AD, whichever
                                             comes later.
19,000 or more but 24,250 or fewer........  Within 1,500 flight cycles
                                             or 12 months after the
                                             effective date of this AD,
                                             whichever comes first.
24,251 or more............................  Within 750 flight cycles or
                                             12 months after the
                                             effective date of this AD,
                                             whichever comes first.
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    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.''

Adjustments to Compliance Time: Cabin Differential Pressure

    (b) For the purposes of calculating the compliance threshold and 
repetitive interval for the actions required by paragraph (a) of 
this AD, 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

    (c) If any cracking is detected during any inspection required 
by paragraph (a) of this AD, before further flight, repair the 
cracking according to a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA; or according to 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 approval letter must specifically 
reference 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

[[Page 20116]]

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 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 April 12, 2001.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-9668 Filed 4-18-01; 8:45 am]
BILLING CODE 4910-13-U