Document ID: FAA-2009-0135-0002
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: Boeing Model 747-400 and 747-400D Series Airplanes
Posted Date: 2009-02-18T05:00Z

[Federal Register: February 18, 2009 (Volume 74, Number 31)]
[Proposed Rules]
[Page 7573-7575]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr18fe09-17]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2009-0135; Directorate Identifier 2008-NM-170-AD]
RIN 2120-AA64

Airworthiness Directives; Boeing Model 747-400 and 747-400D
Series Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for
certain Boeing Model 747-400 and 747-400D series airplanes. This
proposed AD would require repetitive inspections to detect cracks in
the floor panel attachment fastener holes of the Section 41 upper deck
floor beam upper chords, and related investigative and corrective
actions if necessary. This proposed AD results from reports of cracks
found in the Section 41 upper deck floor beam upper chords. We are
proposing this AD to detect and correct cracks in these chords, which
could become large and cause the floor beams to become severed and
result in rapid decompression or reduced controllability of the
airplane.

DATES: We must receive comments on this proposed AD by April 6, 2009.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://
www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.
    For service information identified in this proposed AD, contact
Boeing Commercial Airplanes, Attention: Data & Services Management,
P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-
544-5000, extension 1, fax 206-766-5680; e-mail me.boecom@boeing.com;
Internet https://www.myboeingfleet.com. You may review copies of the
referenced service information at the FAA, Transport Airplane
Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information
on the availability of this material at the FAA, call 425-227-1221 or
425-227-1152.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Management Facility
between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays. The AD docket contains this proposed AD, the regulatory
evaluation, any comments received, and other information. The street
address for the Docket Office (telephone 800-647-5527) is in the
ADDRESSES section. Comments will be available in the AD docket shortly
after receipt.

FOR FURTHER INFORMATION CONTACT: Ivan Li, Aerospace Engineer, Airframe
Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind
Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6437;
fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or
arguments about this proposed AD. Send your comments to an address
listed under the ADDRESSES section. Include ``Docket No. FAA-2009-0135;
Directorate Identifier 2008-NM-170-AD'' at the beginning of your
comments. We specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of this proposed AD. We
will consider all comments received by the closing date and may amend
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://
www.regulations.gov, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact we
receive about this proposed AD.

Discussion

    We have received reports of cracks found in the floor panel
attachment fastener holes of the Section 41 upper deck floor beam upper
chords on three different Boeing Model 747-400D series airplanes, which
had accumulated 24,053, 24,783, and 25,631 total flight cycles. Similar
cracks were also found on the Model 747-400 fatigue test airplane.
Cracks in these chords that are not found and repaired could become
large and cause the floor beams to become severed. This can lead to
large deflection of the upper deck floor; and cause damage to the
adjacent body skin, frames, and stringers. Because flight-critical wire
bundles and control cables are routed through cutouts in the upper deck
floor beams, a large deflection of the upper deck floor could result in
damage to wire bundles and unintended inputs to the flight control
cables, which could result in reduced controllability of the airplane.
If multiple adjacent floor beams are severed, the result could be rapid
decompression or reduced controllability.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 747-53A2688,
datedAugust 21, 2008. The service bulletin describes procedures for
repetitive inspections for fatigue cracks of the floor panel attachment
fastener holes in the Section 41 upper deck floor beam upper chords.
The inspection type depends on the means of access (whether gained from
above or below) and repair/modification condition. The inspection
procedures described are (1) open-hole high frequency eddy current
(HFEC) inspections of the floor panel

[[Page 7574]]

attachment fastener holes in the upper chords, or (2) surface HFEC
inspections of the forward and aft horizontal flanges of the upper
chords at floor panel attachment fastener holes, preceded by
modification of the clipnuts for the floor panel attachment fasteners.
    For airplanes with no crack, the service bulletin provides optional
procedures for modifying (by oversizing) the floor panel attachment
holes, which would extend the compliance time for the initiation of the
repetitive inspections.
    The service bulletin specifies repairing cracks per the service
bulletin or contacting Boeing for repair instructions. For certain
conditions, the repair procedures provided in the service bulletin
include oversizing affected holes, doing an open-hole HFEC inspection
for cracks, and repeating the oversizing and inspection procedures
until no crack indications are found. The service bulletin also
provides procedures for installing repair straps and clips for certain
other conditions.
    The compliance time for the initial inspection is before 20,000
total flight cycles on the floor beam upper chords, within 1,000 flight
cycles after the effective date of the service bulletin, or within
2,000 or 6,000 flight cycles (depending on the inspection type used)
since the last Supplemental Structural Inspection Document (SSID)
inspection (the SSID inspections are required by AD 2004-07-22 R1,
amendment 39-15326 (73 FR 1052, January 7, 2008), whichever occurs
latest. Cracks must be repaired before further flight. The threshold
for the initiation of the repetitive inspection depends on the most
recent inspection type used and repair/modification status, and ranges
from 2,000 to 15,000 flight cycles. The intervals for the repetitive
inspections depend on the inspection type and repair/modification
status, and range from 2,000 to 6,000 flight cycles.

FAA's Determination and Requirements of This Proposed AD

    We are proposing this AD because we evaluated all relevant
information and determined the unsafe condition described previously is
likely to exist or develop in other products of the(se) same type
design(s). This proposed AD would require accomplishing the actions
specified in the service information described previously, except as
discussed below.

Differences Between Proposed Rule and Service Bulletin

    The service bulletin specifies to contact the manufacturer for
instructions to repair certain conditions, but this proposed AD would
require repairing those conditions in one of the following ways:
     Using a method that we approve; or
     Using data that meet the certification basis of the
airplane, and that have been approved by an Authorized Representative
for the Boeing Commercial Airplanes Delegation Option Authorization
Organization whom we have authorized to make those findings.

Costs of Compliance

    We estimate that this proposed AD would affect 53 airplanes of U.S.
registry. The following table provides the estimated costs for U.S.
operators to comply with this proposed AD.

                                                                 Table--Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                               Number of U.S.-
            Action                      Work hours          Average labor        Parts       Cost per product    registered            Fleet cost
                                                            rate per hour                                         airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inspection....................  48 or 50.................             $80  None............  $3,840 or $4,000              53  Up to $212,000 per
                                                                                              per inspection                    inspection cycle.
                                                                                              cycle.
--------------------------------------------------------------------------------------------------------------------------------------------------------

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. ``Subtitle VII: Aviation
Programs,'' describes in more detail the scope of the Agency's
authority.
    We are issuing this rulemaking under the authority described in
``Subtitle VII, Part A, Subpart III, Section 44701: General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
rulemaking action.

Regulatory Findings

    We determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD 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.
    For the reasons discussed above, I certify 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. 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.
    You can find our regulatory evaluation and the estimated costs of
compliance in the AD Docket.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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. The FAA amends Sec.  39.13 by adding the following new AD:

Boeing: Docket No. FAA-2009-0135; Directorate Identifier 2008-NM-
170-AD.

Comments Due Date

    (a) We must receive comments by April 6, 2009.

[[Page 7575]]

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 747-400 and 747-400D series
airplanes, certificated in any category; as identified in Boeing
Alert Service Bulletin 747-53A2688, dated August 21, 2008.

Subject

    (d) Air Transport Association (ATA) of America Code 53:
Fuselage.

Unsafe Condition

    (e) This AD results from reports of cracks found in the Section
41 upper deck floor beam upper chords. We are issuing this AD to
detect and correct cracks in these chords, which could become large
and cause the floor beams to become severed and result in rapid
decompression or reduced controllability of the airplane.

Compliance

    (f) Comply with this AD within the compliance times specified,
unless already done.

Inspections and Corrective Actions

    (g) Except as required by paragraphs (h) and (i) of this AD: At
the applicable times in paragraph 1.E., ``Compliance,'' of Boeing
Alert Service Bulletin 747-53A2688, dated August 21, 2008, do an
inspection (open-hole or surface high frequency eddy current), to
detect cracks in the floor panel attachment fastener holes of the
Section 41 upper deck floor beam upper chords, and do applicable
related investigative and corrective actions, by accomplishing all
the applicable actions specified in the Accomplishment Instructions
of the service bulletin. Repeat the inspections thereafter at the
applicable times specified in paragraph 1.E., ``Compliance,'' of the
service bulletin.
    (h) If any crack is found during any inspection required by
paragraph (g) of this AD, and Boeing Alert Service Bulletin 747-
53A2688, dated August 21, 2008, specifies to contact Boeing for
appropriate action: Before further flight, repair the crack using a
method approved in accordance with the procedures specified in
paragraph (j) of this AD.
    (i) Where Boeing Alert Service Bulletin 747-53A2688, dated
August 21, 2008, specifies a compliance time after the date on the
service bulletin, this AD requires compliance within the specified
compliance time after the effective date of this AD.

Alternative Methods of Compliance (AMOCs)

    (j)(1) The Manager, Seattle Aircraft Certification Office (ACO),
FAA, has the authority to approve AMOCs for this AD, if requested
using the procedures found in 14 CFR 39.19. Send information to
ATTN: Ivan Li, Aerospace Engineer, Airframe Branch, ANM-120S, FAA,
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW.,
Renton, Washington 98057-3356; telephone (425) 917-6437; fax (425)
917-6590.
    (2) To request a different method of compliance or a different
compliance time for this AD, follow the procedures in 14 CFR 39.19.
Before using any approved AMOC on any airplane to which the AMOC
applies, notify your principal maintenance inspector (PMI) or
principal avionics inspector (PAI), as appropriate, or lacking a
principal inspector, your local Flight Standards District Office.
The AMOC approval letter must specifically reference this AD.
    (3) An AMOC that provides an acceptable level of safety may be
used for any repair required by this AD, if it is approved by an
Authorized Representative for the Boeing Commercial Airplanes
Delegation Option Authorization Organization who has been authorized
by the Manager, Seattle ACO, to make those findings. For a repair
method to be approved, the repair must meet the certification basis
of the airplane, and the approval must specifically refer to this
AD.

    Issued in Renton, Washington, on February 5, 2009.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E9-3386 Filed 2-17-09; 8:45 am]

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