[Federal Register Volume 74, Number 31 (Wednesday, February 18, 2009)]
[Proposed Rules]
[Pages 7573-7575]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-3386]


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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 [email protected]; 
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
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Inspection....................  48 or 50.................             $80  None............  $3,840 or $4,000              53  Up to $212,000 per
                                                                                              per inspection                    inspection cycle.
                                                                                              cycle.
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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]
BILLING CODE 4910-13-P