[Federal Register Volume 72, Number 237 (Tuesday, December 11, 2007)]
[Proposed Rules]
[Pages 70247-70249]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-23955]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-0308; Directorate Identifier 2007-NM-160-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-
100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 
747-400F, and 747SR Series Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Boeing Model 747 airplanes identified above. This proposed 
AD would require modifying the outboard flap track and transmission 
attachments. This proposed AD results from a joint Boeing and FAA 
multi-model study (following in-service trailing edge flap structure 
and drive system events) on the hazards posed by skewing and failed 
flaps. This study identified the safety concerns regarding the 
transmission attachment design and the potential loss of an outboard 
trailing edge flap. We are proposing this AD to prevent certain 
discrepancies associated with this design (for example, a flap skew or 
lateral control asymmetry that can cause collateral damage to adjacent 
hydraulic tubing and subsequent loss of a hydraulic system), which 
could result in the asymmetric flight control limits being exceeded, 
and could adversely affect the airplane's continued safe flight and 
landing.

DATES: We must receive comments on this proposed AD by January 25, 
2008.

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, P.O. Box 3707, Seattle, Washington 98124-
2207.

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: Doug Tsuji, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-
3356; telephone (425) 917-6487; 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-2007-0308; 
Directorate Identifier 2007-NM-160-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

    A report has been completed about a joint Boeing and FAA multi-
model study (following in-service trailing edge flap structure and 
drive system events) on the hazards posed by skewing and failed flaps. 
The study identified safety concerns with the transmission attachment 
design, which does not meet the single failure condition analysis 
criteria. Three bolts attach the transmission to the flap track. The 
fracture of one of the transmission attachment bolts in flight could 
lead to an overload failure of the two remaining bolts and subsequent 
loss of the transmission. In addition, a support housing with an 
undetected fracture could lead to the loss of the transmission. Loss of 
the flap transmission could lead to a flap skew or lateral control 
asymmetry. Loss of a transmission could lead to possible collateral 
damage to adjacent hydraulic tubing and the loss of a hydraulic system. 
A flap skew or asymmetry combined with collateral hydraulic system 
damage could result in the asymmetric flight control limits being 
exceeded, and could adversely affect the airplane's continued safe 
flight and landing.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletins 747-27A2398 and 
747-27A2421, both dated April 19, 2007. The service bulletins describe 
the following procedures for modifying the outboard trailing edge 
flaps, including the following ``airplane work'':
     Replacing the flap tracks and flap transmissions with a 
new configuration (flap tracks and flap transmissions 1, 2, 7, and 8);
     Reversing the bolt direction on the flap track side load 
fitting; and
     Installing new flap track fairing hinge braces. The 
service bulletins describe the following component work:
     Replacing the upper forward and the upper aft flap 
transmission attachment bolt hole bushings;
     Replacing the support housing;
     Machining the track and installing the larger diameter 
bolt hole bushings, at the upper forward and upper aft flap 
transmission attachment locations (flap track assemblies 1 and 8) and 
at the

[[Page 70248]]

upper aft flap transmission attachment location (flap track assemblies 
2 and 7); and
     Replacing the existing support housing with the new 
support housing (flap transmission assemblies 1, 2, 7, and 8).
    The compliance time is 6 years for airplanes known to have fewer 
than 20,000 total flight cycles, and 3 years for all other airplanes.
    Accomplishing the actions specified in the service information is 
intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other airplanes 
of this same type design. For this reason, we are proposing this AD, 
which would require the actions specified in the service information 
described previously.

Costs of Compliance

    There are about 990 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD.

                                                                     Estimated Costs
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                                                                                                                        Number of U.S.-
                             Work hours                               Average labor        Parts           Cost per        registered       Fleet cost
                                                                      rate per hour                        airplane        airplanes
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150................................................................             $80          $80,023          $92,023              141      $12,975,243
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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 have 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 that the 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD and placed it in the AD docket. See the 
ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, 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 Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-0308; Directorate Identifier 2007-NM-
160-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by January 
25, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 747-100, 747-100B, 747-100B 
SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-
400F, and 747SR series airplanes, certificated in any category; as 
identified in Boeing Alert Service Bulletin 747-27A2398 or 747-
27A2421, both dated April 19, 2007.

Unsafe Condition

    (d) This AD results from a joint Boeing and FAA multi-model 
study (following in-service trailing edge flap structure and drive 
system events) on the hazards posed by skewing and failed flaps. 
This study identified the safety concerns regarding the transmission 
attachment design and the potential loss of an outboard trailing 
edge flap. We are issuing this AD to prevent certain discrepancies 
associated with this design (for example, a flap skew or lateral 
control asymmetry that can cause collateral damage to adjacent 
hydraulic tubing and subsequent loss of a hydraulic system), which 
could result in the asymmetric flight control limits being exceeded, 
and could adversely affect the airplane's continued safe flight and 
landing.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Modification

    (f) Do the following, as applicable: At the time specified in 
paragraph 1.E. of Boeing Alert Service Bulletin 747-27A2421 or 747-
27A2398, both dated April 19, 2007, except as provided by paragraph 
(g) of this AD, modify the outboard flap track and transmission 
attachments by doing all actions specified in the Accomplishment 
Instructions of the service bulletin.
    (g) Where Boeing Alert Service Bulletins 747-27A2421 and 747-
27A2398, both dated April 19, 2007, specify compliance times 
relative to the date on the service bulletin, this AD requires 
compliance within the specified compliance time after the effective 
date of this AD.

Parts Installation

    (h) As of the effective date of this AD, no person may install a 
part identified in Table 1 of this AD on any airplane.

[[Page 70249]]



              Table 1.--Parts Prohibited From Installation
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                          Part                               Part No.
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Hinge brace for Tracks 1 and 8.........................       65B15515-1
                                                              65B15515-2
                                                              65B15515-9
                                                             65B15515-10
Hinge brace for Tracks 2 and 7.........................       65B15525-1
                                                              65B15525-2
                                                              65B15525-7
                                                              65B15525-8
                                                              65B17092-1
                                                              65B17092-2
Support assembly for Tracks 1 and 8....................     65B81982-( )
Support assembly for Tracks 2 and 7....................     65B81950-( )
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Alternative Methods of Compliance (AMOCs)

    (i)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (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 appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.

    Issued in Renton, Washington, on November 13, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-23955 Filed 12-10-07; 8:45 am]
BILLING CODE 4910-13-P