
[Federal Register: May 23, 2008 (Volume 73, Number 101)]
[Proposed Rules]               
[Page 30003-30005]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr23my08-12]                         

=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0590; Directorate Identifier 2008-NM-057-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), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: We propose to adopt a new airworthiness directive (AD) for all 
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. 
This proposed AD would require repetitive inspections for cracks or 
fractures of the forward end attachment and the forward lower flange of 
the flap tracks of the trailing edge flaps, and corrective actions if 
necessary. For certain airplanes, this proposed AD would also require 
modifying the fail-safe links of the main carriage. This proposed AD 
results from a detailed structural analysis of the flap attach 
structural and fail-safe components, accomplished as a result of a 
dynamic stability and control analysis, which could not demonstrate 
continued safe flight and landing of the airplane after the loss of a 
trailing edge flap. We are proposing this AD to detect and correct 
cracks or fractures of the primary structural and fail-safe load paths 
of the inboard and outboard trailing edge flaps, which could result in 
the loss of a flap during takeoff or landing, reducing flightcrew 
ability to maintain the safe flight and landing of the airplane.

DATES: We must receive comments on this proposed AD by July 7, 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 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: Gary Oltman, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
917-6443; 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-2008-0590; 
Directorate Identifier 2008-NM-057-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 detailed structural analysis of the flap attach structural and 
fail-safe components, accomplished as a result of a dynamic stability 
and control analysis, could not demonstrate continued safe flight and 
landing of the airplane after the loss of a trailing edge flap. This 
structural analysis showed that additional inspections and 
modifications should be accomplished to prevent the loss of a flap. For 
components where there is a fail-safe load path, the inspections were 
based on finding a fractured component within the fatigue life of the 
fail-safe component of the load path. For the main carriage fail-safe 
link load path, the analysis showed the components were not adequate to 
retain the flap in the case of a fracture of the carriage. These 
conditions, if not corrected, could result in the loss of a flap during 
takeoff or landing, reducing flightcrew ability to maintain the safe 
flight and landing of the airplane.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 747-57A2323, dated 
February 21, 2008. For all airplanes, the service bulletin describes 
procedures for repetitive general visual inspections for cracks or 
fractures of the forward end attachment of the flap tracks, fuse pin, 
and support fitting; repetitive detailed inspections for cracks or 
fractures of the forward lower flange of the flap tracks; and 
corrective actions if necessary. The corrective actions include 
replacing the flap track and the fail-safe strap if any crack or 
fracture is found in a flap track; replacing the fuse pin and fail-safe 
strap if any crack or fracture is found in a fuse pin; and replacing 
the support fitting if any crack or fracture is found in a support 
fitting. If no cracks are found, the general visual inspection is 
repeated during inspection of the flap track forward attachment, and 
after each replacement is done. For Groups 1 through 3 airplanes, the 
service bulletin describes procedures for modifying the fail-safe links 
of the main carriage by replacing the links, pins, and attachment 
hardware. The service bulletin also recommends contacting Boeing for 
repair data if a fractured support fitting is found.
    The compliance time for the general visual inspection is within 
6,000 total flight cycles on the flap track since new, or within 750 
flight cycles, whichever occurs later. If no crack or fracture is 
found, the inspection is repeated at intervals not to exceed 750 flight 
cycles.
    The compliance time for the detailed inspection is within 20,000 
total flight cycles on the flap track since new, or within 1,500 flight 
cycles, whichever occurs later. If no crack or fracture is found, the 
inspection is repeated at

[[Page 30004]]

intervals not to exceed 1,500 flight cycles.
    The compliance time for modifying the fail-safe links of the main 
carriage for Groups 1 through 3 airplanes is within 24 months after the 
date on the service bulletin.

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 same type design. 
This proposed AD would require accomplishing the actions specified in 
the service information described previously, except as discussed under 
``Difference Between the Proposed AD and Service Information.''

Difference Between the Proposed AD and Service Information

    The alert service bulletin specifies to contact the manufacturer 
for instructions on how 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 190 airplanes of 
U.S. registry. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD.

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                     Number of U.S.-
              Action                    Work hours        Average labor          Parts           Cost per product      registered         Fleet cost
                                                          rate per hour                                                 airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Part 1: Inspections..............  4...................             $80  $0..................  $320, per inspection             190  $60,800, per
                                                                                                cycle.                                inspection cycle.
Part 3: Inspections..............  4...................              80  $0..................  $320, per inspection             190  $60,800, per
                                                                                                cycle.                                inspection cycle.
Part 2: Modification for Groups 1- Between 3 and 7.....              80  Between $212 and      Between $452 and                 182  Between $82,264 and
 3 airplanes.                                                             $7,934.               $8,494.                               $1,545,908.
--------------------------------------------------------------------------------------------------------------------------------------------------------

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, 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-2008-0590; Directorate Identifier 2008-NM-
057-AD.

Comments Due Date

    (a) We must receive comments by July 7, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all 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.

Unsafe Condition

    (d) This AD results from a detailed structural analysis of the 
flap attach structural and fail-safe components accomplished as a 
result of a dynamic stability and control analysis, which could not 
demonstrate continued safe flight and landing of the airplane after 
the loss of a trailing edge flap. We are issuing this AD to detect 
and correct cracks or fractures of the primary structural and fail-
safe load paths of the inboard and outboard trailing edge flaps, 
which could result in the loss of a flap during takeoff or landing, 
reducing flightcrew ability to maintain the safe flight and landing 
of the airplane.

Compliance

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

Repetitive Inspections/Corrective Actions

    (f) For all airplanes: Except as provided by paragraph (h) of 
this AD; at the applicable times specified in paragraph 1.E. of 
Boeing Alert Service Bulletin 747-57A2323, dated February 21, 2008, 
inspect for cracks or fractures of the forward end attachment and

[[Page 30005]]

the forward lower flange of the flap tracks of the trailing edge 
flaps by doing all the actions specified in Parts 1 and 3 of the 
Accomplishment Instructions of the service bulletin; except as 
provided by paragraph (i) of this AD. Do all applicable corrective 
actions before further flight. Repeat the applicable inspection at 
the applicable time specified in paragraph 1.E. of the service 
bulletin.

Modification of Fail Safe Links of Main Carriage

    (g) For Groups 1, 2, and 3 airplanes: Within 24 months after the 
effective date of this AD, replace the fail-safe links, pins, and 
attachment hardware in accordance with Part 2 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-57A2323, dated 
February 21, 2008.

Exception to Compliance Times

    (h) Where Boeing Alert Service Bulletin 747-57A2323, dated 
February 21, 2008, specifies counting the compliance time from ``* * 
* the date on this service bulletin,'' this AD requires counting the 
compliance time from the effective date of this AD.

Exception to Corrective Actions

    (i) If any fractured support fitting is found during any 
inspection required by this AD, and Boeing Alert Service Bulletin 
747-57A2323, dated February 21, 2008, specifies to contact Boeing 
for appropriate action: Before further flight, repair using a method 
approved in accordance with the procedures specified in paragraph 
(j) of this AD.

Alternative Methods of Compliance (AMOCs)

    (j)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, ATTN: Gary Oltman, Aerospace Engineer, Airframe Branch, ANM-
120S, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; 
telephone (425) 917-6443; fax (425) 917-6590; has the authority to 
approve AMOCs for this AD, if requested using 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.
    (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 May 16, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E8-11565 Filed 5-22-08; 8:45 am]

BILLING CODE 4910-13-P
