[Federal Register Volume 72, Number 107 (Tuesday, June 5, 2007)]
[Proposed Rules]
[Pages 31001-31003]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-10757]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-28352; Directorate Identifier 2007-NM-037-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-200B, 747-300, 747-
400, 747-400D, and 747-400F Series Airplanes Equipped With General 
Electric CF6-80C2 Engines

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 747-200B, 747-300, 747-400, 747-400D, and 747-
400F series airplanes. This proposed AD would require repetitive 
inspections of the left- and right-hand flipper door assemblies of the 
engine core cowls for migrated pins and damaged flipper doors, and 
corrective actions if necessary. Modification of the hinge assemblies 
terminates the repetitive inspections. This proposed AD results from 
two reports of missing flipper doors for the engine core cowls. We are 
proposing this AD to detect and correct migrated hinge pins and damaged 
flipper doors, which could allow the flipper door to fall off, 
resulting in the potential for an engine fire to propagate into the 
flammable leakage zone of the strut and for the amount of fire 
extinguishing agent reaching the fire to be diluted, and subsequent 
uncontained fire in the engine strut.

DATES: We must receive comments on this proposed AD by July 20, 2007.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590.
     Fax: (202) 493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for the service information identified in this 
proposed AD.

FOR FURTHER INFORMATION CONTACT: Sulmo Mariano, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6501; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed in the ADDRESSES section. Include the docket number ``FAA-2007-
28352; Directorate Identifier 2007-NM-037-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments received by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of 
that Web site, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You may review DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
may visit http://dms.dot.gov.

Examining the Docket

    You may examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Management Facility office (telephone (800) 647-
5227) is located on the plaza level of the Nassif Building at the DOT 
street address stated in the ADDRESSES section. Comments will be 
available in the AD docket shortly after the Docket Management System 
receives them.

Discussion

    We have received two reports of missing flipper doors for the 
engine core cowls on Boeing Model 747 series airplanes equipped with 
General Electric CF6-80C2 engines. Investigation into the cause of the 
missing flipper doors revealed that hinge pins for the flipper doors 
were not secured correctly, and the vibration from the engine core 
cowls caused the hinge pins to migrate, allowing the flipper doors to 
fall off.
    When the engine core cowl is opened during normal operation, the 
flipper door opens to provide clearance for the hinge fittings. When 
the engine core cowl is closed, the flipper door is clamped underneath 
the strut seal, forming a continuous strut firewall. If a flipper door 
is missing, it creates a 1-inch by 5-inch hole in the strut firewall. 
According to requirements of the master minimum equipment list, an 
airplane cannot depart with a missing flipper door.
    This condition, if not corrected, could result in the potential for 
an engine fire to propagate into the flammable leakage zone of the 
strut and for the amount of fire extinguishing agent reaching the fire 
to be diluted, and subsequent uncontained fire in the engine strut.

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletin 747-71-
2310, dated October 13, 2005. The service bulletin describes procedures 
for repetitively inspecting the left- and right-hand flipper door 
assemblies for migrated hinge pins and damaged flipper doors, and 
corrective actions if necessary. The corrective actions include 
replacing any damaged flipper door with a new or serviceable flipper 
door, and modifying the hinge assemblies if necessary. The modification 
includes shortening the hinge pin and peening (deforming) both ends of 
the hinge assembly to capture the pin. Modifying the hinge assemblies 
eliminates the need for the repetitive inspections. Accomplishing the 
actions specified in the service information is intended to adequately 
address the unsafe condition.
    The Boeing service bulletin refers to Rohr Service Bulletin TBC/
80C2-NAC-71-035, dated October 10, 2005, as an additional source of 
service information for inspecting hinge pins of the flipper doors, 
inspecting and replacing damaged flipper doors, and modifying the hinge 
assemblies of the flipper doors.

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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 accomplishing the actions specified in the service 
information described previously.

Costs of Compliance

    There are about 297 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
                                                  Work     Average              Cost per      U.S.-
                     Action                       hours   labor rate   Parts    airplane    registered                     Fleet cost
                                                           per hour                         airplanes
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Inspection of flipper door assemblies, per            1          $80      $0     $80, per           42  $3,360, per inspection cycle.
 inspection cycle.                                                             inspection
                                                                                    cycle
Modification of hinge assemblies, if                  1          $80      $0          $80     Up to 42  Up to $3,360.
 accomplished.
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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-2007-28352; Directorate Identifier 2007-NM-
037-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by July 20, 
2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 747-200B, 747-300, 747-400, 
747-400D, and 747-400F series airplanes, certificated in any 
category, equipped with General Electric CF6-80C2 engines.

Unsafe Condition

    (d) This AD results from two reports of missing flipper doors 
for the engine core cowl. We are issuing this AD to detect and 
correct migrated hinge pins and damaged flipper doors, which could 
allow the flipper door to fall off, resulting in the potential for 
an engine fire to propagate into the flammable leakage zone of the 
strut and for the amount of fire extinguishing agent reaching the 
fire to be diluted, and subsequent uncontained fire in the engine 
strut.

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.

Inspection of the Flipper Door Assemblies

    (f) Within 24 months after the effective date of this AD: Do a 
general visual inspection for migrated hinge pins and damaged 
flipper doors of the left- and right-hand flipper door assemblies of 
the engine core cowls, and do all applicable corrective actions, by 
accomplishing all the actions specified in the Accomplishment 
Instructions of Boeing Special Attention Service Bulletin 747-71-
2310, dated October 13, 2005. Do all applicable corrective actions 
before further flight. Repeat the inspection thereafter at intervals 
not to exceed 18 months for that flipper door assembly, until doing 
the modification specified in paragraph (g) of this AD.

    Note 1: Boeing Special Attention Service Bulletin 747-71-2310, 
dated October 13, 2005, refers to Rohr Service Bulletin TBC/80C2-
NAC-71-035, dated October 10, 2005, as an additional source of 
service information for accomplishing the actions specified in 
paragraph (f) of this AD.

Terminating Action for Repetitive Inspections

    (g) Modifying a hinge assembly of a flipper door assembly of the 
engine core cowls in accordance with the Accomplishment Instructions 
of Boeing Special Attention Service Bulletin 747-71-2310, dated 
October 13, 2005, terminates the repetitive inspection requirements 
of this AD for that hinge assembly.

Parts Installation

    (h) As of the effective date of this AD, no person may install, 
on any airplane, a hinge assembly, part number 224-2335-69, for the 
flipper door of the engine core cowl unless

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it has been modified in accordance with the requirements of 
paragraph (g) of this AD.

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 May 25, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-10757 Filed 6-4-07; 8:45 am]
BILLING CODE 4910-13-P