Airworthiness Directives; Boeing Model 747 Airplanes and Model 767 Airplanes Equipped With General Electric CF6-80C2 and CF6-80A Series Engines, 18721-18722 [E8-7153]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 73, Number 67 (Monday, April 7, 2008)]
[Proposed Rules]
[Pages 18721-18722]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E8-7153]



[[Page 18721]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0402; Directorate Identifier 2007-NM-165-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Airplanes and Model 
767 Airplanes Equipped With General Electric CF6-80C2 and CF6-80A 
Series 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 airplanes and Model 767 airplanes. This 
proposed AD would require revising the airplane flight manual to advise 
the flightcrew to use certain procedures during descent in certain 
icing conditions. This proposed AD results from reports of several in-
flight engine flameouts, including multiple dual engine flameout events 
and one total power loss event, in ice-crystal icing conditions. We are 
proposing this AD to ensure that the flightcrew has the proper 
procedures to follow in certain icing conditions. These certain icing 
conditions could cause a multiple engine flameout during flight without 
the ability of the engines to be relit, and consequent forced landing 
of the airplane.

DATES: We must receive comments on this proposed AD by May 22, 2008.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to https://
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 https://
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: Margaret Langsted, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6500; 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-2008-0402; 
Directorate Identifier 2007-NM-165-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 https://
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 indicating that there have been several 
in-flight engine flameout events, including one dual event, on Model 
767 airplanes and four dual events on Model 747 airplanes, in ice-
crystal icing conditions at altitudes between 13,000 and 36,000 feet 
during descent. These airplanes were equipped with General Electric 
(GE) CF6-80C2 series engines. Each flameout event was in or near 
convective weather with ice-crystal icing; this type of icing does not 
appear on radar due to its low reflectivity, and neither the airplane 
ice detector nor visual indications indicate the presence of icing 
conditions. Therefore, it is often undetected by the flightcrew. These 
conditions can cause ice crystals to accumulate in the core flow path 
of the engine during low-power conditions, such as idle or idle 
descent. The accumulated ice sheds during throttle increase and is 
ingested into the engine, causing the combustor to flameout resulting 
in an in-flight flameout and potential damage to the high pressure 
compressor due to ice impact. The GE CF6-80C2 and CF6-80A series 
engines models have similar compressor designs.
    Activating the engine anti-ice increases the flameout margin and 
reduces the potential for multiple engine flameouts by increasing bleed 
flow and idle speed. Engine anti-ice also assists with relighting the 
engines by turning on the igniters on airplanes that are not equipped 
with autorelight. However, in several of the subject engine flameout 
events, the engine anti-ice was already on when the engines flamed out. 
In each flameout event, the engines relit and continued to operate 
normally for the remainder of the flight.
    The requirement to activate the engine anti-ice prior to descent in 
visible moisture with total air temperature less than 10 [deg]Celsius 
(C) and greater than -40 [deg]C already exists for airplanes that are 
not equipped with a primary in-flight ice detection system, which is 
designed to automatically activate wing anti-ice and engine anti-ice 
when the airplane is in icing conditions. However, the primary in-
flight ice detection system does not detect ice-crystal icing; 
therefore, the engine anti-ice would not be activated during these 
icing encounters. There is no requirement to activate engine anti-ice 
at temperatures below -40 [deg]C, and this proposed AD would require 
activation of engine anti-ice at temperatures below -40 [deg]C.
    This condition, if not corrected, could result in a multiple engine 
flameout during flight without the ability of the engines to be relit, 
and consequent forced landing of the airplane.

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 revising the airplane flight 
manual (AFM) to advise the flightcrew to use certain procedures during 
descent in certain icing conditions.

Interim Action

    We consider this proposed AD interim action. If final action is 
later

[[Page 18722]]

identified, we might consider further rulemaking then.

Costs of Compliance

    There are about 1,064 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.-
                      Action                           Work hours     Average labor        Parts           Cost per        registered       Fleet cost
                                                                      rate per hour                        airplane        airplanes
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AFM revision......................................               1              $80               $0              $80              340          $27,200
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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-2008-0402; Directorate Identifier 2007-NM-
165-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by May 22, 
2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 747 airplanes and Model 767 
airplanes, certified in any category, equipped with General Electric 
CF6-80C2 or CF6-80A series engines.

Unsafe Condition

    (d) This AD results from reports of several in-flight engine 
flameouts, including multiple dual engine flameout events and one 
total power loss event, in ice-crystal icing conditions. We are 
issuing this AD to ensure that the flightcrew has the proper 
procedures to follow in certain icing conditions. These certain 
icing conditions could cause a multiple engine flameout during 
flight without the ability of the engines to be relit, and 
consequent forced landing of the airplane.

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.

Airplane Flight Manual (AFM) Revision

    (f) Within 14 days after the effective date of this AD, revise 
the Limitations Section of the Boeing 747 or 767 AFM, as applicable, 
to include the following statement. This may be done by inserting a 
copy of this AD into the AFM.
    ``Prior to descent in visible moisture and TAT less than 10 
[deg]C, including SAT less than -40 [deg]C, nacelle anti-ice switch 
must be in the ON position.''

    Note 1:
    When a statement identical to that in paragraph (f) of this AD 
has been included in the general revisions of the AFM, the general 
revisions may be inserted into the AFM, and the copy of this AD may 
be removed from the AFM.

Alternative Methods of Compliance (AMOCs)

    (g)(1) The Manager, Seattle Aircraft Certification Office, 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 March 27, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E8-7153 Filed 4-4-08; 8:45 am]
BILLING CODE 4910-13-P