Document ID: FAA-2008-0402-0016
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: Boeing Co. Model 747 Airplanes and Model 767 Airplanes Equipped with General Electric Model CF6-80C2 or CF6-80A Series Engines
Posted Date: 2011-07-26T04:00Z

[Federal Register Volume 76, Number 143 (Tuesday, July 26, 2011)]
[Rules and Regulations]
[Pages 44458-44461]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-18747]

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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; 
Amendment 39-16760; AD 2011-16-02]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Model 747 Airplanes 
and Model 767 Airplanes Equipped With General Electric Model CF6-80C2 
or CF6-80A Series Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for the 
products listed above. This AD requires revising the airplane flight 
manual (AFM) to advise the flightcrew to use certain procedures during 
descent in certain icing conditions. This AD was prompted by 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 with the potential inability to restart the engines, and 
consequent forced landing of the airplane.

DATES: This AD is effective August 30, 2011.

ADDRESSES: 

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 AD, the regulatory evaluation, 
any comments received, and other information. The address for the 
Docket Office (phone: 800-647-5527) is Document Management Facility, 
U.S. Department of Transportation, Docket Operations, M-30, West 
Building Ground Floor, Room W12-140, 1200

[[Page 44459]]

New Jersey Avenue, SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Rebel Nichols, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; phone: 
425-917-6509; fax: 425-917-6590; e-mail: rebel.nichols@faa.gov.

SUPPLEMENTARY INFORMATION: 

Discussion

    We issued a supplemental notice of proposed rulemaking (SNPRM) to 
amend 14 CFR part 39 to include an airworthiness directive (AD) that 
would apply to the specified products. That SNPRM published in the 
Federal Register on August 4, 2010 (75 FR 46868). The original NPRM (73 
FR 18721, April 7, 2008) proposed to require revising the airplane 
flight manual (AFM) to advise the flightcrew to use certain procedures 
during descent in certain icing conditions. The SNPRM proposed to 
revise the original NPRM by revising the text of the proposed AFM 
revision.

Other Relevant Rulemaking

    Related AD 2010-16-03, Amendment 39-16379 (75 FR 47203, August 5, 
2010), requires similar actions for Model MD-11 and MD-11F airplanes, 
certificated in any category, equipped with General Electric (GE) CF6-
80C2 series engines. These airplanes have been determined to be subject 
to the identified unsafe condition addressed in this AD.

Comments

    We gave the public the opportunity to participate in developing 
this AD. The following presents the comments received on the proposal 
and the FAA's response to each comment.

Request To Withdraw SNPRM

    While GE Aviation (GE) recognized that the FAA has the ultimate 
responsibility in evaluating and declaring the existence of an unsafe 
condition, GE disagreed that an unsafe condition is likely to exist and 
refuted the FAA's basis for its determination. GE pointed out that 
there has never been a Model CF6-80C2 engine that has failed to relight 
rapidly, and that this fact is significant in that this is different 
from the field experience for some other turbofan engines of different 
design. GE pointed out that Note 11 of FAA-approved Type Certificate 
Data Sheet E13NE for Model CF6-80A engines includes the following 
statement: ``* * * momentary N1 excursions below 40%, not to 
exceed 60 seconds durations, are permissible for approach and landing 
operation below 10,000 feet pressure altitude.'' For these reasons, GE 
contended that the data prove that a forced landing is extremely 
improbable, and, while the proposed changes in the SNPRM will provide 
additional margin against rare inclement weather-related flameouts, GE 
did not believe that the proposed changes should be mandated.
    GE also agreed that, while there might be variation in operational 
costs among operators and a relatively small cost impact on an 
individual per-flight basis, there is a cumulative impact when applied 
to the more than 1,000 airplanes in the worldwide fleet. GE estimated 
that the proposed procedures would result in an environmental burden of 
tens of millions of pounds of carbon dioxide per year (estimate assumes 
an additional 50 gallons of fuel per flight x 20 pounds of carbon 
dioxide per gallon of fuel x 600,000 flights a year x an estimated 10 
percent of flight descents in visible moisture). So, while the bleed 
does add some projected event rate benefit in certain circumstances, GE 
believes the extremely improbable rate of dual engine flameouts coupled 
with the adverse environmental impact outweigh the benefits of the 
proposed AFM procedure.
    From these statements, we infer that GE requests that we withdraw 
the NPRM. We do not agree. We have evaluated the unsafe condition and 
find that sufficient data exist to demonstrate that certain icing 
conditions that cause the engine flameout could also cause engine 
damage that potentially would prevent an engine from relighting. The 
condition could exist on all of an airplane's engines, resulting in a 
forced landing. We have determined that an unsafe condition exists, and 
the appropriate vehicle for correcting an unsafe condition is an AD. 
These safety concerns must be addressed, even in light of the 
environmental impact. We have not changed the AD regarding this issue.

Request To Clarify Additional Flameout Event on Model 747 Airplane

    GE referred to the ``Actions Since Original NPRM Was Issued'' 
section of the SNPRM, particularly the report of another significant 
flameout event on a Model 747 airplane. GE believes the mentioned event 
was actually a temporary power loss event that occurred in 2007, and 
that no more recent multi-engine inclement-weather-related events have 
occurred on a CF6-powered Model 747 airplane.
    We agree to clarify. Any time a transport category airplane 
experiences power loss events resulting from a common cause on multiple 
engines, we consider it a significant event. Flameout events do cause 
power loss, but can also cause adverse engine operation, which can 
include engine stall and power rollback. Certain icing conditions that 
lead to flameouts could also cause compressor damage, preventing the 
engine from relighting. Loss of a single engine affects other aircraft 
systems--hydraulic, pressurization, and electrical--all of which are 
supplied by engine-driven components. There are backup systems, but 
relighting an engine in flight can still be difficult because of the 
distracting secondary effects of losing power. A multi-engine flameout 
compounds these factors. In November 2007, the airplane in the subject 
report sustained three multi-engine flameouts, including, at one point, 
a three-engine flameout. This multi-engine flameout event developed 
into much more than a simple power loss event. We have not changed the 
AD in this regard.

Request To Allow Use of Automatic Activation of Anti-Ice Systems

    UPS asserted that the proposed AFM revision does not address 
airplanes with automatic anti-ice systems. UPS confirmed that a portion 
of their fleet is equipped with automatic nacelle and wing anti-ice 
systems, and questioned whether setting these systems in the ``auto'' 
position will satisfy the requirement to have nacelle and wing anti-ice 
systems on during descent.
    From these statements, we infer that UPS is requesting that we 
revise the SNPRM to allow operators with airplanes equipped with 
automatic anti-ice systems to use the ``auto'' setting in lieu of 
manually activating the anti-ice systems. We do not agree. Automatic 
anti-ice systems or primary in-flight ice detection systems have been 
effective in detecting typical icing conditions, but they do not have 
the capability to detect ice-crystal icing. Therefore, the anti-ice 
systems would not be activated during these icing encounters, and would 
not provide an adequate level of safety in lieu of manual anti-ice 
activation in ice-crystal icing conditions. We have made no change to 
the final rule in this regard.

Requests To Revise AFM Procedure To Qualify Weather Conditions

    Delta Airlines (Delta) requested that we revise the proposed AFM 
procedure to add the qualifier, ``when near convective weather systems, 
including thunderstorms.'' Japan Airlines (JAL) also requested that we 
include a similar statement. Delta stated that it

[[Page 44460]]

understands that the risk of flameout due to ice-crystal icing occurs 
only when the airplane is near convective weather systems, and 
explained that its flightcrews can recognize nearby convective weather. 
Delta contended that revising the AFM procedure to allow flightcrews to 
activate nacelle anti-ice when convective weather is near would prevent 
the unnecessary increase in fuel burn and overuse of engine anti-ice 
when engine flameouts due to ice crystals are not factors. JAL reasoned 
that, because operating the anti-ice systems increases the crew 
workload and fuel consumption, the weather conditions that require use 
of the anti-ice systems should be limited to areas where there is 
technical benefit of preventing engine flameout.
    We do not agree. Ice-crystal icing does typically occur in or near 
convective weather. However, this type of icing does not appear on 
radar due to its low reflectivity, and neither the airplane ice 
detectors nor visual indications indicate the presence of this type of 
icing condition. Service experience has demonstrated that flightcrews 
are not always able to differentiate between ice-crystal icing that 
causes engine flameout and other types of visible moisture that 
typically do not lead to engine flameouts. Therefore, relying on 
flightcrews to recognize the necessary weather conditions might not 
provide an adequate level of safety. We have not changed the final rule 
in this regard.
    Additionally, in regard to JAL's statement that anti-ice system 
operation increases fuel consumption, we have determined that the 
additional fuel burn necessitated by the AFM procedure would not be 
significant enough to warrant removal of the requirement to use anti-
ice under certain conditions. However, as we explain under ``Requests 
to Allow Deactivation of Anti-ice Systems When Icing No Longer 
Exists,'' we have revised the procedure to allow anti-icing systems to 
be deactivated when the subject icing conditions no longer exist. This 
allowance will further reduce any additional fuel burn caused by the 
use of the anti-ice system.

Request for Additional Revision of AFM Procedure

    JAL further requested that we revise the proposed AFM procedure to 
remove ``the wing anti-ice operation below 22,000 ft and above TAT 10 
degree C.'' JAL explained that, in Asia, where most of the engine 
flameout events occurred, the total air temperature (TAT) at 22,000 
feet is around 8 [deg]Celsius (C) according to standard calculations, 
and that the ground temperature in southern Asia is estimated to be 32 
[deg]C. JAL further explained that static air temperature (SAT) 
decreases 2 degrees per every 1,000 feet; therefore, the SAT at 22,000 
feet is -12 [deg]C. Therefore, JAL states that, considering +20 [deg]C 
ram effect in descent speed, TAT at 22,000 feet is approximately 8 
[deg]C. For these reasons, and because the flightcrew would be required 
to turn the anti-ice systems on and off in a very short time, JAL 
stated it believes that the use of wing anti-ice systems should not be 
included in the proposed AFM procedure, especially given the additional 
crew workload and the probability of a flameout.
    We agree that clarification is necessary. It is not our intent to 
require activation of the wing anti-ice system at temperatures above 
TAT 10 [deg]C. The required AFM procedure specified in this AD requires 
use of the anti-ice systems only when in visible moisture and a TAT of 
less than 10 [deg]C. As explained under ``Requests to Allow 
Deactivation of Anti-ice Systems When Icing No Longer Exists,'' we have 
revised the required AFM procedure to allow anti-icing systems to be 
turned off when the specified icing conditions are no longer present or 
anticipated. No further change to this AD is necessary in this regard.

Requests To Allow Deactivation of Anti-Ice Systems When Icing No Longer 
Exists

    Boeing and GE requested that we revise the proposed AFM procedure 
to allow anti-icing systems to be deactivated when the subject icing 
conditions no longer exist. Boeing and GE contended that this change 
would provide clarity and consistency with related rulemaking on Model 
MD-11 airplanes.
    We agree. We have determined that there is no additional benefit to 
having the nacelle and wing anti-ice switched on once icing conditions 
are no longer present or anticipated. Therefore, we have revised the 
AFM text provided in paragraph (g) of this final rule accordingly.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
the AD with the changes described previously.
    We also determined that these changes will not increase the 
economic burden on any operator or increase the scope of the AD.

Interim Action

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

                                                 Estimated Costs
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                                                                                       Number  of
                                               Average                    Cost per        U.S.-
           Action              Work hours    labor rate       Parts       airplane     registered    Fleet cost
                                              per hour                                  airplanes
----------------------------------------------------------------------------------------------------------------
AFM revision................            1           $85            $0           $85           340       $28,900
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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.

[[Page 44461]]

Regulatory Findings

    This AD will not have federalism implications under Executive Order 
13132. This AD will 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 this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979),
    (3) Will not affect intrastate aviation in Alaska, and
    (4) 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.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

2011-16-02 The Boeing Company: Amendment 39-16760; Docket No. FAA-
2008-0402; Directorate Identifier 2007-NM-165-AD.

Effective Date

    (a) This AD is effective August 30, 2011.

Affected ADs

    (b) None.

Applicability

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

Subject

    (d) Air Transport Association (ATA) of America Code 30: Ice and 
rain protection.

Unsafe Condition

    (e) This AD was prompted by 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 with the potential inability to restart the engines, and 
consequent forced landing of the airplane.

Compliance

    (f) 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

    (g) 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 reducing thrust for 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. At or below 22,000 ft, 
wing anti-ice selector must be in the ON position. When these icing 
conditions (visible moisture and TAT less than 10 [deg]C, including 
SAT less than -40 [deg]C) are no longer present or anticipated, 
place the nacelle and wing anti-ice selectors in the OFF (or AUTO) 
position.''

    Note 1: When a statement identical to that in paragraph (g) 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.

Special Flight Permits

    (h) Special flight permits, as described in Section 21.197 and 
Section 21.199 of the Federal Aviation Regulations (14 CFR 21.197 
and 21.199), may be issued to operate the airplane to a location 
where the requirements of this AD can be accomplished provided the 
operational requirements defined in the Limitations Section of the 
AFM are used if icing is encountered.

Related Information

    (i) For more information about this AD, contact Rebel Nichols, 
Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98057-3356; phone: 425-917-6509; fax: 425-917-6590; e-
mail: rebel.nichols@faa.gov.

Material Incorporated by Reference

    (j) None.

    Issued in Renton, Washington, on July 14, 2011.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-18747 Filed 7-25-11; 8:45 am]
BILLING CODE 4910-13-P