Document ID: FAA-2008-0403-0009
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: McDonnell Douglas Corp. Model MD-11 and MD-11F Airplanes Equipped with General Electric CF6-80C2 Series Engines
Posted Date: 2010-08-05T04:00Z

[Federal Register: August 5, 2010 (Volume 75, Number 150)]
[Rules and Regulations]               
[Page 47203-47207]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr05au10-12]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0403; Directorate Identifier 2007-NM-166-AD; 
Amendment 39-16379; AD 2010-16-03]
RIN 2120-AA64

 
Airworthiness Directives; McDonnell Douglas Corporation Model MD-
11 and MD-11F Airplanes Equipped With General Electric CF6-80C2 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 certain 
Model MD-11 and MD-11F airplanes. This AD requires revising the 
airplane flight manual to advise the flightcrew to use certain 
procedures during descent in certain icing conditions. This AD results 
from reports of several in-flight engine flameouts, including multiple 
dual engine flameout events, 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 September 9, 2010.

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

[[Page 47204]]

other information. The address for the Docket Office (telephone 800-
647-5527) is the Document Management Facility, U.S. Department of 
Transportation, Docket Operations, M-30, West Building Ground Floor, 
Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Samuel Lee, Aerospace Engineer, 
Propulsion Branch, ANM-140L, FAA, Los Angeles Aircraft Certification 
Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; 
telephone (562) 627-5262; fax (562) 627-5210.

SUPPLEMENTARY INFORMATION: 

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to include an airworthiness directive (AD) that would apply to 
certain Model MD-11 and MD-11F airplanes. That NPRM was published in 
the Federal Register on April 7, 2008 (73 FR 18719). That NPRM proposed 
to require revising the airplane flight manual (AFM) to advise the 
flightcrew to use certain procedures during descent in certain icing 
conditions.

Other Relevant Proposed Rulemaking

    NPRM, Docket No. FAA-2008-0402, Directorate Identifier 2007-NM-165-
AD (73 FR 18721, April 7, 2008), proposes to require similar actions 
for Model 747 airplanes and Model 767 airplanes, certified in any 
category, equipped with General Electric Model CF6-80C2 or CF6-80A 
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. We considered the comments received.

Support for the NPRM

    The Air Line Pilots Association, International supports the intent 
and language of the NPRM. The National Transportation Safety Board 
(NTSB), based on the success of similar AFM requirements to address 
this unsafe condition on Hawker Beechcraft Corporation Model 400, 400A, 
and 400T series airplanes and Model MU-300 airplanes, supports the 
adoption of the proposed requirements.

Request for FAA To Actively Pursue Research To Develop a Permanent 
Solution

    The NTSB notes that the NPRM is intended as interim action, and 
points out that it has issued Safety Recommendation A-06-59, dated 
August 25, 2006. In this safety recommendation the NTSB asked the FAA 
to ``* * * work with engine and airplane manufacturers and other 
industry personnel as well as the appropriate international 
airworthiness authorities to actively pursue research to develop an ice 
detector that would alert pilots to internal engine icing and require 
that it be installed on new production turbojet engines, as well as 
retrofitted to existing turbojet engines.'' Therefore, the NTSB hopes 
the FAA pursues research in concert with the multinational Aircraft 
Icing Research Alliance that might develop an ice detector to alert 
flightcrews to the accretion of ice crystals on internal engine 
surfaces, so that flightcrews can take the appropriate actions.
    We partially agree with the commenter's request. We agree that the 
General Electric (GE) CF6-80C2 series engine needs to be modified to 
mitigate the risk of flameouts caused by ice crystal accretion. 
However, at this time, we do not agree to pursue research to develop an 
ice detector that would alert flightcrews to the internal engine icing, 
or with requiring manufacturers to install ice detectors internal to 
the engines. In addition, no such designs have been proposed to the 
FAA. Instead, for future designs, we are developing rulemaking to show 
acceptable engine operation in an ice crystal environment. For engines 
that currently demonstrate a susceptibility to ice crystals, we are 
working with manufacturers to develop engine design changes to make 
engines more robust during ice crystal accumulation and shedding 
encounters. We will continue to provide feedback to the NTSB through 
the established process for addressing safety recommendations. For this 
AD, if different methods to address the unsafe condition are developed, 
under the provisions of paragraph (h) of this AD, we will consider 
requests for approval of an AMOC if sufficient data are submitted to 
substantiate that the method would provide an acceptable level of 
safety. No change to the AD is necessary in this regard.

Request To Require Demonstration of Non-Susceptibility in Future 
Designs

    The NTSB states that it hopes the FAA will require future engine 
designs to demonstrate that they will not be susceptible to the 
accretion of ice crystals on internal surfaces. The NTSB points out 
that this request is in keeping with information provided to the NTSB 
by an FAA icing expert during a briefing with the Safety Board.
    From these statements, we infer that the NTSB is requesting that we 
revise the NPRM to include a statement of our intent to require 
manufacturers to demonstrate that future engine designs are not 
susceptible to the accretion of ice crystals. We partially agree. We 
agree that current FAA regulations addressing engine and airplane icing 
do not apply to the ice crystal environment; therefore, we are working 
with the aviation industry to develop appropriate regulations that 
address operation in an ice crystal environment. As we determine the 
necessary requirements to address this issue, we will consider 
additional rulemaking. We do not agree to revise this AD to include a 
statement regarding future regulations that have not yet been 
determined. No change to the AD is necessary in this regard.

Request To Withdraw the NPRM

    GE acknowledges that a small number of inclement weather or 
significant weather system encounters have resulted in short-duration 
multiple engine power loss. GE points out that these few events 
occurred out of 14 million flights over 20 years of total service 
experience on the Model CF6-80C2 series engine. GE states that a forced 
landing resulting from one of these in-flight ice-crystal icing events 
is extremely improbable (including demonstrated relight performance). 
Therefore, GE asserts that the proposed condition does not meet the 
definition of ``unsafe condition,'' as defined by FAA Advisory Circular 
39-8, ``Continued Airworthiness Assessments of Powerplant and Auxiliary 
Power Unit Installations of Transport Category Airplanes,'' dated 
September 8, 2003.
    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 the environment 
that causes the engine flameout would likely 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. The advisory circular referenced by the commenter merely 
provides guidance. We have determined that an unsafe condition exists, 
and the appropriate vehicle for correcting an unsafe condition is an 
AD. We have not changed the AD regarding this issue.

Request To Revise Wording of the Unsafe Condition

    Boeing proposes that we revise the wording of the unsafe condition 
from, ``These certain icing conditions could cause a multiple engine 
flameout during

[[Page 47205]]

flight without the ability of the engines to be relit * * *'' to 
``These certain icing conditions may cause a multiple engine flameout 
during flight, with the potential inability to restart the engines * * 
*.'' Boeing asserts that the wording in the NPRM overly conveys the 
likelihood of not being able to restart the engine(s) after flameout. 
While the possibility exists, Boeing confirms that all engines involved 
in all of the flameout events to date have been restarted in flight 
with subsequent normal landings.
    We agree. We acknowledge that none of the flameout events on this 
engine model to date have resulted in a forced landing due to the 
inability to restart the engines. We agree that the inability to 
restart the engines following flameout is possible, not probable. 
Therefore, we have revised the unsafe condition statement in the 
Summary section and paragraph (e) of this AD (specified as paragraph 
(d) of the NPRM) as proposed by Boeing.

Requests To Revise Wording in the Discussion Section of the NPRM

    Boeing proposes that we revise the Discussion section of the NPRM 
to state that there have been seven engine flameout events, not six. 
Boeing states that it has received seven reports of flameout events on 
Model MD-11 airplanes due to ice-crystal icing conditions.
    We acknowledge that Boeing has received seven reports, instead of 
the six specified in the NPRM. However, the Discussion section of the 
NPRM is not restated in the final rule; therefore, no change to the AD 
is necessary in this regard.
    GE suggests that we revise the wording of the Discussion section of 
the NPRM to remove the word ``core,'' or, if that is not acceptable, to 
change ``core flow path'' to ``booster and core flow path.'' GE points 
out that the term ``core'' can be interpreted to mean just the high-
pressure spool portion of a turbofan.
    We partially agree. We do not agree with GE's suggestion to remove 
the word ``core'' from the Discussion section. We do agree that the 
phrase ``booster and core flow path'' is more accurate; however, 
because the Discussion section of the NPRM is not restated in this AD, 
there is no need to revise the AD in this regard.
    GE suggests that we revise the Discussion section of the NPRM to 
change the word ``usually'' to ``often'' in the following sentence: 
``Therefore, it [ice-crystal icing] is usually undetected by the 
flightcrew.'' GE states that this change would make the NPRM consistent 
with a similar NPRM (Directorate Identifier 2007-NM-165-AD, Docket FAA-
2008-0402 (73 FR 18721, April 7, 2008)), which addresses the same 
unsafe condition on certain Model 747 and 767 airplanes.
    From this statement, we infer that GE is requesting that we revise 
the Discussion section of the NPRM to clarify that ice-crystal icing is 
often undetected by the flightcrew, not usually undetected. We 
partially agree. We agree that the wording change suggested by GE would 
make this AD consistent with a similar NPRM that addresses the same 
unsafe condition on certain Model 747 and 767 airplanes. However, as 
previously noted, the Discussion section in the NPRM is not restated in 
this AD, therefore, there is no need to revise the AD in this regard.

Requests To Revise the Costs of Compliance Section of the NPRM

    GE suggests that there should be an operational cost of compliance 
included in the proposed Costs of Compliance provided in the NPRM. GE 
states that, while increasing engine off-take or bleed does provide 
additional margin against flameout, doing so requires somewhat 
increased fuel burn. GE believes the proposed procedure would be 
required on a significant percentage of flights.
    Federal Express (FedEx) believes that the total cost of the NPRM 
has either not been fully considered, or has not been properly 
communicated. FedEx asserts that the cost of using wing and tail anti-
ice increases fuel burn and exposes the airplane to additional 
reliability risks associated with increased use of the anti-ice system, 
while only providing a small incremental amount of effectiveness. FedEx 
also states that it estimates the increased fuel consumption to be 40 
pounds for a descent from flight level (FL) 400 to landing.
    From these statements, we infer that GE and FedEx are requesting 
that we revise the Costs of Compliance section of the NPRM to provide 
an operational cost for increased fuel burn necessitated by use of the 
proposed AFM procedure. We do not agree. The cost information in AD 
actions describes only the direct costs of the specific action required 
by the AD: an AFM revision in this case. The estimated cost of this 
action represents the time necessary to perform only the actions 
actually required by this AD. We recognize that, in doing the actions 
required by an AD, operators might incur operational costs in addition 
to the direct costs. The cost analysis in AD rulemaking actions, 
however, typically does not include incidental or operational costs 
such as the time required for planning or other administrative actions, 
and, in this case, possible additional fuel costs. Those costs, which 
might vary significantly among operators, are almost impossible to 
calculate. Additionally, we have determined that the additional fuel 
burn necessitated by the AFM procedure would be insignificant. However, 
as we explain under ``Request to Revise the Proposed AFM Text,'' we 
have revised the procedure to allow the ANTI-ICE switches to be placed 
in the OFF position when icing conditions are no longer present or 
anticipated. This allowance will further reduce any additional fuel 
burn caused by the use of the anti-ice system. We have not changed the 
Costs of Compliance section of this AD in this regard.

Request To Include Alternative AFM Requirements

    FedEx recommends that we revise the NPRM to allow alternative AFM 
requirements based on the full authority digital engine control (FADEC) 
electronic control unit (ECU) installed software version. FedEx states 
that GE has documented six flameout events suspected to be a result of 
ice-crystal accretion. FedEx points out that GE Service Bulletin 73-21-
07, Engine fuel and control--Electronic Control Unit Introduction of 
Software Version 8.3.K (8322), was introduced to improve the flameout 
margin in ice-crystal conditions. FedEx explains that this software 
change will create new engine control configurations with enhanced 
variable bypass valve (VBV) scheduling logic for inclement weather, and 
will change the scheduling of the VBVs at high altitude to increase ice 
extraction from the booster-core flowpath transition to the fan exit 
stream. FedEx believes there have been no suspected flameout events on 
airplanes using the combination of engine anti-ice and ECU software 
version 8.3.K on Model MD-11s, and indicates that it is upgrading its 
fleet to ECU software version 8.3.K in accordance with AD 2007-22-07, 
Amendment 39-15243 (72 FR 60227, October 24, 2007), applicable to GE 
CF6-80C2D1F turbofan engines. Therefore, FedEx proposes that airplanes 
with ECU software version 8.3.J or previous should follow the AFM 
requirement proposed in the NPRM, and airplanes with software version 
8.3.K or subsequent should be allowed to follow alternative AFM 
requirements. FedEx provides suggested wording for an alternative AFM 
requirement.
    We do not agree to revise this AD to allow alternative AFM 
requirements based on the installed software version. Based on a recent 
multiple engine flameout incident on a Model 747-400

[[Page 47206]]

airplane equipped with CF6-80C2B1F engines and ECU software equivalent 
to the version 8.3.K, we have determined that ECU software version 
8.3.K alone will not necessarily provide an adequate margin of safety 
against engine flameout in all environments. We note that the nacelle 
anti-ice had been switched on prior to engine flameout. Increasing the 
bleed flow and engine idle speed by placing the ENG, WING, and TAIL 
ANTI-ICE switches in the ON position will provide additional margin for 
engine flameout. We have not revised the AD in this regard.

Request To Remove Part of the AFM Requirement

    FedEx requests that additional justification be made available to 
support the proposed AFM requirement to use wing and tail anti-ice 
systems. FedEx states that both its flight operations and engineering 
staffs agree that increasing the flameout margin to buffer against 
possible core shedding of ice-crystal accretion is an important 
requirement, and fully support activation of the ENG IGN OVRD switch 
and engine anti-ice as effective means of reducing flameouts. However, 
FedEx feels strongly that part of the proposed AFM requirement is of 
limited value and might not be justifiable. FedEx asserts that 
selection of wing anti-ice would result in a small or incremental 
increase in core temperature, while increasing fuel flow and 
unnecessarily exposing the airplane to additional reliability risks. 
FedEx further notes that the NTSB, in its comments to the NPRM, made no 
mention of wing and tail anti-ice systems being part of the successful 
recommendations on Model 400A airplanes.
    We do not agree to remove the requirement to use wing and tail 
anti-ice. As discussed previously, despite having the nacelle anti-ice 
switched on, a Model 747-400 airplane experienced a multiple engine 
flameout. Therefore, the use of nacelle anti-ice alone is not 
sufficient to prevent a multiple engine flameout. Increasing the bleed 
flow and engine idle speed by placing the ENG, WING, and TAIL ANTI-ICE 
switches in the ON position will provide additional margin against 
engine flameout. We have not revised the AD in this regard.

Request To Revise the Proposed AFM Text

    Boeing proposes that we revise the proposed AFM text provided in 
the NPRM as follows:

    Prior to reducing thrust for descent, when icing conditions 
(defined by visible moisture in the air and TAT is 6 Deg C or below) 
are present, the ENG IGN OVRD switch and the ENG, WING, and TAIL 
ANTI-ICE switches must be placed in the ON position. When icing 
conditions are no longer present or anticipated, place the ENG IGN 
OVRD switch and the ENG, WING, and TAIL ANTI-ICE switches in the OFF 
position.

Boeing states that this AFM text provides additional procedural 
information, as noted in the current Interim Operating Procedures for 
icing conditions that exist or are anticipated prior to descent.
    We agree that the AFM text changes suggested by Boeing do provide 
helpful procedural information. We have also determined that there is 
no additional benefit to having the engine, wing, and tail 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 AD (specified in paragraph (f) of the NPRM) to include the 
supplemental procedural information provided by Boeing, and to allow 
engine, wing, and tail anti-ice to be switched off once icing 
conditions are no longer present or anticipated.

Explanation of Additional Paragraph in This AD

    We have added a new paragraph (d) to this AD to provide the Air 
Transport Association (ATA) of America subject code 30: Ice and rain 
protection. This code is added to make this AD parallel with other new 
AD actions. We have reidentified subsequent paragraphs accordingly.

Explanation of Additional Change Made to the AD

    We have revised this AD to identify the legal name of the 
manufacturer as published in the most recent type certificate data 
sheet for the affected airplane models.

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.

Explanation of Change to Costs of Compliance

    Since issuance of the original NPRM, we have increased the labor 
rate used in the Costs of Compliance from $80 per work-hour to $85 per 
work-hour. The Costs of Compliance information, below, reflects this 
increase in the specified hourly labor rate.

Costs of Compliance

    There are about 118 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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                        Number of U.S.-
                      Action                           Work hours     Average labor        Parts           Cost per        registered       Fleet cost
                                                                      rate per hour                        airplane        airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
AFM revision......................................               1              $85               $0              $85               70           $5,950
--------------------------------------------------------------------------------------------------------------------------------------------------------

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

[[Page 47207]]

products identified in this rulemaking action.

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), 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.

Adoption of the Amendment

0
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 AD:

2010-16-03 McDonnell Douglas Corporation: Amendment 39-16379. Docket 
No. FAA-2008-0403; Directorate Identifier 2007-NM-166-AD.

Effective Date

    (a) This airworthiness directive (AD) is effective September 9, 
2010.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to McDonnell Douglas Corporation Model MD-11 
and MD-11F airplanes, certified in any category, equipped with 
General Electric CF6-80C2 series engines.

Subject

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

Unsafe Condition

    (e) This AD results from reports of several in-flight engine 
flameouts, including multiple dual engine flameout events, 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 McDonnell Douglas MD-11/MD-11F AFM 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 when icing conditions 
(defined by visible moisture in the air and TAT is 6 [deg]C or 
below) are present, the ENG IGN OVRD switch and the ENG, WING, and 
TAIL ANTI-ICE switches must be placed in the ON position. When icing 
conditions are no longer present or anticipated, place the ENG IGN 
OVRD switch and the ENG, WING, and TAIL ANTI-ICE switches in the OFF 
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.

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Los Angeles Aircraft Certification Office 
(ACO), FAA, has the authority to approve AMOCs for this AD, if 
requested using the procedures found in 14 CFR 39.19. Send 
information to ATTN: Samuel Lee, Aerospace Engineer, Propulsion 
Branch, ANM-140L, FAA, Los Angeles Aircraft Certification Office, 
3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone 
(562) 627-5262; fax (562) 627-5210.
    (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 principal maintenance inspector (PMI) or 
principal avionics inspector (PAI), as appropriate, or lacking a 
principal inspector, your local Flight Standards District Office. 
The AMOC approval letter must specifically reference this AD.

Material Incorporated by Reference

    (i) None.

    Issued in Renton, Washington on July 16, 2010.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2010-19156 Filed 8-4-10; 8:45 am]
BILLING CODE 4910-13-P