DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[4910-13-P] 

[Docket No. FAA-2014-0521; Directorate Identifier 2014-NE-11-AD; Amendment 

39-18104; AD 2015-04-02] 

RIN 2120-AA64 

Airworthiness Directives; CFM International S.A. Turbofan Engines 

AGENCY: Federal Aviation Administration (FAA), DOT. 

ACTION: Final rule. 

SUMMARY: We are adopting a new airworthiness directive (AD) for all CFM 

International S.A. (CFM) CFM56-7B series turbofan engines. This AD was prompted by 

a dual engine thrust instability event that resulted in the overspeed and in-flight shutdown 

(IFSD) of one engine. This AD requires modification of the engine by removing full 

authority digital engine control (FADEC) software, version 7.B.V4 or earlier, installed in 

the electronic engine controls (EECs) on CFM56-7B engines. We are issuing this AD to 

prevent a thrust instability event, which could lead to overspeed and IFSD of one or more 

engines, loss of thrust control, damage to the engine, and damage to the airplane. 

DATES: This AD is effective [INSERT DATE 35 DAYS AFTER DATE OF 

PUBLICATION IN THE FEDERAL REGISTER]. 

ADDRESSES: For service information identified in this AD, contact CFM International 

Inc., Aviation Operations Center, 1 Neumann Way, MID Room 285, Cincinnati, OH 

45125; phone: 877-432-3272; fax: 877-432-3329; email: geae.aoc@ge.com. You may 

view this service information at the FAA, Engine & Propeller Directorate, 12 New 

England Executive Park, Burlington, MA. For information on the availability of this 

material at the FAA, call 781-238-7125. It is also available on the Internet at 

http://www.regulations.gov by searching for and locating Docket No. FAA-2014-0521 . 
Examining the AD Docket 

You may examine the AD docket on the Internet at http://www.regulations.gov by 

searching for and locating Docket No. F AA-20 14-0521; 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 New 

Jersey Avenue SE., Washington, DC 20590. 

FOR FURTHER INFORMATION CONTACT: Kyle Gustafson, Aerospace Engineer, 

Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England 

Executive Park, Burlington, MA 01803; phone: 781-238-7183; fax: 781-238-7199; email: 

kyle.gustafson@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Discussion 

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by 

adding an AD that would apply to all CFM CFM56-7B series turbofan engines. The 

NPRM published in the Federal Register on October 2, 2014 (79 FR 59467). The NPRM 

was prompted by reports of dual-engine thrust instability events on CFM56-7B turbofan 

engines that resulted in overspeed and IFSD of one engine. These resulted from waterborne contamination of the fuel being supplied to the engine which had an adverse effect 

on the response of the fuel metering valve (FMV) in the hydro-mechanical unit (HMU). 

CFM has modified its F ADEC software to compensate for compromised fuel within the 

HMU and improved the response of the FMV, thereby mitigating these thrust instability 

events. The NPRM proposed to require modification of the engine by removing F ADEC 

software, version 7.B.V4 or earlier, installed in the EECs on CFM56-7B engines. We are 

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issuing this AD to prevent a thrust instability event, which could lead to overspeed and 

IFSD of one or more engines, loss of thrust control, damage to the engine, and damage to 

the airplane. 

Comments 

We gave the public the opportunity to participate in developing this AD. The 

following presents the comments received on the NPRM (79 FR 59467, October 2, 2014) 

and the FAA's response to each comment. 

Request to Change Emphasis from Software Removal to Software Installation 

Delta Air Lines (DAL) and American Air Lines (AAL) requested that we change 

wording in the AD to emphasize installation of an eligible software standard rather than 

removal of the ineligible software standard. They suggested that we add this sentence to 

compliance paragraph (e): "Within 6 months ofthe effective date of this AD, modify the 

engine by installing FADEC software version 7.B.W, released by CFM Service Bulletins 

73-0203 and 73-0204, or later approved software versions." DAL and AAL state that the 

Boeing 737NG Aircraft Maintenance Manual does not contain a removal step but rather 

guides how to overwrite previous software with eligible software. 

We disagree. The purpose of this AD is to require removal of software standard 

7.B.V4, or earlier, to correct the unsafe condition. Overwriting a previously installed 

software standard with a software standard eligible for installation is an acceptable 

method for removing an affected software standard. We did not change this AD. 

Request to Require Use of Software EEC Software Standard 7.B.W or Later 

DAL and AAL requested that we revise paragraph (h)(2) ofFAA AD 2012-05-02 

(77 FR 20511 , April 5, 20 12) ("AD 20 12-05-02") to state that EEC software standard 

7 .B. W or later is required. AD 2012-05-02 requires inspection and modification to the 

Boeing 737NG thrust reversers, and also requires, in paragraph (h)(2), installation of 

software standard 7.B.R3 on affected engines. Since AD 2012-05-02 was issued, new 

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versions of software have been released, requiring alternative methods of compliance 

(AMOCs) to allow installation of versions later than software standard 7.B.R3. The 

requested change to AD 2012-05-02 would bring AD 2012-05-02 and this AD into 

agreement on the required airplane configuration. 

We disagree. The current version ofthe software standard, 7.B.W, also addresses 

the thrust reverser unsafe condition and is approved as an AMOC for AD 2012-05-02. 

We did not change this AD. 

Request to Change Description of the Unsafe Condition 

The Boeing Company (Boeing) and CFM requested that we change the wording 

of the unsafe condition to "We are proposing this AD to mitigate characteristics of a 

thrust instability event; without mitigation, thrust instability events could potentially lead 

to engine overspeed and IFSD of one or more engines, loss of thrust control, and damage 

to the airplane." The commenters state that the EEC cannot prevent the occurrence of the 

events, but it can effectively mitigate the characteristics of the events. 

We disagree. While the work to prevent the root cause of fuel contamination 

continues, the purpose of the FAD EC software and this AD is to prevent the events 

described in the unsafe condition. We did not change this AD. 

Request to Change Wording in the Description Paragraph 

CFM and Boeing requested that we change the wording of two sentences in the 

Description paragraph to "These resulted from water-borne contamination ofthe fuel 

being supplied to the engine which had an adverse effect on the response of the FMV in 

the HMU. CFM has modified its FADEC software to compensate for compromised fuel 

within the HMU and improve the response of the fuel control valve, thereby mitigating 

these thrust instability events. " 

We agree. We changed the wording ofthe two sentences in the Description 

paragraph to be more correct and accurate. 

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Request to Clarify a Sentence in the Relevant Service Information Paragraph 

Boeing requested, for clarity, that in the Relevant Service Information paragraph 

of the preamble we add the words "post 7.B.V4" to describe the FADEC software. 

Boeing requested that the changed sentence read: "The SBs describe the procedures for 

the introduction of new FADEC software, post 7.B.V4, for the EECs." 

We disagree. The information in this AD provides the necessary information for 

compliance. No additional clarification is required. Furthermore, the Relevant Service 

Information paragraph, which appeared in the preamble ofthe NPRM (79 FR 59467, 

October 2, 2014), does not appear in this AD. We did not change this AD. 

Request that We Correct Our References to the FADEC Software Standard 

CFM requested that we change all references to the software standard throughout 

this AD from "7BV4" to "7.B.V4" because that is the correct way to reference the 

software standard. 

We agree. We changed all references to the software standard throughout this AD 

to the correct nomenclature. 

Request to Add a Table Specifying the Software Versions to Remove 

Boeing requested that for clarity we include in this AD a table that would show 

the software versions, by part number, that should be removed as a result of this AD. 

We disagree. The information in this AD provides the necessary information for 

compliance. No additional clarification is required. We did not change this AD. 

Additional Changes 

In our review of the NPRM, we found that we failed to include the prohibition 

against operating any aircraft configured with one engine with F ADEC software version 

7.B.V4 or earlier, installed, and the other engine with an eligible FADEC software 

version installed. This prohibition is in SB CFM Service Bulletin (SB) No. CFM56-7B 

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SIB 73-0203, dated June 9, 2014 and CFM No. SB CFM56-7B SIB 73-0204, dated June 

9, 2014. We added the prohibition to this AD. 

Agreement with the Proposed AD 

One anonymous commenter expressed agreement with this AD. 

Conclusion 

We reviewed the relevant data, considered the comments received, and 

determined that air safety and the public interest require adopting this AD with the 

changes described previously. We have determined that these minor changes: 

• Are consistent with the intent that was proposed in the NPRM (79 FR 

59467, October 2, 2014) for correcting the unsafe condition; and 

• Do not add any additional burden upon the public than was already 

proposed in the NPRM (79 FR 59467, October 2, 2014). 

We also determined that these changes will not increase the economic burden on 

any operator or increase the scope of this AD. 

Costs of Compliance 

We estimate that this AD would affect about 2,921 engines installed on airplanes 

of U.S. registry. We also estimate that it would take about 1 hour per engine to comply 

with this AD. The average labor rate is $85 per hour. Parts cost is zero. Based on these 

figures, we estimate the cost of this AD on U.S. operators to be $248,285. 

Authority for this Rulemaking 

Title 49 ofthe United States Code specifies the FAA's authority to issue rules on 

aviation safety. Subtitle I, section 1 06, describes the authority of the FAA Administrator. 

Subtitle VII: Aviation Programs, describes in more detail the scope ofthe 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 

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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 

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 to the extent that it justifies making 

a regulatory distinction, 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 

1. The authority citation for part 39 continues to read as follows: 

Authority: 49 U.S.C. 1 06(g), 40113 , 44701. 

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§ 39.13 [Amended] 

2. The FAA amends § 3 9.13 by adding the following new airworthiness directive 

(AD): 

2015-04-02 CFM International S.A.: Amendment 39-18104; Docket 

No. FAA-2014-0521; Directorate Identifier 2014-NE-11-AD. 

(a) Effective Date 

This AD is effective [INSERT DATE 35 DAYS AFTER DATE OF 

PUBLICATION IN THE FEDERAL REGISTER]. 

(b) Affected ADs 

None. 

(c) Applicability 

This AD applies to all CFM International S.A. (CFM) CFM56-7B series turbofan 

engmes. 

(d) Unsafe Condition 

This AD was prompted by a dual engine thrust instability event that resulted in 

the overspeed and in-flight shutdown (IFSD) of one engine. We are issuing this AD to 

prevent a thrust instability event, which could lead to overspeed and IFSD of one or more 

engines, loss of thrust control, damage to the engine, and damage to the airplane. 

(e) Compliance 

(1) Comply with this AD within the compliance times specified, unless already 

done. 

(2) Within 6 months after the effective date of this AD, modify the engine by 

removing full authority digital engine control (F ADEC) software, version 7 .B. V 4 or 

earlier, installed in the electronic engine control (EEC). 

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(3) Do not return to service any aircraft configured with one engine with F ADEC 

software, version 7.B.V 4 or earlier, installed, and the other engine with an eligible 

F ADEC software version, installed. 

(f) Alternative Methods of Compliance (AMOCs) 

The Manager, Engine Certification Office, FAA, may approve AMOCs to this 

AD. Use the procedures found in 14 CFR 39.19 to make your request. You may email 

your request to: ANE-AD-AMOC@faa.gov. 

(g) Related Information 

(1) For more information about this AD, contact Kyle Gustafson, Aerospace 

Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New 

England Executive Park, Burlington, MA 01803; phone: 781-238-7183 ; fax: 781-238-

7199; email: kyle.gustafson@faa.gov. 

(2) CFM Service Bulletin (SB) No. CFM56-7B SIB 73-0203 , dated June 9, 2014, 

and CFM No. SB CFM56-7B SIB 73-0204, dated June 9, 2014, which are not 

incorporated by reference in this AD, can be obtained from CFM using the contact 

information in paragraph (g)(3) of this AD. 

(3) For service information identified in this AD, contact CFM International Inc., 

Aviation Operations Center, 1 Neumann Way, MID Room 285, Cincinnati, OH 45125 ; 

phone: 877-432-3272; fax: 877-432-3329; email: geae.aoc@ge.com. 

(4) You may view this service information at the FAA, Engine & Propeller 

Directorate, 12 New England Executive Park, Burlington, MA. For information on the 

availability of this material at the FAA, call (781) 23 8-7125. 

(h) Material Incorporated by Reference 

None. 

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Issued in Burlington, Massachusetts, on February 10, 2015 . 

Ann C. Mollica, 

Acting Directorate Manager, Engine & Propeller Directorate, 

Aircraft Certification Service. 

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