DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA-2015-0277; Directorate Identifier 2015-NE-05-AD] 

RIN 2120-AA64 

Airworthiness Directives; CFM International S.A. Turbofan Engines 

AGENCY: Federal Aviation Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking (NPRM). 

[4910-13-P] 

SUMMARY: We propose to adopt a new airworthiness directive (AD) for certain CFM 

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

prompted by reports of uncommanded in-flight shutdowns (IFSDs) on CFM CFM56-7B 

engines following rupture of the 73-tooth gearshaft located in the engine accessory 

gearbox (AGB). This proposed AD would require magnetic chip detector (MCD) 

inspection of the affected gearshafts until removal. We are proposing this AD to prevent 

fai lure of certain engine AGB gearshafts, which could lead to fai lure of one or more 

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

DATES: We must receive comments on this proposed AD by [INSERT DATE 60 

DAYS AFTER DATE OF PUBLICATION TN THE Federal Register]. 

ADDRESSES: You may send comments, using the procedures found in 14 CFR 11.43 

and 11.45, by any of the following methods: 

• Federal eRulemaking Portal: Go to http://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: Deliver to Mail address above between 9 a.m. and 5 p.m., 

Monday through Friday, except Federal holidays. 

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

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

phone: 877-432-3272; fax: 877-432-3329; email: aviation.tleetsupport@ge.com. You 

may view tills 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 8-7 125. 

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. FAA-2015-0277; 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 rebrulatory evaluation, any 

comments received, and other information. The street address for the Docket Office 

(phone: 800-647-5527) is in the ADDRESSES section. Comments wi ll be available in the 

AD docket shortly after receipt. 

FOR FURTHER INFORMATION CONTACT: Kyle Gustafson, Aerospace Engineer, 

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

Executive Park, Burlington, MA 01803; phone: 78 1-238-7183; fax: 78 1-238-7199; email: 

kyle.gustafson@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

We invite you to send any written relevant data, views, or arguments about th is 

proposal. Send your comments to an address listed under the ADDRESSES section. 

Include "Docket No. FAA-2015-0277; Directorate Identifier 2015-NE-05-AD" at the 

beginning of your comments. We specifically invite comments on the overall regulatory, 

2 
economic, environmental, and energy aspects of this proposed AD. We will consider a ll 

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 

http://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 ofuncommanded IFSDs on CFM CFM56-7B engines 

following rupture of the 73-tooth gearshaft located in the engine AGB. CFM has 

identif-ied an affected population of 73-tooth gearshafts that show premature wear on the 

teeth due to inadequate shot peening. In the process of its investigation, CFM identified 

an additional population of 41-tooth gearshafts that is subject to the same premature 

wear. The affected population of 73-tooth and 41-tooth geat·shafts exhibit a surface finish 

that leads to loss in oil film effectiveness, causing micro-pitting which eventually leads to 

material separating from the gearshaft and its eventual failure. 

The proposed AD requires enhanced MCD inspection until removal of the 

gearshaft. This enhanced inspection requires that any material, including fuzz, be sent to 

the particles lab for analysis to determine the source of the material. We are allowing 

affected engines to continue to operate for 75 flight hours (FHs) after the MCD 

inspection to provide sufficient time to determine the source of the materi al and to 

remove the affected gearshaft if the particles lab analysis finds that the source of the 

material is from an affected 73-tooth or 41-tooth gearshaft. The enhanced MCD 

inspection and particles lab analysis is repeated every 500 FHs after the initial MCD 

inspection until the affected gearshaft is removed from service. This condition, if not 

3 
corrected, could result in failure of certain engine AGB gearshafts, which could lead to 

fa ilure of one or more engines, loss of thrust control, and damage to the airplane. 

Relevant Service Information 

We reviewed CFM Service Bulletin (SBs) CFM56-7B SIB 72-0964, Revision I, 

dated December 15, 2014, and CFM56-7B SIB 72-0965, dated December 16, 2014. The 

SBs describe procedures for removal of affected 73-tooth and 41 -tooth gearshafts. This 

service information is reasonably available; see ADDRESSES for ways to access this 

service information. 

FAA's Determination 

We are proposing this AD because we evaluated all the relevant information and 

determined the unsafe condition descri bed previously is likely to exist or develop in other 

products of the same type design. 

Proposed AD Requirements 

This proposed AD would require an MCD inspection within 250 FHs since last 

inspection or within 25 FHs after the effecti ve date of this AD, whichever comes later. 

The proposed AD would also require that the MCD inspection be repeated every 500 FHs 

after the initial MCD inspection until removal of the affected gearshaft. The proposed AD 

would also require as terminating action that the affected gearshafts be removed. 

Differences Between this Proposed AD and the Service Information 

This proposed AD would require an MCD inspection 250 FHs since last 

inspection or withi n 25 FHs after the effective date of this AD, whichever comes later. 

CFM SB CFM56-7B SIB 72-0964, Revision I, dated December 15, 20 14, recommends 

performing a MCD inspection 250 FHs since last inspection or as soon as possible if the 

inspection was done more than 250 FHs ago. 

In this proposed AD, we are not requiring that operators send the particles to 

CFM for ana lysis. We are, however, requiring that operators determine if the particles are 

4 
73-tooth gearshaft or 41-tooth gearsha ft material. CFM56-7B S/B 72-0964 recommends 

that if any magnetic particles, including fuzz are seen, operators send the inspection 

results and lab analysis to CFM for disposition. 

Costs of Compliance 

We estimate that this proposed AD would affect about 67 engines installed on 

airplanes ofU.S. registry. We also estimate that it would take about 1 hour per engine to 

do the inspection and 8 hours per engine to replace each affected gearshaft. We estimate 

thirty-six 73-tooth gearshafts and forty 4 1-tooth gearshafts will need replacement at a 

cost of $12,480 and $7,680 per part, respectively. The average labor rate is $85 per hour. 

Based on these fi gures, we estimate the cost of the proposed AD on U.S. operators to be 

$8 13,855. 

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 authori ty ofthe 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 Vll , 

Part A, Subpart III, Section 44 70 I : "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 determined that this proposed AD would not have federalism implications 

under Executive Order 13132. This proposed AD would not have a substantial direct 

5 
effect on the States, on the relationship between the national Government and the States, 

or on the distribution of power and responsi bi I i ties among the various levels of 

government. 

For the reasons discussed above, I certify this 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), 

(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. 

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, 4470 1. 

§ 39.13 [Amended] 

2. The FAA amends§ 39.13 by adding the following new airworthiness directive 

(AD): 

CFM International S.A.: Docket No. F AA-20 15-0277; Directorate lclenti fier 20 15-NE05-AD. 

6 
(a) Comments Due Date 

We must receive comments by [TNSERT DATE 60 DAYS AFTER DATE OF 

PUBLICATION JN THE Federal Register]. 

(b) Affected ADs 

None. 

(c) Applicability 

This AD applies to CFM International S.A. (CFM) CFM56-7B engines with 

accessory gearboxes (AGBs), with 73-tooth gearshafts or 41-tooth gearshafts, identified 

in Appendix A and Appendix B of CFM Service Bulletin (SB) CFM56-7B S/B 72-0964, 

Revision 1, dated December 15,2014. 

(d) Unsafe Condition 

This AD was prompted by reports of uncommanded in-flight shutdowns on CFM 

CFM56-7B engines following rupture of the 73-tooth gearshaft located in the engine 

AGB. We are issuing this AD to prevent failure of certain AGB gearshafts, which could 

lead to failure of one or more engines, loss of thrust control, and damage to the airplane. 

(e) Compliance 

Comply with this AD within the compliance times specified, unless already done. 

(1) Initial Magnetic Chip Detector (MCD) Inspection and Analysis 

(i) For affected 73-tooth gearshafts, perform an MCD inspection within 250 flight 

hours (FHs) since last inspection, within 25 FHs from the effecti ve date of this AD, or 

when the gearshaft accumulates 3,000 FHs since new, whichever comes later. 

(ii) For affected 41-tooth gearshafts, perform an MCD inspection within 250 FHs 

since last inspection, within 25 FHs fi·om the effective date of this AD, or when the 

geru·shaft accumulates 6,000 FHs since new, whichever comes later. 

(iii) If any magnetic particles, including fuzz, are seen, determine with particles 

lab analysis if the particles are 73-tooth or 41-tooth gearshaft material. 

7 
(iii) If any magnetic particles, including fuzz, are seen, determine with particles 

lab analysis if the particles are 73-tooth or 41-tooth gearshaft material. 

(iv) If the particles are 73-tooth or 41 -tooth gem·shaft material, remove the 

affected gearshaft(s) within 75 FHs since the MCD inspection. 

(2) Repetitive MCD Inspection and Analysis 

(i) For affected 73-tooth gearshafts, perfom1 an MCD inspection and particles lab 

analysis within every 500 FHs since the last MCD inspection until affected gearshaft is 

removed. 

(ii) For affected 41-tooth gearshafts, perform an MCD inspection and particles lab 

analysis within every 500 FHs since the last MCD inspection until affected gearshaft is 

removed. 

(iii) If any magnetic particles, including fuzz, are seen, determine with particles 

lab analysis if the particles are 73-tooth or 41-tooth gearshaft material. 

(iv) If the particles are 73-tooth or 41-tooth gearshaft material, remove the 

affected gearshaft(s) within 75 FI-ls since the MCD inspection. 

(f) Mandatory Terminating Action 

(1) Remove the affected 73-tooth gearshaft prior to the gearshaft accumulating 

6,000 FI-ls since new or within 50 FHs after the effective date of this AD, whichever 

comes later. 

(2) Remove the affected 41-tooth gearshaft prior to the gearshaft accumulating 

9,000 FI-ls since new or within 50 fHs after the effective date of this AD, whichever 

comes later. 

(g) Installation Prohibition 

After the effective date of this AD, do not install an affected gearshaft into an 

AGB. 

8 
(h) Alternative Methods of Compliance (AMOCs) 

The Manager, Engine Certification Office, FAA, may approve AMOCs for 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. 

(i) Related Information 

(I) 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 0 1803; phone: 781-238-7 183; fax: 

781-23 8-7199; emai I: kyle.gustafson@faa.gov. 

(2) CFM SBs CFM56-7B SIB 72-0964, Revision 1, dated December 15,2014, 

and CFM56-7B SIB 72-0965, dated December 16, 2014, which are not incorporated by 

reference in this proposed AD, can be obtained from GE using the contact information in 

paragraph (i)(3) of this proposed AD. 

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

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

phone: 877-432-3272; fax: 877-432-3329; email: aviation.fleetsupport@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 ofthis materi al at the FAA, call 78 1-238-7125. 

Issued in Burlington, Massachusetts, on April 17, 2015. 

~~ Acting Manager , Engine & Propeller Directorate, 

Aircraft Certification Service. 

9