### June 26, 2015 CFM56/GAU_004_15

Subject: Subject: CFM International S.A. co mments for FAA NPRM - Docket No. AA2015-0277 

### ; Directorate Identifier 2015–N E–05–AD, dated May 1, 2015. Airworthiness Directives; CFM International S.A. Turbofan Engines.



### To whom it may concern,

CFM has reviewed the subject NPRM. Pl ease find the related comments attached.

Thanks and Best Regards,

Gregory Uhler ODA RCE, EASA CVE GE Aviation Airworthiness and Certification

T +1 513 552 3438 M +1 513 275 8861 gregory.uhler@ge.com

### CFM Comments: Docket No. FAA- 2015-0277; Directorate Identifier
2015–NE–05–AD

In “Summary” Section : Current: 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) insp ection of the affected gearshafts until removal.
To : This proposed AD was prompted by reports of one uncommanded in-flight shutdown (IFSD) on CFM CFM56–7B engines following rupture of the 73-tooth gearshaft located in the engine accessory gearbox (AGB). This proposed AD would require AGB/TGB magnetic chip detector (MCD) inspection of the affected gearshafts until removal.
Reason : Clarification that there was only one un-commanded IFSD. Clarification as to which MCD to inspect.



### In “Discussion” Section : Current : We have received reports of uncommanded IFSDs on CFM CFM56–7B engines following rupture of the 73-tooth gearshaft located in the engine AGB.
To : We have received reports of one uncommanded IFSD on CFM CFM56–7B engines following rupture of the 73- tooth gearshaft located in the engine AGB.
Reason : Clarification that there was only one un-commanded IFSD.

Current: The proposed AD requires enhanced MCD inspection until removal of the gearshaft.
To : The proposed AD requires enhanced AGB/TGB MCD inspection until removal of the gearshaft.
Reason : Clarification as to which MCD to inspect.



### In “Relevant Service Informati on Under 1 CFR Part 51” Section

Current : The SBs describe procedures for removal of affected 73- tooth and 41-tooth gearshafts.
To : The SBs list the affected gearshaft se rial numbers and describe procedures for removal of affected 73- tooth and 41-tooth gearshafts.
Reason : Expand definition of SB contents.



### In “Proposed AD Requirements” Section

Current : This proposed AD would require an MCD inspection within 250 FHs since last inspection or within 25 FHs after the effective date of this AD, whichever comes later.
To: After the effective date of this AD, the proposed AD would require an AGB/TGB MCD inspection within 250 FHs since last inspection or within 25 FHs, or before 300 0 FHs since first installation for 73 tooth or before 6000
FHs since first installation for 41 tooth whichever comes later.
Reason : Conform AD requirements to SB requirements regarding inspection times.



### In “Differences Between This Proposed AD and the Service Information” Section

Current : CFM SB CFM56–7B S/B 72–0964, Revision 1, dated December 15, 2014, 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. To: CFM SB CFM56–7B S/B 72–09 64, Revision 1 (or later revision), dated December 15, 2014, 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.
Reason: Include provision for later revisions of SB.

### In “PART 39—AIRWORTHINESS DIRECTIVES” Section (c) Applicablity

Current : ... CFM Service Bulletin (SB) CFM56–7B S/B 72–0964, Revision 1, dated December 15, 2014.
To: ... CFM Service Bulletin (SB) CFM56–7B S/B 72–0964, Revision 1 (or later revision), dated December 15,
2014.
Reason: Include provision for later revisions of SB.



### (d) Unsafe Condition

Current: 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.
To: This AD was prompted by reports of one uncommanded in-flight shutdown on CFM CFM56–7B engines following rupture of the 73-tooth gearshaft located in the engine AGB.
Reason: Clarification that there was only one un-commanded IFSD.



### (e) Compliance

Current: For affected 73-tooth gearshafts, pe rform an MCD inspection within 250 flight hours (FHs) since last inspection, within 25 FHs from the effective date of th is AD, or when the gearshaft accumulates 3,000 FHs since new, whichever comes later.
To: For affected 73-tooth gearshafts, perform an AGB/TGB MCD inspection w ithin 250 flight hours (FHs) since last inspection, within 25 FHs from the effective date of this AD, or when the ge arshaft accumulates 3,000 FHs since new, whichever comes later.
Reason: Clarification as to which MCD to inspect.



### (e) Compliance

Current: For affected 41-tooth gearshafts, pe rform an MCD inspection within 250 FHs since last inspection, within
25 FHs from the effective date of th is AD, or when the gearshaft accumul ates 6,000 FHs since new, whichever
comes later.
To: For affected 41-tooth gearshafts, pe rform an AGB/TGB MCD in spection within 250 FHs since last inspection, within 25 FHs from the effective date of this AD, or when the gearshaft accumu lates 6,000 FHs since new,
whichever comes later.
Reason : Clarification as to which MCD to inspect.



### (e) Compliance

Current : If any magnetic particles, including fuzz, are seen, determ ine with particles lab anal ysis if the particles are 73-tooth or 41-tooth gearshaft material.
To: If any magnetic particles, including fuzz, are seen, determ ine with laboratory analysis if the particles are 73- tooth or 41-tooth gearshaft material.
Reason : Conform AD requirements to SB requirements.



### (e) Compliance

Current : (i) For affected 73-tooth gearshafts, perform 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-t ooth 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 particle s lab analysis if the particles are 73- tooth or 41-tooth gearshaft material.
To: (i) For affected 73-tooth gearshafts, perform an AGB/TGB MCD inspection and laboratory analysis within every 500 FHs since the last MCD inspection until affected gearshaft is removed.(ii) For affected 41-t ooth gearshafts, perform an AG B/TGB MCD inspection and laboratory analysis within every 500 FHs since the last MCD inspection until affected gearshaft is removed. (iii) If any magnetic particles, includi ng fuzz, are seen, determine with labora tory analysis if the particles are 73- tooth or 41-tooth gearshaft material.
Reason : Conform AD requirements to SB requirements and clarify which MCD is to be inspected.

Additional Comment applicable to FAA NPRM and EASA PAD: If the Agencies include the CFM56-3 series engines in this proposed AD, CFM suggests that the affected part serial numbers be listed in the AD instead of the referencing the SBs, as CFM56-3 operators may not have access to the
CFM56-7B Service Bulletins..
Reason : Provide Agencies with additional information regarding the CFM56-3.