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LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D ENGINE -
GENERAL (72 - 00 -
00) - NON -
SYNCHRONOUS VIBRA TION MONIT ORING
RECOMMENDA TIONS FOR
ENGINES WITH NO.
BEARING SPRING FINGER
HOUSING FROM “GCJ”
SUPPLIER
SERVICE
BULLETIN T able of contents
1.
REVISION
INFORMA TION .
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2.
SUMMAR Y .
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2 A.
Reason .
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3.
PLANNING
INFORMA TION .
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2 A.
Applicability .
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2 B.
Concurrent requirements .
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3 C.
Reason .
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3 D.
Description .
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3 E.
Compliance .
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3 F .
Approval .
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4 G.
Manpower .
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4 H.
W eight and balance .
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4 I.
Electrical load data .
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4 J.
Software accomplishment summary .
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4 K.
Referenced documentation .
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4 L.
Documentation af fected .
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4 M.
Industry support information .
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4 N.
Interchangeability .
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4.
MA TERIAL
INFORMA TION .
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5.
ACCOMPLISHMENT
INSTRUCTIONS .
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5 A.Alternative Procedure A vailable - NSV Monitoring with Fleeting Reports .
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5 B.Alternative Procedure - NSV Monitoring with ACMS T akeof f Reports .
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7 C.Housing Removal and Replacement .
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6.
ADDITIONAL
INFORMA TION .
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12 A.
Additional information .
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12 List of tables T able:
References .
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2 T able 1:
LEAP - 1A Engines with Af fected No.
3 Bearing Spring Finger Housing P/N 2629M62G01 .
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10 T able 2:
CFM Contact Information .
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13 LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D Page 1/ 14 Issue 001 - 00 - 2025 - 04 - 30 © CFM
PROPRIET AR Y
INFORMA TION:
Subject to the restrictions on the media.
LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D List of figures Figure 1:
No.
3 Bearing Spring Finger Housing Location .
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1 1 CFM
PROPRIET AR Y
INFORMA TION The information contained in this document is CFM proprietary information and is disclosed in confidence.
It is the property of CFM and shall not be used, disclosed to others or reproduced without the express written consent of CFM, including, but without limitation, it is not to be used in the creation, manufacture, development, or derivation of any repairs, modifications, spare parts, design, or configuration changes or to obtain F AA or any other government or regulatory approval to do so.
If consent is given for reproduction in whole or in part, this notice and the notice set forth on each page of this document shall appear in any such reproduction in whole or in part.
The information contained in this document may also be controlled by U.S.
export control laws.
Unauthorized export or re - export is prohibited.
References T able:
References T echnical Publication LEAP - 1A - 71 - 00 - 0013 - 01A - 930A - D LEAP - 1A - 72 - 00 - 0536 - 01A - 930A - D LEAP - 1A - 72 - 61 - 00 - 01A - 530A - C LEAP - 1A - 72 - 61 - 00 - 01A - 710A - C Management information Manufacturer recommendation:
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Recommended T ask type:
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Inspection Original issue date:
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2025 - 04 - 30
1.
REVISION
INFORMA TION Not Applicable.
2.
SUMMAR Y A.
Reason This Service Bulletin provides recommendations for monitoring non - synchronous vibration (NSV) during engine operation, using engine - generated data and snapshot reports to reduce significant events.
3.
PLANNING
INFORMA TION A.
Applicability LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D Page 2/ 14 Issue 001 - 00 - 2025 - 04 - 30 © CFM
PROPRIET AR Y
INFORMA TION:
Subject to the restrictions on the media.
LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D This Service Bulletin is applicable to:
• Engine type:
LEAP - 1A
• Engine model(s):
LEAP - 1A23,LEAP - 1A24,LEAP - 1A24E1,LEAP - 1A26,LEAP - 1A26CJ,LEAP - 1A26E1,LEAP - 1A29,LEAP - 1A29CJ,LEAP - 1A30,LEAP - 1A32,LEAP - 1A33,LEAP - 1A33B2,LEAP - 1A35A This Service Bulletin is applicable to all LEAP - 1A engines which have installed any of the No.
3 ball and roller bearing housings (No.
3 bearing spring finger housings) P/N 2629M62G01 with a serial number (S/N) listed in T able 1 of paragraph
5.,
ACCOMPLISHMENT INSTRUCTIONS.
B.
Concurrent requirements None.
C.
Reason
(1) Objective:
This Service Bulletin provides recommendations for monitoring NSV during engine operation, using engine - generated data and snapshot reports to reduce significant events.
(2) Condition:
LEAP - 1A engines with elevated NSV indications may be at risk for premature hardware deterioration, engine stalls, or false alerting.
(3) Cause:
Elevated NSV indications can occur because of multiple conditions, including but not limited to No.
3 bearing spring finger housing (SIN:
052A6) wear , oil flow interruption, low oil temperatures, erroneous accelerometer sensor feedback, or data corruption issues.
(4) Inspection:
CFM recommends LEAP - 1A engines be monitored for elevated NSV indications and removed from service if NSV indications exceed thresholds provided in this Service Bulletin.
(5) Substantiation:
Substantiation is by analysis, test, and fleet experience.
D.
Description This Service Bulletin provides recommendations for monitoring NSV during engine operation, using engine - generated data and snapshot reports to reduce significant events.
E.
Compliance Category 2 For LEAP - 1A engines with a No.
3 bearing spring finger housing listed in T able 1 of paragraph
5.,
ACCOMPLISHMENT
INSTRUCTIONS, CFM recommends that you do this Service Bulletin as soon as possible without ef fect on revenue services but before or at every 50 cycle interval of engine operation.
At the issuance of this Service Bulletin, do the initial NSV evaluation within 50 flight cycles after the issuance of this Service Bulletin.
Impact B This recommendation is to address a condition that may result in an Increased Rate of In - Flight Shutdowns (IFSD), T ake - Of f Aborts (T OA), Air T urn Backs (A TB) or Diversions (DIV).
NOTE:
Some steps in paragraph
5.,
ACCOMPLISHMENT
INSTRUCTIONS are identified as required for compliance (RC).
If this Service Bulletin is mandated by an airworthiness directive (AD), the steps identified as RC must be done to comply with the AD.
Steps not identified with RC are recommended and may be LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D Page 3/ 14 Issue 001 - 00 - 2025 - 04 - 30 © CFM
PROPRIET AR Y
INFORMA TION:
Subject to the restrictions on the media.
LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D deviated from, done as a part of other actions, or done with accepted methods different from those given in this Service Bulletin if the RC steps can be done and the airplane returned to a serviceable condition.
NOTE:
This Service Bulletin can be done on wing.
This Service Bulletin is of fered to improve the reliability or performance of your CFM product, or to help prevent the occurrence of the event or condition described in this Service Bulletin.
If the operator elects not to participate in the bulletin, that decision will be taken into consideration by CFM in evaluating future product performance issues that may arise in the operator ’ s fleet.
F .
Approval The technical content of this Service Bulletin is approved by the F AA and under the Authority of DOA No.
EASA.21J.086.
G.
Manpower No additional man - hours are required to comply with this Service Bulletin.
H.
W eight and balance W eight and balance are not changed.
I.
Electrical load data Not Applicable.
J.
Software accomplishment summary Not Applicable.
K.
Referenced documentation Airbus A318/A319/A320/A321 Aircraft Maintenance Manual (AMM) CFM LEAP - 1A Engine Illustrated Parts Catalog (EIPC), CFM - TP - 610 EIPC.20 CFM LEAP - 1A Engine Shop Manual (ESM), CFM - TP - 610 SM.20 CFM Service Bulletin LEAP - 1A 71 - 0013, POWER PLANT -
GENERAL (71 - 00 -
00) -
INSTRUCTIONS FOR
PROVIDING
ACMS/EEC
SNAPSHOT REPOR TS T O CFM WHEN DA T A
TRANSMISSION IS
INTERRUPTED CFM Service Bulletin LEAP - 1A 72 - 0536, ENGINE -
GENERAL (72 - 00 -
00) -
RECOMMENDA TIONS FOR
ENGINES WITH
POTENTIAL NO.
BEARING SPRING FINGER
HOUSING WEAR L.
Documentation affected None.
M.
Industry support information None.
N.
Interchangeability Not Applicable.
4.
MA TERIAL
INFORMA TION List of material sets Not Applicable.
LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D Page 4/ 14 Issue 001 - 00 - 2025 - 04 - 30 © CFM
PROPRIET AR Y
INFORMA TION:
Subject to the restrictions on the media.
LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D List of support equipment Not Applicable.
List of supplies Not Applicable.
List of spares Not Applicable.
List of removed spares Not Applicable.
5.
ACCOMPLISHMENT
INSTRUCTIONS A.
Alternative Procedure A vailable - NSV Monitoring with Fleeting Reports
(1) RC - Evaluation of Post - Flight Data A vailability and A vailable NSV Data.
NOTE:
If step
5.B.(1) is completed, then step
5.A.(1) is not necessary for compliance.
(a) At or before each 50 - cycle interval, CFM recommends to evaluate your post - flight summary data availability and available NSV fleeting reports as follows:
NOTE:
Post - flight data availability can be evaluated on myCFM Portal (https://mycfmportal.com), CFM Fleet Monitor (https://fleetmonitor .mycfmportal.com), Fleet Monitor X (https://my .geaviation.
com/fmx), or similar online tools.
1 If you have 100 cycles or higher of post - flight data within the past 125 cycles, continue with step
5.A.(1)(b).
2 Alternative Procedure A vailable.
If you have 0 to 99 cycles of post - flight data within the past 125 cycles, get additional post - flight summary (PFS) data as specified in step
5.A.(2) within the next 50 cycles to restore your PFS data to 100 cycles or higher and do as follows:
a If data coverage requirement is met, continue with step
5.A.(1)(b).
b If data coverage requirement is not met, remove the engine within 50 cycles.
3 Alternative Procedure.
Examine your NSV with the aircraft condition monitoring system (ACMS) method as specified in step
5.B.
4 Alternative Procedure.
If suf ficient data coverage from step
5.A.
or step
5.B.
cannot be met and calculations were not made as specified in step
5.A.
or step
5.B., remove the engine within 50 cycles.
NOTE:
Increased data coverage can improve the effectiveness of this NSV monitoring.
(b) After data availability is 100 cycles or higher of post - flight data within the past 125 cycles, compare available NSV fleeting reports as specified in step
5.A.(3) and step
5.A.(4).
(2) Recommendations for Obtaining Additional Post - Flight Data (if necessary).
(a) Alternative Procedure A vailable.
Download electronic engine control (EEC) snapshot reports and send to CFM for NSV monitoring.
Refer to the LEAP - 1A S/B 71 - 0013 ( Refer to SB:
LEAP - 1A - 71 - 00 - 0013 - 01A - 930A - D ) and do as follows:
1 Send all downloaded data to CFM through standard processes.
LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D Page 5/ 14 Issue 001 - 00 - 2025 - 04 - 30 © CFM
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LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D
(b) Alternative Procedure.
If EEC snapshots are already available from the EEC or are available in other customer location, then send all data to CFM through standard processes.
(3) RC - NSV T rend Monitoring with CFM Diagnostics.
NOTE:
If step
5.B.(3) is completed, then step
5.A.(3) is not necessary for compliance.
NOTE:
CFM Diagnostics uses alert technology on a flight - by - flight basis dependent on EEC post - flight summary and fleeting reports snapshot data given to CFM.
If the conditions are present to generate an alert based on the guidance specified in this Service Bulletin, the data will be evaluated and a customer notification report (CNR) will be issued to the operator .
(a) The use of CFM diagnostics on myCFM Portal (https://mycfmportal.com) is contingent upon the regular submittal of PFS and vibration fleeting event (FL T) reports to CFM.
NOTE:
The parameters available in CFM Fleet Monitor (https://fleetmonitor .mycfmportal.com) trends can also be accessed via myCFM Portal Plotting widget.
myCFM Portal, CFM Fleet Monitor , or equivalent CFM web - based tools can be used for engine health trend monitoring.
The myCFM Portal Data Query widget can also be used to set - up an automated query for the parameters necessary for monitoring engine condition.
NOTE:
The parameter "NSV TCF Max V ibe Fleeting" is also referred to as NSV Fleeting Reports in this Service Bulletin.
(b) Do the steps that follow to find the "NSV TCF Max V ibe Fleeting" values:
1 Access to CFM Fleet Monitor (https://fleetmonitor .mycfmportal.com) and enter the engine serial number in the search window .
2 Select T rends tab and open the "LEAP NSV" plotset.
3 A custom trend plot can be created with the selections that follow:
a Select "Create new" or "Create a new trend".
b Select "All" or "Engine" for the parameters category .
c Select "NSV TCF Max V ibe Fleeting" from the search bar .
d Select Update.
NOTE:
"NSV TCF Max V ibe Fleeting" can be displayed as "NSV TCF Max V ibe Fleeting
FLEETING EVENT Raw" in the CFM Diagnostics tools.
NOTE:
FL T reports can be generated for various vibration parameters.
FL T reports are only generated because of NSV levels if the NSV level is more than or equal to
1.1 Gs in magnitude.
When "NSV TCF Max V ibe Fleeting" is at a value of 0 G, it is not actual measurement of NSV and is not to be used for NSV monitoring.
NOTE:
The "LEAP NSV" plotset also includes other parameters from snapshot reports, which can be able to help to find out whether the NSV indications are because of low oil temperature or TCF accelerometer feedback issues.
NOTE:
It can be necessary to modify the "Date Range" drop down on the trends tab in order to update the date range for this data.
(c) Compare your available NSV Fleeting reports to the limits in step
5.A.(4).
LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D Page 6/ 14 Issue 001 - 00 - 2025 - 04 - 30 © CFM
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LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D
(4) NSV Monitoring Recommendations.
(a) CFM recommends to use the monitoring thresholds that follow and do the maintenance recommendations when NSV indications are present because of conditions which can progress to an NSV stall:
1 RC - If there are three or more NSV fleeting reports, more than or equal to
1.1 Gs in magnitude in the past 50 cycles, CFM recommends engine removal within 25 cycles from the flight when this threshold is exceeded and follow the requirements in step
5.A.(4)(a)4.
NOTE:
If step
5.B.(4)(a)1 is completed, then step
5.A.(4)(a)1 is not necessary for compliance.
2 RC - If there is one or more NSV fleeting reports, more than or equal to
2.0 Gs in magnitude in the past 50 cycles, CFM recommends engine removal within 5 cycles from the flight when this threshold is exceeded and follow the requirements in step
5.A.(4)(a)4.
NOTE:
If step
5.B.(4)(a)1 is completed, then step
5.A.(4)(a)2 is not necessary for compliance.
3 If the threshold in step
5.A.(4)(a)1 or step
5.A.(4)(a)2 is exceeded, before engine removal CFM recommends engine de - rate during takeof f whenever possible in order to reduce the potential for stall.
4 RC - When the engine is removed as specified in step
5.A.(4)(a)1 or step
5.A.(4)(a)2 and sent to a maintenance facility , the actions that follow are necessary:
NOTE:
If step
5.B.(4)(a)3 is completed, then step
5.A.(4)(a)4 is not necessary for compliance.
a Remove and scrap the No.
3 bearing spring finger housing (1, Figure 1 ) (SIN:
052A6).
Refer to LEAP - 1A S/B 72 - 0536 ( Refer to SB:
LEAP - 1A - 72 - 00 - 0536 - 01A - 930A - D ).
b Do an inspection and disposition of stage 2 high pressure turbine (HPT) nozzle assembly (SIN:
17300) and the HPT stator stationary seal (SIN:
925A3).
Refer to LEAP - 1A S/B 72 - 0536 ( Refer to SB:
LEAP - 1A - 72 - 00 - 0536 - 01A - 930A - D ).
NOTE:
Some NSV indications as described in paragraph
6.,
ADDITIONAL
INFORMA TION can alert the NSV trending or fleeting reports, but could not indicate that a condition is present that could progress to a NSV stall.
Before engine removal, CEOD and other snapshot data from flights with elevated NSV levels can be reviewed to find out the potential cause of the NSV indications.
Refer to step
6.A.(3) to contact CFM.
B.
Alternative Procedure - NSV Monitoring with ACMS T akeoff Reports
(1) RC - Evaluation of ACMS reports A vailability and Calculated NSV Data NOTE:
If step
5.A.(1) is completed, then step
5.B.(1) is not necessary for compliance.
NOTE:
Parameter from ACMS takeoff named VB is the measured value of the overall engine vibrations that can be used for data availability .
NOTE:
If CFM Diagnostics is not used for NSV monitoring as specified in step
5.A., the operator can use their available ACMS takeoff data for monitoring with the steps mentioned below .
(a) At or before each 50 cycles interval, CFM recommends that you do a check of the parameter VB with the evaluation of your available ACMS takeof f data as follows:
1 If you have 100 cycles or higher of parameter VB within the past 125 cycles, continue with step
5.B.(1)(b).
LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D Page 7/ 14 Issue 001 - 00 - 2025 - 04 - 30 © CFM
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INFORMA TION:
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LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D 2 Alternative Procedure A vailable.
If you have 0 to 99 cycles of parameter VB the past 125 cycles, get additional ACMS takeof f as specified in step
5.B.(2) within the next 50 cycles to restore your ACMS data to 100 cycles or higher and do as follows:
a If data coverage requirement is met, continue with step
5.B.(1)(b).
b If data coverage requirement is not met, remove the engine within 50 cycles.
3 Alternative Procedure.
Examine your NSV monitoring with the NSV fleeting reports in step
5.A.
4 Alternative Procedure.
If suf ficient data coverage from step
5.A.
or step
5.B.
cannot be met and NSV evaluation were not made as specified in step
5.A.
or step
5.B., remove the engine within 50 cycles.
NOTE:
Increased data coverage can improve the effectiveness of this NSV monitoring.
(b) After data availability is 100 cycles or higher of parameter VB within the past 125 cycles, calculate your estimated NSV and apply NSV monitoring recommendations as specified in steps
5.B.(3) and step
5.B.(4).
(2) Recommendations for Obtaining Additional ACMS Data (if necessary).
(a) Download aircraft condition monitoring system (ACMS).
Refer to the LEAP - 1A S/B 71 - 0013 ( Refer to SB:
LEAP - 1A - 71 - 00 - 0013 - 01A - 930A - D ).
(3) RC - Calculating Estimated NSV with ACMS Data.
NOTE:
If step
5.A.(3) is completed, then step
5.B.(3) is not necessary for compliance.
(a) For all available ACMS data over the past 125 cycles, get the parameters that follow from ACMS takeof f reports and from the same flight to calculate the estimated NSV value known as "Estimated NSV (Gs)", as calculated in step
5.B.(3)(e).
NOTE:
Parameter values from ACMS takeoff reports must be used with appropriate decimal format.
Refer to the Airbus A318/A319/A320/A321 AMM, 31 - 37 - 73, AIDS - ENGINE REPOR TS, for number formatting of the parameters.
1 N1ACT = Selected N1 actual NOTE:
This parameter N1ACT is in percentage of measured fan speed and it needs to be converted in step
5.B.(3)(b) before it is used in step
5.B.(3)(c).
2 VB = TRF pick up Broadband vibration NOTE:
This parameter VBs units are in "ips" and it does not need to be converted to do the calculation in step
5.B.(3)(d).
3 VL = TRF pick up N1 track vibration NOTE:
This parameter VLs units are in "mils" and it needs to be converted in step
5.B.(3)(c) before the calculation in step
5.B.(3)(d).
4 VH = TRF pick up N2 track vibration NOTE:
This parameter VHs units are in "ips" and it does not need to be converted to do the calculation in step
5.B.(3)(d).
(b) Convert "N1ACT" to "N1ACT (rad/sec)" as follows:
NOTE:
The value N1ACT from step
5.B.(3)(a) is necessary for this conversion.
LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D Page 8/ 14 Issue 001 - 00 - 2025 - 04 - 30 © CFM
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LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D 1 N1ACT (rad/sec) = (N1ACT /
100) * 3856 (rpm) * ((2 *
3.14159) /
60) (rad/sec)
(c) Use the equation that follows to convert "VL" to "VL (ips)":
NOTE:
V alue VL from step
5.B.(3)(a) and converted value N1ACT (rad/sec) from step
5.B.(3)(b) are necessary for this conversion.
1 VL (ips) = (VL) * (N1ACT (rad/sec)) / 2000 (in / mils - DA)
(d) Use the equation that follows to calculate "Estimated NSV (ips)":
NOTE:
The value of VB from step
5.B.(3)(a), converted value VL (ips) from step
5.B.(3)(c), and value of VH from step
5.B.(3)(a) are necessary for this calculation.
1 Estimated NSV (ips) = sqrt (VB^2 - (VL (ips))^2 - VH^2)
(e) Use the equation that follows to calculate "Estimated NSV (Gs)":
NOTE:
Calculated value "Estimated NSV (ips)" from step
5.B.(3)(d) is necessary for this calculation.
1 Estimated NSV (Gs) = Estimated NSV (ips) *
1.79
(f) Compare all available calculated "Estimated NSV (Gs)" values over the past 125 cycles that were calculated in step
5.B.(3)(e) to the NSV limits in step
5.B.(4).
(4) NSV Monitoring Recommendations.
NOTE:
If step
5.A.(1) has adequate data coverage and does not require removal of the engine as specified in step
5.A.(3) and step
5.A.(4), then this step
5.B.(4) does not need engine removal even if limits are exceeded.
(a) CFM recommends to use the monitoring thresholds that follow and do the maintenance recommendations when NSV indications are because of conditions which can progress to an NSV stall:
1 RC - If there are three or more calculated "Estimated NSV (Gs)" values from step
5.B.(3)(e) more than or equal to
1.1 Gs in magnitude in the past 125 cycles, CFM recommends engine removal within 25 cycles from the flight when this threshold is exceeded and obey the requirements in step
5.B.(4)(a)3.
NOTE:
If step
5.A.(4)(a)1 or step
5.A.(4)(a)2 is completed, then step
5.B.(4)(a)1 is not necessary for compliance.
2 If the threshold in step
5.B.(4)(a)1 is exceeded, before engine removal CFM recommends engine de - rate during takeof f whenever possible in order to reduce the potential for stall.
3 RC - When the engine is removed as specified in step
5.B.(4)(a)1 and sent to a maintenance facility , the actions that follow are necessary:
NOTE:
If step
5.A.(4)(a)4 is completed, then step
5.B.(4)(a)3 is not necessary for compliance.
a Remove and scrap the No.
3 bearing spring finger housing (1, Figure 1 ) (SIN:
052A6).
Refer to LEAP - 1A S/B 72 - 0536 ( Refer to SB:
LEAP - 1A - 72 - 00 - 0536 - 01A - 930A - D ).
b Do an inspection and disposition of stage 2 HPT nozzle assembly (SIN:
17300) and the HPT stator stationary seal (SIN:
925A3).
Refer to LEAP - 1A S/B 72 - 0536 ( Refer to SB:
LEAP - 1A - 72 - 00 - 0536 - 01A - 930A - D ).
LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D Page 9/ 14 Issue 001 - 00 - 2025 - 04 - 30 © CFM
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INFORMA TION:
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LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D C.
Housing Removal and Replacement
(1) When any of the LEAP - 1A engines with a No.
3 bearing spring finger housing serial numbers (S/N) listed in T able 1 is removed from service and the scrapped No.
3 bearing spring finger housing (1, Figure 1 ) (SIN:
052A6) is replaced with a serviceable No.
3 bearing spring finger housing
(1) (SIN:
052A6) not listed in T able 1 , then this NSV monitoring as specified in step
5.A.
or step
5.B.
is not necessary .
Removal and installation instructions have not changed.
Refer to the LEAP - 1A ESM, 72 - 61 - 00,
DISASSEM- BLE
PROCEDURE ( Refer to:
LEAP - 1A - 72 - 61 - 00 - 01A - 530A - C ) and
ASSEMBLE
PROCEDURE ( Refer to:
LEAP - 1A - 72 - 61 - 00 - 01A - 710A - C ).
NOTE:
Manufacturing records show that the No.
3 bearing spring finger housing S/Ns listed in T able 1 of paragraph
5.,
ACCOMPLISHMENT
INSTRUCTIONS are installed on the ESNs listed.
ESNs are shown for reference only .
(2) Make sure to review your delivery and maintenance records to find the S/Ns of the No.
3 bearing spring finger housings (1, Figure 1 ) (SIN:
052A6) listed in T able 1 that are installed in your LEAP - 1A engines.
T able 1:
LEAP - 1A Engines with Af fected No.
3 Bearing Spring Finger Housing P/N 2629M62G01 LEAP - 1A ESN No.
3 Bearing Spring Finger Housing S/N LEAP - 1A ESN No.
3 Bearing Spring Finger Housing S/N 59A867 GCJ000HF 59A899 GCJ000H6 59A903 GCJ000H9 59B036 GCJ000H2 59B052 GCJ000H7 59B067 GCJ000LA 59B075 GCJ000HK 59B191 GCJ000E8 59B276 GCJ000HJ 59B302 GCJ000L7 59B306 GCJ000EA 59B328 GCJ000L9 59B353 GCJ000L3 59B382 GCJ000HA 59B389 GCJ000H4 59B407 GCJ000H3 59B419 GCJ000HC 59B433 GCJ000LH 59B447 GCJ000LL 59B455 GCJ000LC 59B457 GCJ000H8 59B490 GCJ000LE 59B51 1 GCJ000L1 59B521 GCJ000LK 59B820 GCJ000W5 59B871 GCJ000WJ LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D Page 10/ 14 Issue 001 - 00 - 2025 - 04 - 30 © CFM
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INFORMA TION:
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cfm The Power of Flight LEAP-1A-72-00-0562-01A-930A-D
INLET GEARBOX AND NO. 3 BEARING
ASSEMBLY (SIN: 03000) Л'WO VIEW A LEGEND:
1. NO. 3 BEARING SPRING FINGER HOUSING (SIN: 052A6) ICN-LEAP-1A-7200056 482-00001-A-001-01 No. 3 Bearing Spring Finger Housing Location Figure 1 LEAP-1A-72-00-0562-01A-930A-D Page 11/14 Issue 001-00 - 2025-04-30 © CFM PROPRIETARY INFORMATION: Subject to the restrictions on the media
LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D
6.
ADDITIONAL
INFORMA TION A.
Additional information
(1) NSV Monitoring Recommendations
(a) CFM recommends monitoring LEAP - 1A engines for elevated NSV with the PFS and FL T EEC generated snapshot reports.
1 The PFS report contains a measurement of the maximum NSV value that occurs within plus or minus 60 seconds of takeof
f.
There is no magnitude or persistence associated with the NSV trending report.
PFS reports are generated by the EEC after engine shutdown after a flight.
NOTE:
This NSV trending parameter is called "NSV TCF Max V ibe T rending" on CFM Diagnostics.
NOTE:
This NSV trending parameter is not currently used for engine removal recommendations but can be used to evaluate NSV signals.
2 The FL T report can be generated on - condition when the value of the NSV parameter is more than
1.1 Gs for over 2 seconds of persistence.
FL T reports are generated on - condition when any one of various vibration parameters are higher than a monitoring threshold.
A FL T report with an NSV parameter that shows "0" does not indicate the NSV level was
0.0 G at that flight, but typically means the FL T report was generated because of a non - NSV vibration parameter .
NOTE:
This NSV on - condition parameter is called "NSV TCF Max V ibe Fleeting" on CFM Diagnostics.
(2) Background Information for NSV Indication Causes and Effects
(a) Elevated NSV indications can occur because of the conditions that follow .
These conditions can occur independently or in combination.
Some sources of NSV can indicate the engine is at risk of premature hardware deterioration, engine stalls, and/or limited ability to accelerate the engine above idle.
1 No.
3 bearing spring finger housing (SIN:
052A6) wear .
2 No.
3 bearing damper oil flow interruption.
3 Low oil temperatures.
4 Erroneous accelerometer sensor feedback.
5 Data corruption issues.
(b) The No.
3 bearing damper system is a squeeze film damper design.
The oil film between the No.
3 roller (machining) bearing housing (damper housing) (SIN:
052A8) and the No.
3 bearing spring finger housing (SIN:
052A6) is squeezed during LEAP - 1A engine operation.
Resultant pressures exert reaction forces on the damper housing (SIN:
052A8), thereby reducing the high pressure rotor response to imbalance.
The No.
3 bearing spring finger housing (SIN:
052A6) can be susceptible to wear in the ring number 3 bearing piston (piston ring) (SIN:
052N2) grooves.
After some accumulated wear , the piston rings (SIN:
052N2) can be lodged between the No.
3 bearing spring finger housing (SIN:
052A6) and the damper housing (SIN:
052A8).
This can lead to a reduction in the damping of the squeeze film design and progress to NSV on the high pressure rotor at high thrust settings where torque is at high levels.
This NSV can cause the high pressure rotor to whirl as it rotates and potentially af fect high pressure compressor (HPC) tip clearances.
This can result in an HPC stall at elevated thrust settings.
1 No.
3 bearing spring finger housing (SIN:
052A6) wear typically generates fine particles that consist mostly of 15 - 5 PH material that are captured in the oil scavenge filter and result in elevated oil filter delta pressure LEAP - 1A - 72 - 00 - 0562 - 01A - 930A - D Page 12/ 14 Issue 001 - 00 - 2025 - 04 - 30 © CFM
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