# JASC 2421: AC Generator-Alternator

- Type: JASC system/component code (FAA)
- ATA chapter: 24 Electrical Power
- Title in the code table: AC GENERATOR-ALTERNATOR
- Service difficulty reports: 4,273
- FAA code table: https://www.faa.gov/sites/faa.gov/files/JASC_Code.pdf#page=20
- Page: https://openairdocs.org/jasc/2421

## What it covers

The engine driven component that generates alternating current (AC) for aircraft with AC electrical systems. Does not include AC alternators on light piston-engine power aircraft with direct current (DC) electrical systems. Does not include single units used for both engine starting and electric power generating. Typical parts are bearing, shaft, housing, and integrated drive generator (IDG) which contains both AC and DC generators.

## Service difficulty reports (4,273, newest 50)

- [SDR ABXA20261019472](https://openairdocs.org/sdr/ABXA20261019472), Oct 19, 2026: Boeing 76736N. GENERATOR. FAULTED. L GEN DRIVE DISC LIGHT FLICKERING ON PUSHBACK AFTER ENGINE STARTA/C RETURNED TO THE GATE (BTB) AND MTX GROUNDED A/C. MTX (N1013A)
- [SDR AALA202610195389](https://openairdocs.org/sdr/AALA202610195389), Oct 16, 2026: Boeing 737823. GENERATOR. INOPERATIVE. AIRCRAFT WAS GROUNDED: -- DECISION WAS MADE TO RETURN TO ORD. EMERGENCY DECLARED; AIRCRAFT LANDED OVERWEIGHT WITHOUT INC (N974AN)
- [SDR N3XR202610130001](https://openairdocs.org/sdr/N3XR202610130001), Oct 9, 2026: Cessna 172S. CONTROL UNIT. BURNED. THE ALTERNATOR CIRCUIT BREAKER POPPED AFTER A PREVIOUS RESET. THE ACU (ALTERNATOR CONTROL UNIT) P/N-AC2101, S/N-Y59830 F (N923ER)
- [SDR QREA202610140007](https://openairdocs.org/sdr/QREA202610140007), Oct 7, 2026: Cessna 525C. ALTERNATOR. OVERHEATED. RIGHT AC GENERATOR FAILED IN FLIGHT WHICH CAUSED RH WINDSHEILD HEAT FAIL. AIRCRAFT WAS ENROUTE TO TXKF OCEANING FLIGHT F (N5JM)
- [SDR AALA202609273893](https://openairdocs.org/sdr/AALA202609273893), Sep 26, 2026: Airbus A321231. IDG. FAILED. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO DFW DUE TO THE FLIGHT CREW REPORTING THAT  (N519UW)
- [SDR AALA202609254693](https://openairdocs.org/sdr/AALA202609254693), Sep 23, 2026: Boeing 7879. GENERATOR. DISCONNECTED. AIRCRAFT WAS NOT GROUNDED: LEC GEN DRIVE L1 ILLUM IN FLT. L1 GENERATOR WAS DISCONNECTED PER THE CHECKLIST. GENERATOR DIS (N824AN)
- [SDR CALA2026092419779](https://openairdocs.org/sdr/CALA2026092419779), Sep 23, 2026: Boeing 767322. IDG. FAULTED. LEFT ENG OIL PRESSURE DROPPED TO RED LEVEL. LT ENG SHUTDOWN. OIL PRESS REMAINED AT 58. OIL LIFTED BY 22QTS. LT ENG IDLE  (N674UA)
- [SDR FDEA202609191372](https://openairdocs.org/sdr/FDEA202609191372), Sep 19, 2026: Doug MD11F. GCU. FAILED. AC BUSS 3 OFF LEVEL 1. BUSS DID NOT FAIL UNTIL MULTIPLE ITEMS ON BUSS FAILED OVER A PERIOD OF ABOUT 7 MINUTES. FIRST OIL (N605FE)
- [SDR CALA2026092119569](https://openairdocs.org/sdr/CALA2026092119569), Sep 19, 2026: Boeing 767322. IDG. FAULTED. EICAS MSG: LT GEN DRIVE DISPLAYED. GEN DRIVE LIGHT ILLUM. FOLLOWED CHECKLIST TO DISCONNECT LT GENERATOR, REMOVED & REPLA (N674UA)
- [SDR DALA2026092105254](https://openairdocs.org/sdr/DALA2026092105254), Sep 17, 2026: Boeing 7379GPER. IDG. INOPERATIVE. ABORTED TAKEOFF AT 60KTS DUE TO A NR 1 GENERATOR SOURCE OFF LIGHT. DEFERRED NR 1 GENERATOR PER MEL 24-000-01. REPLACED E (N951DX)
- [SDR CALA2026091819535](https://openairdocs.org/sdr/CALA2026091819535), Sep 16, 2026: Boeing 7879. GENERATOR. FAULTED. R2 GENERATOR FAILED. RESET IAW CHECKLIST, NOT SUCCESSFUL, FOUND MAINT MSG 24-16074 LATCHED. REMOVED NR 2 ENG R2 VFSG IAW (N24976)
- [SDR YENA2026091400798](https://openairdocs.org/sdr/YENA2026091400798), Sep 13, 2026: Airbus A321271NX. GENERATOR. MALFUNCTIONED. FLT 842, DUB-JFK. (ETOPS) AC GEN CLASS 2 MX MSG ( CLASS II MAINTENANCE MESSAGES DISPLAYED ON ECAM STATUS PAGE OF ECAM SY (N2142J)
- [SDR DALA2026091505142](https://openairdocs.org/sdr/DALA2026091505142), Sep 10, 2026: Airbus A321271NX. GPU. FAULTED. ATB - DUE TO ELEC GEN 1 FAULT. CORRECTIVE ACTION: DEFERRED NBR 1 ENGINE IDG DISCONNECT PROCEDURE PER A321 AMM 24-21-00 A (N515DE)
- [SDR I5PA2026090888802](https://openairdocs.org/sdr/I5PA2026090888802), Sep 8, 2026: Boeing 757230. IDG. INOPERATIVE. TOPS SIGNIFICANT REPORT. LEFT IDG INOPERATIVE, ON MEL. REPLACED LH IDG PER APPLICABLE AMM (N888LT)
- [SDR DALA2026090404991](https://openairdocs.org/sdr/DALA2026090404991), Sep 3, 2026: Airbus A330941. GENERATOR. LEAKING. ATB, DUE TO RUBBER ODOR IN THE CABIN, AFTER TAKEOFF. FOUND OIL LEAK FROM THE APU GENERATOR. GENERATOR REPLACED AND INTAK (N419DX)
- [SDR QR9R2026090200001](https://openairdocs.org/sdr/QR9R2026090200001), Sep 2, 2026: Bolkms BK117C2. SENSOR. FAULTY. GEN SPLIT +10 LOW ON #2. A TEST FLIGHT EVAL FOUND #2 GEN AMPS DISPLAY 10 AMPS IN COCKPIT WHILE AMP CLAMP SHOWS 40 AMPS. 
- [SDR YENA2026090100720](https://openairdocs.org/sdr/YENA2026090100720), Aug 31, 2026: Airbus A321271NX. GENERATOR. WARNING MESSAGE. FLT 1534, SFO-BOS. (ETOPS), AFTER ENG SHUTDOWN MX MSG - AC GEN ( CLASS II MAINTENANCE MESSAGES DISPLAYED ON ECAM STATUS  (N4058J)
- [SDR YENA2026090100719](https://openairdocs.org/sdr/YENA2026090100719), Aug 29, 2026: Airbus A321271NX. SEAL. FAILED. FLT # 32, AMS-BOS. (ETOPS), DURING ENG 2 SCHEDULED MX FOUND IDG DRAIN PLUG UNION SEAL DAMAGED, SEAL NOT IN CMM, AMM, EMM (N4083J)
- [SDR QR9R2026082600003](https://openairdocs.org/sdr/QR9R2026082600003), Aug 26, 2026: Bolkms BK117C2. SENSOR. OUT OF LIMITS. GEN AMP DIFFERENCE OF 25 AMPS DURING PRE TAKEOFF CHECKS, ENGINES AT FLIGHT. AVIONICS TROUBLESHOT, BUT PROBLEM REMAINED, 
- [SDR 2026F00183](https://openairdocs.org/sdr/2026F00183), Aug 25, 2026: Airbus A320214. IDG. FAULTED. AFTER ENGINE 1 START, GEN 1 FAULT ON ECAM RESET UNSUCCESFUL (N724AV)
- [SDR 2026FA0000666](https://openairdocs.org/sdr/2026FA0000666), Aug 24, 2026: Boeing 73786J. GCU. INTERMITTENT. DIVERTED FLIGHT TO SLCB IN LEGVVI-LPB FLIGHT 677 DUE TO AC GENERATOR FAIL (FRM 241 010 01 - GEN1 DRIVE LIGHT ILLUMINATED
- [SDR YENA2026082400701](https://openairdocs.org/sdr/YENA2026082400701), Aug 24, 2026: Airbus A321271NX. FILTER. FAULTED. FLT 1178, LAS-BOS. (ETOPS) "INSUFFICENT INFO IN TASK CARD A320-24-21-00-920-802-A. FOR ENG 2 IDG DRAIN/FILL W/FILTER REP (N2156J)
- [SDR YENA2026082400698](https://openairdocs.org/sdr/YENA2026082400698), Aug 22, 2026: Airbus A321271NX. WARNING MESSAGE. ACTIVATED. FLT 411, JFK-LAX. (ETOPS) CLASS II AC GEN MSG ( CLASS II MAINTENANCE MESSAGES DISPLAYED ON ECAM STATUS PAGE OF ECAM SYST (N2105J)
- [SDR YENA2026082100695](https://openairdocs.org/sdr/YENA2026082100695), Aug 19, 2026: Airbus A321271NX. WARNING MESSAGE. ILLUMINATED. FLT # 8583, JFK-MLB. (ETOPS) CLASS II MAINTENANCE MSG AC GEN. OPEN. (N4064J)
- [SDR AALA202608194487](https://openairdocs.org/sdr/AALA202608194487), Aug 18, 2026: Airbus A321211. IDG. OVERHEATED. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED INTO ORD DUE TO THE FLIGHT CREW REPORTING THAT THE LEFT ENGINE IDG OIL  (N187US)
- [SDR YENA2026081700684](https://openairdocs.org/sdr/YENA2026081700684), Aug 17, 2026: Airbus A321271NX. WARNING MESSAGE. ILLUMINATED. FLT 332, MXP-BOS. (ETOPS) "AC GEN MX MSG ( CLASS II MAINTENANCE MESSAGES DISPLAYED ON ECAM STATUS PAGE OF ECAM SYSTEM DI (N4080J)
- [SDR YENA2026081700680](https://openairdocs.org/sdr/YENA2026081700680), Aug 15, 2026: Airbus A321271NX. GENERATOR. FAULT MESSAGE. FLT 411, JFK-LAX. (ETOPS) "CLASS II AC GEN MSG AFTER SHUTDOWN ( CLASS II MAINTENANCE MESSAGES DISPLAYED ON ECAM STATUS P (N2105J)
- [SDR AALA202608185715](https://openairdocs.org/sdr/AALA202608185715), Aug 14, 2026: Airbus A320232. SENSOR. FAULTED. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT DIVERTED TO MSP DUE TO THE FLIGHT CREW REPORTING THAT  (N680AW)
- [SDR AALA202608189996](https://openairdocs.org/sdr/AALA202608189996), Aug 14, 2026: Airbus A320232. IDG. FAILED. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT DIVERTED TO MSP DUE TO THE FLIGHT CREW REPORTING THAT  (N680AW)
- [SDR YENA2026081400669](https://openairdocs.org/sdr/YENA2026081400669), Aug 12, 2026: Airbus A321271NX. GENERATOR. FAULT MESSAGE. FLT 323, JFK-LAX. (ETOPS) "AC GEN CLASS II MX MSG ( CLASS II MAINTENANCE MESSAGES DISPLAYED ON ECAM STATUS PAGE OF ECAM  (N2105J)
- [SDR DXTA2026081409247](https://openairdocs.org/sdr/DXTA2026081409247), Aug 11, 2026: Cndair CL6002B16. IDG. FAILED. ON DESCENT, "GEN 2 OFF" CAS MESSAGE DISPLAYED. WE RAN THE QRH AND WERE UNABLE TO GET THE GENERATOR TO COME BACK ONLINE.  (N228QS)
- [SDR UIEA2026081100740](https://openairdocs.org/sdr/UIEA2026081100740), Aug 10, 2026: Boeing 74747UF. TRU. FAULTED. EICAS MSG "ELEC GEN 3". COMPLIED QRH PROCEDURE(<P>AS A PRECAUTIONARY, R/R TRANSFORMER ASSY T4006 PER AMM 24-23-03/401 &A (N412MC)
- [SDR ABXA20260803346](https://openairdocs.org/sdr/ABXA20260803346), Aug 3, 2026: Boeing 767316. GENERATOR. MALFUNCTIONED. LEFT GEN OFF WITH LEFT BUS TIE LIGHT / ISLN LIGHT ON WHEN POWER ADVANCED FOR TAKEOFF. A/C ABORTED TAKE OFF (ATO) AND RET (N227CY)
- [SDR YENA2026080300640](https://openairdocs.org/sdr/YENA2026080300640), Aug 2, 2026: Airbus A321271NX. IDG. NOT REPORTED. FLT 1534, SFO-BOS. (ETOPS) INSUFFICIENT INFO IN TASK CARD A320-24-21-00-920-802-A FOR ENG 1 IDG DRAIN & FILL, OIL FILTER (N2169J)
- [SDR ABXA20260727337](https://openairdocs.org/sdr/ABXA20260727337), Jul 27, 2026: Boeing 7673P6. GENERATOR. FAULT MESSAGE. AFTER TAKEOFF CLEARANCE WAS RECEIVED PILOT REQUESTED THRUST/N1 TO BE SET. AT APPROXIMATELY 35 KIAS THE CREW RECEIVED THE (N764CK)
- [SDR YENA2026072700624](https://openairdocs.org/sdr/YENA2026072700624), Jul 26, 2026: Airbus A321271NX. WARNING MESSAGE. ILLUMINATED. FLT 346, BCN-BOS. (ETOPS) ACFT GEN CLASS II MESSAGE APPEARED AFTER ENGINE SHUTDOWN ( CLASS II MAINTENANCE MESSAGES DISPL (N4048J)
- [SDR UIEA2026072400646](https://openairdocs.org/sdr/UIEA2026072400646), Jul 24, 2026: Boeing 74746NF. GENERATOR. FAULTED. CREW SET UP IAW DDG 49-11-01. CREW ISOLATED THAT LT PNEUMATIC & RT UTILITY. CREW STARTED NR 4 ENG. DURING START, AT THE  (N454PA)
- [SDR QR9R2026072300002](https://openairdocs.org/sdr/QR9R2026072300002), Jul 23, 2026: Bolkms BK117C2. SENSOR. FLUCTUATES. AFTER REFUEL, DURING PRE-TAKEOFF CHECK, GENERATOR AMPS WERE NOT WITHIN 10 & STAYED AT 15-20+ WITH THE NR 2 BETWEEN 35-40
- [SDR QR9R2026072300001](https://openairdocs.org/sdr/QR9R2026072300001), Jul 23, 2026: Bolkms BK117C2. SENSOR. FAULTY. NR 2 GENERATOR AMPS DROPPED TO 5 AMPS DURING RUN-UP. NR 1 SIDE REMAINED STEADY AT 30 AMPS. REMOVED AND REPLACED NR 2 GEN
- [SDR SWAA2026072358008](https://openairdocs.org/sdr/SWAA2026072358008), Jul 19, 2026: Boeing 7377H4. IDG. WARNING LIGHT. SOURCE OFF LIGHT AND DRIVE LIGHT ILLUMINATED IN CRUZE PER QRH DISCONNECT SWITCH TO DISCONNECT REMOVED AND REPLACED IDG I (N480WN)
- [SDR DALA2026072104276](https://openairdocs.org/sdr/DALA2026072104276), Jul 18, 2026: Airbus A321213. IDG. FAULTED. ATB - DUE TO ELEC IDG 2 OIL OVHT ECAM MESSAGE. IDG #2 PLACED ON MEL. OK TO CONTINUE. LATER, REPLACED NBR 2 ENGINE IDG PE (N327DN)
- [SDR SIMA20260716003](https://openairdocs.org/sdr/SIMA20260716003), Jul 16, 2026: Emb ERJ170200LR. IDG. FAULTED. IDG 2 OFF BUS INDICATION ON EICAS. RAN QRH PROCEDURE UNABLE TO GET IDG2 ONLINE. FLIGHT CREW PLACARD DEFERRED IDG2 OFF BU (N237NN)
- [SDR CALA2026072017891](https://openairdocs.org/sdr/CALA2026072017891), Jul 15, 2026: Boeing 777224. GENERATOR. FAULTED. ELEC BACKUP GEN R EICAS STATUS RIGHT BACKUP GENERATOR OFF DUE TO A PROTECTIVE TRIP. DB BACKUP CONVERTER R&R E2 BUG IAW A (N78003)
- [SDR DALA2026072004235](https://openairdocs.org/sdr/DALA2026072004235), Jul 14, 2026: Airbus A319114. GENERATOR. LEAKING. STINKY FUMES AFTER APU BLEED SELECTED ON GROUND, NO PAX ON BOARD. DEBRIEFED FLIGHT CREW AS PER TASK CARD 0550-2002 STEPS (N345NB)
- [SDR F3LA202607100431](https://openairdocs.org/sdr/F3LA202607100431), Jul 9, 2026: Airbus A321271NX. O-RING. LEAKING. ACFT WAS GROUNDED. DIVERTED TO MCO PER MCC DUE TO OIL QUANTITY LOSS LT ENGINE 14.5 RT ENGINE 20.5 FOR OIL LEAK ON DRAIN  (N630FR)
- [SDR QR9R2026070900001](https://openairdocs.org/sdr/QR9R2026070900001), Jul 9, 2026: Bolkms BK117C2. SENSOR. FLUCTUATES. GEN NR 1 FAILED DURING REFUEL, GENERATOR AMP NOT WITHIN FIVE. ERRATIC AMP FLUCTUATIONS DURING MTF OF 15 TO 20 AMP DIFFER
- [SDR N6WA2026070806](https://openairdocs.org/sdr/N6WA2026070806), Jul 7, 2026: Cndair CL6002C11. FAULT MESSAGE. ILLUMINATED. IDG 1 FAULT 1 MESSAGE (REPEAT). ALREADY ON DEFERRAL PER MEL 24-11-01A CAT A OCN 70102171. (N556GJ)
- [SDR N6WA2026070805](https://openairdocs.org/sdr/N6WA2026070805), Jul 7, 2026: Cndair CL6002C11. FAULT MESSAGE. ILLUMINATED. IDG 1 FAULT MESSAGE B1-007096, IDG1, INTERNAL FAULT. AS PER TELECON WITH MXC, DEFERRED IDG 1 FAULT MESSAGE ON OCN 701021 (N556GJ)
- [SDR AALA202607087645](https://openairdocs.org/sdr/AALA202607087645), Jul 7, 2026: Boeing 7879. GENERATOR. FAULTED. AIRCRAFT WAS NOT GROUNDED: AFTER REACHING CRUISE ELEC A/C BUS R1 EICAS APPEARED WITH PROMPTED MANY OTHER FAILURES ASSOCI (N839AA)
- [SDR DALA2026070603928](https://openairdocs.org/sdr/DALA2026070603928), Jul 4, 2026: Boeing 737932ER. IDG. LEAKING. DIVERTED TO RDU DUE TO LEFT ENGINE GENERATOR FAIL AND SUBSEQUENT APU AUTO SHUTDOWN. FOUND LT IDG OIL COOLER LINE LEAKING (N870DN)

All 4,273: https://openairdocs.org/jasc/2421/reports.md

## Other codes in chapter 24

- [JASC 2400](https://openairdocs.org/jasc/2400): Electrical Power System (1,186 reports)
- [JASC 2410](https://openairdocs.org/jasc/2410): Alternator-Generator Drive (891 reports)
- [JASC 2420](https://openairdocs.org/jasc/2420): AC Generation System (1,302 reports)
- [JASC 2422](https://openairdocs.org/jasc/2422): AC Inverter (557 reports)
- [JASC 2423](https://openairdocs.org/jasc/2423): Phase Adapter (15 reports)
- [JASC 2424](https://openairdocs.org/jasc/2424): AC Regulator (480 reports)
- [JASC 2425](https://openairdocs.org/jasc/2425): AC Indicating System (137 reports)
- [JASC 2430](https://openairdocs.org/jasc/2430): DC Generating System (1,120 reports)
- [JASC 2431](https://openairdocs.org/jasc/2431): Battery Overheat Warning System (82 reports)
- [JASC 2432](https://openairdocs.org/jasc/2432): Battery/Charger System (2,249 reports)
- [JASC 2433](https://openairdocs.org/jasc/2433): DC Rectifier/Converter (197 reports)
- [JASC 2434](https://openairdocs.org/jasc/2434): DC Generator-Alternator (849 reports)
- [JASC 2435](https://openairdocs.org/jasc/2435): Starter-Generator (2,052 reports)
- [JASC 2436](https://openairdocs.org/jasc/2436): DC Regulator (313 reports)
- [JASC 2437](https://openairdocs.org/jasc/2437): DC Indicating System (98 reports)
- [JASC 2440](https://openairdocs.org/jasc/2440): External Power System (169 reports)
- [JASC 2450](https://openairdocs.org/jasc/2450): AC Power Distribution System (872 reports)
- [JASC 2460](https://openairdocs.org/jasc/2460): DC Power Distribution System (608 reports)
- [JASC 2497](https://openairdocs.org/jasc/2497): Electrical Power System Wiring (2,202 reports)

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