# JASC 7921: Engine Oil Cooler

- Type: JASC system/component code (FAA)
- ATA chapter: 79 Engine Oil
- Title in the code table: ENGINE OIL COOLER
- Service difficulty reports: 982
- FAA code table: https://www.faa.gov/sites/faa.gov/files/JASC_Code.pdf#page=68
- Page: https://openairdocs.org/jasc/7921

## What it covers

The component and associated parts that cools engine lubricating oil. Includes brackets, outlet doors, scoops, ducts and louvers, but excludes the temperature regulator. Typical parts are cooler, duct, scoop, door, door actuator, etc.

## Service difficulty reports (982, newest 50)

- [SDR SWAA2026101902771](https://openairdocs.org/sdr/SWAA2026101902771), Oct 17, 2026: Boeing 7378. OIL COOLER. DAMAGED. BIRD STRIKE NR 2 ENGINE, ODOR, NO ABNORMAL INDICATIONS. ODOR WENT AWAY AFTER 30 SECONDS. REMOVED AND REPLACED RIGHT UPPE (N8931L)
- [SDR A6WA202609028910](https://openairdocs.org/sdr/A6WA202609028910), Sep 2, 2026: Cndair CL6002B19. HEAT EXCHANGER. FAULTED. DURING CLIMB NR 2 ENG OIL TEMP REACHED 150'C. C/W QRH -PULLED PWR BACK AND REDUCED PWR. ENG OIL TEMP RETURNED TO NORMAL  (N420AW)
- [SDR UIEA2026080700685](https://openairdocs.org/sdr/UIEA2026080700685), Aug 7, 2026: Boeing 74747UF. HEAT EXCHANGER. FAULTED. ENG 2 OIL TEMP EICAS MSG. FL 380 MAX OIL TEMP APPROX 194. ENG 2 SHUT DOWN. PERFORMED FIM 79-00, FT FIG 109. R & R FUEL/O (N408MC)
- [SDR CALA2026071617838](https://openairdocs.org/sdr/CALA2026071617838), Jul 14, 2026: Boeing 737824. TRANSMITTER. FAULTED. OIL FILTER BYPASS MESSAGE SHOWS ON ENGINE DISPLAY ENG 1 AFTER STARTUP. MESSAGE DISSAPEARED. MESSAGE REAPPEARED AFTER TAK (N76522)
- [SDR DALA2026060503403](https://openairdocs.org/sdr/DALA2026060503403), Jun 4, 2026: Boeing 757232. OIL COOLER. ODOR. CREW REPORTED EXHAUST ODOR IN AFT CABIN ON TAKEOFF AND TOP OF DESCENT. EMERGENCY DECLARED DURING APPROACH. ROAD TRIP. RE (N689DL)
- [SDR DALA2026041702451](https://openairdocs.org/sdr/DALA2026041702451), Apr 15, 2026: Boeing 767332. HEAT EXCHANGER. LEAKING. DIVERTED TO HND FOR LEFT ENGINE OIL QUANTITY DECREASED TO ZERO WITH STABLE TEMPERATURE AND PRESSURE. RIGHT ENGINE ALSO H (N178DN)
- [SDR AALA202601163763](https://openairdocs.org/sdr/AALA202601163763), Jan 15, 2026: Boeing 737823. INDICATOR. FAULTY. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: LOW OIL QUANTITY INDICATION ON THE NUMBER 2 ENGINE, WITH ERRATI (N934NN)
- [SDR AALA202601066384](https://openairdocs.org/sdr/AALA202601066384), Dec 18, 2025: Boeing 737823. LUBRICATION UNIT. LEAKING. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: DURING CRUISE NEAR TOP OF DECENT AT FL210, #1 ENGINE OIL QUANTI (N301NW)
- [SDR AALA202601063655](https://openairdocs.org/sdr/AALA202601063655), Dec 18, 2025: Boeing 737823. SCAVENGE PUMP. LEAKING. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: DURING CRUISE NEAR TOP OF DECENT AT FL210, #1 ENGINE OIL QUANTI (N301NW)
- [SDR 2025FA0000408](https://openairdocs.org/sdr/2025FA0000408), Jun 18, 2025: Cirrus SR22. OIL COOLER. CRACKED. WHILE PERFORMING AN OIL CHANGE, IT WAS DISCOVERED THE DIAGONAL STIFFENERS ON BOTH SIDES OF THE OIL COOLER WERE BROKEN AN (N603DK)
- [SDR CALA2025042104036](https://openairdocs.org/sdr/CALA2025042104036), Apr 18, 2025: Boeing 777222. HEAT EXCHANGER. FAULTED. #2 FUEL/OIL COOLER NEEDS REPLACED AS PRECAUTIONARY MEASURE DUE TO FUEL ODOR IN DRAINED IDG OIL. STARTED TO DISCONNECT TH (N782UA)
- [SDR AALA202504011909](https://openairdocs.org/sdr/AALA202504011909), Mar 21, 2025: Boeing 737823. HEATER. FAILED. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: NUMBER 1 ENGINE FAIL (COMPRESSOR STALL), ENGINE 1 SHUTDOWN BY C (N970NN)
- [SDR 2025F00008](https://openairdocs.org/sdr/2025F00008), Jan 2, 2025: Boeing 73786J. EXCHANGER. LEAKING. ON FLIGHT ENGINE OIL CONSUMPTION HIGH (N368AR)
- [SDR MTNA20241212002](https://openairdocs.org/sdr/MTNA20241212002), Dec 12, 2024: Aerosp ATR42300. OIL COOLER. CRACKED. DURING DECENT OF FLIGHT 7553 DLH-MSP WITH AIRCRAFT N914FX, THE CAPTAIN REPORTED THE NUMBER TWO OIL PRESSURE GAUGE WAS FL (N914FX)
- [SDR HALA20241209352](https://openairdocs.org/sdr/HALA20241209352), Dec 7, 2024: Airbus A330243. HEAT EXCHANGER. LEAKING. ETOPS - DURING PDSC, NOTED OIL COATING #2 ENG FROM HEAT EXCHANGER AREA & OIL LEVEL AT -2. FILLED OIL & RAN #2 ENG @ IDLE (N392HA)
- [SDR QMLA2024081220097](https://openairdocs.org/sdr/QMLA2024081220097), Aug 8, 2024: Bell 407. OIL COOLER. FAILED. DURING TAKEOFF AND INITIAL CLIMB FROM KFMM, THE ENGINE OIL TEMPERATURE EXCEEDED ITS MAXIMUM LIMIT OF 107°C, REACHING A P (N370AM)
- [SDR NACA2024060300001](https://openairdocs.org/sdr/NACA2024060300001), Jun 3, 2024: Boeing 7673BG. VALVE. FAILED. FOUND THE L ENG EEC MSG. REPLACED #1 ENG AIR/OIL HEAT EXCHANGER VALVE IAW AMM 79-21-09 (N563NC)
- [SDR GRTA20240307001](https://openairdocs.org/sdr/GRTA20240307001), Mar 6, 2024: Beech B300. HEAT EXCHANGER. LEAKING. WHILE FLYING AT FL 320 #2 RIGHT SIDE ENGINE LOST OIL PRESSURE INSTANTLY. REQUESTED DIVERT TO KHSV. ON LANDING NOTED OIL  (N531AW)
- [SDR M3XA20231216002](https://openairdocs.org/sdr/M3XA20231216002), Dec 16, 2023: Urocop EC135P2. BYPASS VALVE. UNSERVICEABLE. PILOT REPORTED #1 ENGINE OIL TEMPERATURE EXCEEDANCE OF 129.5. PLACED THE #1 ENGINE TO IDLE AND EXECUTED A SUCCESSFUL PRE (N135WL)
- [SDR ASAA2022121841193](https://openairdocs.org/sdr/ASAA2022121841193), Dec 18, 2022: Boeing 7379. OIL COOLER. CRACKED. FOUND CRACK ON #1 ENGINE SURFACE AIR OIL COOLER LH. GROUNDED - YES. REMOVED AND REPLACED #1 ENG SACOC REF B737-9 AMM 79- (N977AK)
- [SDR GTIA2022111836780](https://openairdocs.org/sdr/GTIA2022111836780), Nov 15, 2022: Airbus A320232. OIL COOLER. FAULT MESSAGE. AFTER TAKEOFF AT ABOUT 600FT ON CLIMBOUT THE #2 ENG ADVISORY OIL AT 5.5 PULSED ONCE WE LEVELED OFF AT 5000 FT OIL QT ROS (N644NK)
- [SDR CALA2022102802987](https://openairdocs.org/sdr/CALA2022102802987), Oct 28, 2022: Boeing 737924ER. OIL FILTER. CLOGGED. ENG OIL FILTER BYPASS SCREEN. TOMC CONTACTED AND WERE ADVICED TO PERFORM REQUIRED INSPECTIONS BEFORE CREATING DIP IRW ST (N69818)
- [SDR CALA2022100702740](https://openairdocs.org/sdr/CALA2022100702740), Oct 7, 2022: Boeing 737824. CHIP DETECTOR. FOD. NO OIL QTY RED OIL PRESS 11 NORMAL LANDING WINDMILL 15 MINUTES FOUND WET AND FINGER TIGHT LOOSE AFT BEARING OIL SUPPLY L (N39297)
- [SDR YENA2022090500869](https://openairdocs.org/sdr/YENA2022090500869), Sep 4, 2022: Airbus A321271N. CHIP DETECTOR. FALSE INDICATION. FLT#20, LHR-JFK. (ETOPS) 'ETOPS GROUND VERIFICATION REQUIRED DUE TO CHIP DETECTION MSG ON ENG 2; ENG #2 GROUND VERIFICAT (N4048J)
- [SDR I5PA2022081668804](https://openairdocs.org/sdr/I5PA2022081668804), Aug 16, 2022: Boeing 757230. SCAVENGE PUMP. FAULTY. L ENG TAIL PIPE FIRE. R/R SCAVENGE PUMP PER AMM 79-21-04. (N688SL)
- [SDR 2022FA0000361](https://openairdocs.org/sdr/2022FA0000361), Jul 20, 2022: Piper PA18. OIL COOLER. CRACKED. ORIGINAL OIL COOLER REPLACED 05/27/2022 DUE TO CRACKED MOUNTING FLANGES. NEW COOLER, S/N 4467 , FAILED AFTER 12 HOURS IN
- [SDR CALA2022071801809](https://openairdocs.org/sdr/CALA2022071801809), Jul 18, 2022: Boeing 757224. LINE. LEAKING. FL360 CLMB-LOW OIL QTY R ENG-FLWD BY R ENG OIL PRESS LT-THEN PRESS INTO RED BND. LEAKED DURING ENGINE RUN.REPLACED OIL L (N12114)
- [SDR CALA2022062901607](https://openairdocs.org/sdr/CALA2022062901607), Jun 29, 2022: Boeing 737924ER. LUBRICATION UNIT. FAULTY. FLIGHT CREW REPORTED OIL FILTER BYPASS ILLUMINATED IN FLIGHT FOR #1 ENGINE PERFORMS FIM 79-05 TASK 817 , NO FAULTS SHOWN (N68453)
- [SDR A6WA202206088189](https://openairdocs.org/sdr/A6WA202206088189), Jun 8, 2022: Cndair CL6002B19. OIL SYSTEM. WARNING MESSAGE. AT CRUISE AT FL280, RECEIVED RT ENG OIL PSI WARNING MESSAGE. OIL PSI WAS FLUCTUATING IN THE GREEN BAND. C/W QRH. REDUCED (N444ZW)
- [SDR AALA202205106206](https://openairdocs.org/sdr/AALA202205106206), May 6, 2022: Airbus A300*. OIL COOLER. DEFECTIVE. AIRCRAFT WAS GROUNDED: #1 ENGINE OIL QUANTITY WENT TO 2.5. ALL OTHER PARAMETERS NORMAL. THEN DROPPED TO 2.0 AND SLOWLY L (N536UW)
- [SDR NACA2022050500001](https://openairdocs.org/sdr/NACA2022050500001), May 5, 2022: Boeing 767323. NONE. NONE. DURING ENGINE #2 BORESCOPE INSPECTION FOUND FUEL PUMP LEAKING. (FUEL IN AND FUEL OUT PORTS) REMOVED AND REPLACED FUEL/OI (N379CX)
- [SDR HALA2022050300097](https://openairdocs.org/sdr/HALA2022050300097), May 2, 2022: Airbus A330243. NONE. NONE. ETOPS - #1 ENG OIL LEAK AT 6 O'CLOCK POSITION UNDER GAS GENERATOR FAIRINGS // PERFORMED ENG RUN LEAK CHK, FOUND TEE FITT (N390HA)
- [SDR A6WA202204308176](https://openairdocs.org/sdr/A6WA202204308176), Apr 30, 2022: Cndair CL6002B19. NONE. NONE. RIGHT ENGINE OIL PRESSURE WENT TO 0 PSI DURING DECENT PLUS RIGHT ENGINE PRESSURE WARN. RAN QRH. RIGHT ENGINE FAILED SHOR (N408AW)
- [SDR WX0A1900010074058](https://openairdocs.org/sdr/WX0A1900010074058), Apr 8, 2022: Airbus A320214. LUBRICATION UNIT. OIL CONSUMPTION. 1 WHILE REACHING 10,000 ' WE GOT A ENG # 2 ECAM ADVISORY OIL QUANTITY (3.5) WE FOLLOWED THE ADVISORY CHECK LIST AND INDI (N223NV)
- [SDR CALA2022011800170](https://openairdocs.org/sdr/CALA2022011800170), Jan 17, 2022: Boeing 737900. FILTER. WARNING MESSAGE. OIL FILTER BYPASS LGT ILUMM ON TAKEOFF ROLL EXTINGUISHED IN AIR CREW REPORTS #2 ENGINE FOR #2 ENGINE FOUND FILTER BYPASS (N57439)
- [SDR 2022F00068](https://openairdocs.org/sdr/2022F00068), Jan 3, 2022: Boeing 737800*. HEAT EXCHANGER. LEAKING. FUEL LEAK AT RIGHT ENGINE OIL/FUEL HEAT EXCHANGER DRAIN AND FUEL SERVO, DURING TRANSIT CHECK, IT WAS DETECTED A FUEL LEA
- [SDR A6WA202112017999](https://openairdocs.org/sdr/A6WA202112017999), Nov 30, 2021: Cndair CL6002B19. NONE. NONE. ON TAKE-OFF REC'D RT ENG OIL WARNING MESSAGE. MESSAGE WAS INTERMITTENT. OIL PSI FLUCTUATED BETWEEN 25 AND 35 PSI. OIL TE (N420AW)
- [SDR CALA2021111102092](https://openairdocs.org/sdr/CALA2021111102092), Nov 11, 2021: Boeing 777222. NONE. LEAKING. REF LOG PAGE 7405211. FOUND #1 ENG AIR/OIL HEAT EXCHANGER LEAKING EXTERNALLY FROM WITHIN THE COOLING FINS, REF PICTURES. (N773UA)
- [SDR 2021F00257](https://openairdocs.org/sdr/2021F00257), Sep 20, 2021: Boeing 737800*. HEAT EXCHANGER. LEAKING. OIL LEAK BY LEFT ENGINE HEAT EXCHANGER OIL FUEL, DURING OVERNIGHT CHECK AT MEX STATION, DUE TO LEFT ENGINE OPERATIONAL T
- [SDR GTIA2021092135999](https://openairdocs.org/sdr/GTIA2021092135999), Sep 18, 2021: Airbus A321231. NONE. NONE. CAPTAIN REPORT FUEL LEAKING FROM #1 ENG , FUEL LEAK INCREASE ON DESCENT-REMOVED FCOC REPLACED PACKING AND REINSTALLED FC (N663NK)
- [SDR 2021FA0000285](https://openairdocs.org/sdr/2021FA0000285), Sep 13, 2021: Cessna 310. HEAT EXCHANGER. DAMAGED. RIGHT ENGINE FUEL LEAK OF HEAT EXCHANGER OIL-FUEL DRAIN, DURING TRANSIT CHECK, IT WAS DETECTED A FUEL LEAK AT RIGHT ENGI (N116BG)
- [SDR ASMF202110001](https://openairdocs.org/sdr/ASMF202110001), Jun 27, 2021: Boeing 737852. LUBRICATION UNIT. FAILED. AIRCRAFT RETURNED OF FLIGHT DUE TO DURING CLIMB, THE RIGHT ENGINE PRESENTED LOW OIL PRESSURE AND QUANTITY; SO FLIGHT CRE (N875AM)
- [SDR ASMF2021F00108](https://openairdocs.org/sdr/ASMF2021F00108), Jun 27, 2021: Boeing 737800*. LUBRICATION UNIT. FAULTED. 28.06.2021 14:32 ENG 2 SHUTDOWN ON FLIGHT DUE LOW OIL PRESSURE AND QUANTITY. AIRCRAFT RETURNED OF FLIGHT DUE TO DURING C (N875AM)
- [SDR HALA2021051100061](https://openairdocs.org/sdr/HALA2021051100061), May 7, 2021: Airbus A321271N. IGNITER. FAULTED. ETOPS - ENG START 2 FAULT. ENG 2 IGN A FAULT. SUCCESSFUL AUTOSTART AFTER SECOND ATTEMPT. BTB// REMOVED AND REPLACED IGN  (N202HA)
- [SDR HALA2021021600019](https://openairdocs.org/sdr/HALA2021021600019), Feb 13, 2021: Airbus A330243. OIL COOLER. DEFECTIVE. ETOPS - ON PDC, FOUND #1 ENG AIR/OIL HEAT EXCHANGE 4073265 LEAKING OIL INTERNALLY. // REMOVED #1 ENG AIR/OIL HEAT EXCHAN (N375HA)
- [SDR M3XA20201019006](https://openairdocs.org/sdr/M3XA20201019006), Oct 19, 2020: Urocop EC135P2. BYPASS VALVE. FAILED. PILOT PERFORMED A PL WITH A PATIENT ON BOARD AND REPORTED NR 2 ENGINE OIL TEMPERATURE ABOVE NORMAL LIMITS IN FLIGHT, PEA (N836CS)
- [SDR MK1Y20200407010](https://openairdocs.org/sdr/MK1Y20200407010), Apr 7, 2020: Boeing 7673P6. OIL COOLER. CRACKED. DURING MAINTENENCE FOUND DEFORMATION WITH CRACK 0.78" ON AIR/OIL COOLER P/N 35E38-5 AFT UPPER AREA. (N153DL)
- [SDR ASAA2020030932355](https://openairdocs.org/sdr/ASAA2020030932355), Mar 4, 2020: Boeing 737990ER. HEAT EXCHANGER. LEAKING. ON WALKAROUND FOUND FUEL LEAKING FROM #2 ENG BOTTOM DRAIN MAST AREA. GROUNDED - YES. RAN #2 ENG AND ACCOMPLISHED B737-90 (N468AS)
- [SDR HALA2019121000511](https://openairdocs.org/sdr/HALA2019121000511), Dec 9, 2019: Airbus A330243. WARNING MESSAGE. FALSE ACTIVATION. ETOPS SIGNIFICANT SYSTEM - ENG 2 AIR EX-CHANGER FAULT. // PERFORMED TSM TASK 79-20-00-810-810-A. BITE CHECK OF FADEC SYS (N374HA)
- [SDR ASAA2019111211285](https://openairdocs.org/sdr/ASAA2019111211285), Nov 11, 2019: Boeing 737990ER. COOLER. LEAKING. FOLLOW-UP TO #2 IDG FREQUENT SERVICING. GROUNDED - YES. ACCOMPLISHED STEPS 1-3 AND FOUND #2 IDG AIR/OIL COOLER LEAKING,  (N442AS)

All 982: https://openairdocs.org/jasc/7921/reports.md

## Other codes in chapter 79

- [JASC 7900](https://openairdocs.org/jasc/7900): Engine Oil System (Airframe Furnished) (261 reports)
- [JASC 7910](https://openairdocs.org/jasc/7910): Engine Oil Storage (Airframe Furnished) (204 reports)
- [JASC 7920](https://openairdocs.org/jasc/7920): Engine Oil Distribution (Airframe Furnished) (734 reports)
- [JASC 7922](https://openairdocs.org/jasc/7922): Engine Oil Temperature Regulator (268 reports)
- [JASC 7923](https://openairdocs.org/jasc/7923): Engine Oil Shutoff Valve (25 reports)
- [JASC 7930](https://openairdocs.org/jasc/7930): Engine Oil Indicating System (1,286 reports)
- [JASC 7931](https://openairdocs.org/jasc/7931): Engine Oil Pressure (1,875 reports)
- [JASC 7932](https://openairdocs.org/jasc/7932): Engine Oil Quantity (217 reports)
- [JASC 7933](https://openairdocs.org/jasc/7933): Engine Oil Temperature (499 reports)
- [JASC 7997](https://openairdocs.org/jasc/7997): Engine Oil System Wiring (236 reports)

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