# JASC 7520: Engine Cooling System

- Type: JASC system/component code (FAA)
- ATA chapter: 75 Air
- Title in the code table: ENGINE COOLING SYSTEM
- Service difficulty reports: 328
- FAA code table: https://www.faa.gov/sites/faa.gov/files/JASC_Code.pdf#page=65
- Page: https://openairdocs.org/jasc/7520

## What it covers

The portion of the engine compressor bleed air system which is used to ventilate engine compartments and accessories. Does not include the engine bleed control valve which is filed in JASC code 7532. Typical parts are jet pumps, vortex generators, valve, actuator, and associated parts and circuitry used to control bleed air to engine accessory cooling systems.

## Service difficulty reports (328, newest 50)

- [SDR YENA2026082400696](https://openairdocs.org/sdr/YENA2026082400696), Aug 21, 2026: Airbus A321271NX. WARNING MESSAGE. ILLUMINATED. FLT 72, EDI-JFK. (ETOPS) AFTER LANDING, ENG 2 TURB COOL FAULT. CAUTION MSG ( TCC/TACC VALVE ). OPEN (N2193J)
- [SDR SWAA2026081028117](https://openairdocs.org/sdr/SWAA2026081028117), Aug 6, 2026: Boeing 7378. BRACKET. CRACKED. NR 1 ENGINE LPTACC LOWER MANIFOLD SUPPORT BRACKET AT 9 O'CLOCK POSITION WAS CRACKED AT FWD ATTACH POINT. R & R NR 1 ENGI (N8893L)
- [SDR SWAA2026081089026](https://openairdocs.org/sdr/SWAA2026081089026), Aug 6, 2026: Boeing 7378. BRACKET. CRACKED. NR 1 ENGINE, LPTACC LOWER MANIFOLD SUPPORT BRACKET JUST BELOW THE 9 O'CLOCK POSITION WAS CRACKED AT FWD ATTACH POINT. R  (N8893L)
- [SDR SWAA2026081087653](https://openairdocs.org/sdr/SWAA2026081087653), Aug 6, 2026: Boeing 7378. BRACKET. CRACKED. NR 1 ENGINE, LPTACC LOWER MANIFOLD SUPPORT BRACKET AT 3 O'CLOCK POSITION WAS CRACKED AT FWD ATTACH POINT. R & R THE NR 1 (N8893L)
- [SDR SWAA2026072344101](https://openairdocs.org/sdr/SWAA2026072344101), Jul 22, 2026: Boeing 7378H4. VALVE. LEAKING. NR 1 ENGINE STEADY FUEL LEAK AFTER ENGINE START. REMOVED AND REPLACED HTPACC PER AMM 75-21-01. (N8509U)
- [SDR AALA202606123906](https://openairdocs.org/sdr/AALA202606123906), Jun 10, 2026: Airbus A321253NX. LINE. DISCONNECTED. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO LAX DUE TO THE FLIGHT CREW REPORTING THAT  (N466AN)
- [SDR UIEA2026032700108](https://openairdocs.org/sdr/UIEA2026032700108), May 12, 2026: Boeing 7673Y0. SWITCH. SHORTED. DURING PREPARATION FOR ENG #2 COOLING BAROMETRIC SWITCH, OPS CHK FOUND DAMAGE TO A SCREW AT NACELLE ZONE VENT SOV. AFTER (N1619A)
- [SDR DALA2026031001643](https://openairdocs.org/sdr/DALA2026031001643), Mar 8, 2026: Boeing 717200. VALVE. BINDING. SHIP 9522 CREW REPORTS STRONG DIRTY SOCK SMELL IN BACK OF AIRCRAFT. CORRECTIVE ACTION: FOUND #2 ENG SOURCE R/R #2 ENG BU (N963AT)
- [SDR BAGA2026021900004](https://openairdocs.org/sdr/BAGA2026021900004), Feb 16, 2026: Airbus BD5001A11. SHUTOFF VALVE. FAILED. RIGHT NEACELLE OVERHEAT CAUTION MESSAGE IN FLIGHT. CLEARED AFTER RUNNING CHECKLIST. GOT MESSAGE AGAIN AFTER GOING BACK T (N219BZ)
- [SDR YENA2025101601041](https://openairdocs.org/sdr/YENA2025101601041), Oct 16, 2025: Airbus A321271NX. VALVE. FAULTED. FLT#1178, LAS-BOS. (ETOPS) CR 2 ALERT (APPROVAL REQUIRED FOR RESOLUTION) ENG 2 TURB COOL FAULT AFTER LANDING ( TCC/TACC  (N2193J)
- [SDR BAGA2025081100004](https://openairdocs.org/sdr/BAGA2025081100004), Aug 8, 2025: Airbus BD5001A11. SHUTOFF VALVE. FAILED. OIL ODOR IN FWD CABIN. R & R RT ENGINE BAV & ENGINE BUFFER AIR SHUTOFF VALVE. OPS CHECKED GOOD. NO MEDICAL ATTENTION NEE (N220BZ)
- [SDR SWAA2025072895274](https://openairdocs.org/sdr/SWAA2025072895274), Jul 24, 2025: Boeing 7378H4. VALVE. LEAKING. FUEL LEAKING #2 ENGINE COWLING<[01] R-R?D #2 ENG HPTACC VALVE <BR>& LEAK/OPS CHECK GOOD PER AMM 75-21-01<BR><BR>E142282 (N8310C)
- [SDR IPXA202507074238](https://openairdocs.org/sdr/IPXA202507074238), Jul 5, 2025: Boeing 76734AF. LINK. WORN. WORN OUT SUPPORT LINK, NO.2 ENG R/H HPT CASE COOLING FWD DUCT UPPER SIDE, NEAR FUEL SUPPLY LINE. (REPLACE) OK TO WORK (N325UP)
- [SDR IPXA2025070762480](https://openairdocs.org/sdr/IPXA2025070762480), Jul 4, 2025: Boeing 76734AF. MANIFOLD. BROKEN. BROKEN - MANIFOLD, NO.2 ENG LPT CASE COOLING, NEAR 11:00 AREA. I.A.W. AMM 75-24-03-004-050-H00 AND 75-24-03-404-037-H00, (N325UP)
- [SDR AALA202507020782](https://openairdocs.org/sdr/AALA202507020782), Jun 30, 2025: Airbus A321253NX. CONTROL VALVE. FAULTED. AIRCRAFT WAS NOT GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO LAX DUE TO THE FLIGHT CREW REPORTING A (N411AN)
- [SDR AALA202507010782](https://openairdocs.org/sdr/AALA202507010782), Jun 30, 2025: Airbus A321253NX. WARNING MESSAGE. ILLUMINATED. AIRCRAFT WAS NOT GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO LAX DUE TO THE FLIGHT CREW REPORTING A (N411AN)
- [SDR SWAA2025070186683](https://openairdocs.org/sdr/SWAA2025070186683), Jun 29, 2025: Boeing 7377H4. VALVE. FAULTED. #1 ENG EGT ROSE RAPIDLY. #1 ENG EGT YELLOW ALERT FLASHED FOR 30 SECONDS. RETARTED #1 ENG THROTTLE; EGT RETURNED TO NORMA (N239WN)
- [SDR I5PA2025061068802](https://openairdocs.org/sdr/I5PA2025061068802), Jun 10, 2025: Boeing 757230. ACTUATOR. LEAKING. FOUND FUEL LEAK AT THE LH ENG TURBINE COOLING ACTUATER. R/R LH ENG TURBINE COOLING ACTUATER (TCA) PER AMM. OPS CHECK NOR (N688SL)
- [SDR SWAA2025042124867](https://openairdocs.org/sdr/SWAA2025042124867), Apr 15, 2025: Boeing 7377H4. SUPPORT BRACKET. CRACKED. #2 ENGINE LPTACC COOLING AIR TUBE ANGLE SUPPORT BRACKET SEPARATED AT FWD EDGE AT THE 4 0 CLOCK POSITION <[01]. REMOVED A (N472WN)
- [SDR YENA2025041400397](https://openairdocs.org/sdr/YENA2025041400397), Apr 11, 2025: Airbus A321271NX. CHECK VALVE. WORN. FLT#1124, LAX-JFK. (ETOPS) ON DESCENT PASSING FL180 ENG 2 AIR SYS FAULT ECAM ANN AND QRH PROCEDURE COMPLETED -EVENTUALLY (N2142J)
- [SDR YENA2025040700369](https://openairdocs.org/sdr/YENA2025040700369), Apr 6, 2025: Airbus A321271NX. SENSOR. FAILED. FLT#623, JFK-LAX. (ETOPS) 'ENG 2 AIR SYS FAULT ECAM ATCRUISE FL 340; REMOVED AND REPLACED BUFFER AIR VALVE PRESSURE SENS (N2142J)
- [SDR YENA2025040400365](https://openairdocs.org/sdr/YENA2025040400365), Apr 2, 2025: Airbus A321271NX. BUFFER VALVE. FAILED. FLT#2073, JFK-LAX. (ETOPS) 'ON DESCENT ENG 2 AIR SYS FAULT; ACCOMPLISHED TSM 75-26-00-810-818A STEP 7 REMOVED AND REPLAC (N2142J)
- [SDR NACA2025032800002](https://openairdocs.org/sdr/NACA2025032800002), Mar 28, 2025: Boeing 767323. COOLING DUCT. CRACKED. #2 ENG MANIFOLD COOLING DUCT CRACK AT 7 AND 12 OCLOCK POSIITION. REPLACED 2 EA LPT COOLING AIR MANIFOLD (N321CM)
- [SDR NACA2025031100012](https://openairdocs.org/sdr/NACA2025031100012), Mar 11, 2025: Boeing 767323. MANIFOLD. CRACKED. RIGHT ENGINE LPD MANIFOLD COOLING SKIN CRACK LEFT SIDE. REPLACED THE #10 LPT COOLING AIR MANIFOLD (N321CM)
- [SDR DALA2025030501715](https://openairdocs.org/sdr/DALA2025030501715), Mar 4, 2025: Boeing 717200. VALVE. STIFF. SHIP 9519 -ATB/FUME/DE- DURING CLIMB OUT AT ABOUT 10K FEET, THE FLIGHT CREW DECLARED AN EMERGENCY WITH ATC AND RETURNED  (N960AT)
- [SDR AALA202410285317](https://openairdocs.org/sdr/AALA202410285317), Oct 23, 2024: Airbus A319112. DUCT SEAL. LEAKING. AIRCRAFT WAS GROUNDED: AFTER TAKEOFF INTERMITTENT ENGINE FIRE INDICATION ENGINE NUMBER2. DURING EXECUTION OF COMPANY PRO (N704US)
- [SDR IPXA2024062589422](https://openairdocs.org/sdr/IPXA2024062589422), Jun 11, 2024: Boeing 76734AF. STRAP. CRACKED. STRAP, NR 1 ENGINE LT HPT COOLING DUCT REAR FRAME FLANGE SUPPORT BRACKET RETAINING. IAW AMM 70-50-00-912-001-H00, REV.14 (N353UP)
- [SDR HALA20240513131](https://openairdocs.org/sdr/HALA20240513131), May 11, 2024: Airbus A330243. THERMOSTAT. FAULTED. ETOPS - ON DESCENT # 2 PACK OVERHEAT ECAM DISPLAYED FOLLOWED BY ENG 2 BLEED FAULT ECAM. COMPLETED ECAM ACTIONS. PERFORME (N360HA)
- [SDR NACA2024050800002](https://openairdocs.org/sdr/NACA2024050800002), May 8, 2024: Boeing 7673BG. SWITCH. FAILED. FOUND THE BAROMETRIC SWITCH S495 MALFUNCTION. REMOVED AND REPLACED #2 ENG BAROMETRIC SWITCH S495 AS PER AMM 75-23-04. PA (N563NC)
- [SDR NACA2024050700005](https://openairdocs.org/sdr/NACA2024050700005), May 7, 2024: Boeing 7673BG. VALVE. FAILED. L NAC COOLING VALVE TEST FAIL. REMOVED AND REPLACED THE NAC COOLING VALVE AS PER B767-300 AMM 75-23-02. PART IS UNKNOWN  (N563NC)
- [SDR HALA20240506126](https://openairdocs.org/sdr/HALA20240506126), May 3, 2024: Airbus A330243. PRECOOLER. FAILED. ETOPS - AIR ENG 1 BLEED HI TEMP DURING DESCENT. REMOVED AND REPLACED #1 ENG PRE-COOLER PER AMM 36-11-42. LEAK CHECK GOOD (N389HA)
- [SDR NACA2024043000003](https://openairdocs.org/sdr/NACA2024043000003), Apr 30, 2024: Boeing 7673BG. VALVE. FAILED. STATUS ON FINAL RH ENG A/O VALVE. REPLACED AIR/OIL VALVE IAW AMM 79-21-09 IDLE LEAK TEST GOOD. (N565NC)
- [SDR NACA2024042000003](https://openairdocs.org/sdr/NACA2024042000003), Apr 20, 2024: Boeing 7673BG. WARNING MESSAGE. ILLUMINATED. RH ENG A/O VALVE STATUS MESSAGE. PERFORME BITE TEST, OPS CHECK GOOD NO MSG IAW FIM 71-01 FT 803. (N30565)
- [SDR NACA2024042000002](https://openairdocs.org/sdr/NACA2024042000002), Apr 20, 2024: Boeing 7673BG. VALVE. FAILED. RH ENGINE A/O VALVE STATUS MESSAGE. REPLACED AIR/OIL VALVE IAW AMM 79-21-09 OPS CHECK AND LEAK CHECK GOOD. (N565NC)
- [SDR ASAA2023102945873](https://openairdocs.org/sdr/ASAA2023102945873), Oct 29, 2023: Boeing 737990ER. UNKNOWN. UNKNOWN. DURING TASK CARD 78273000 FOUND #2 ENGINE ECONOMIC RECENT FAULT 75-10362 "THE HPTACC POSITION SIGNAL IS OUT OF RANGE. GR (N481AS)
- [SDR ASAA2023102345816](https://openairdocs.org/sdr/ASAA2023102345816), Oct 23, 2023: Boeing 737990ER. UNKNOWN. UNKNOWN. FOUND 4 ECONOMIC FAULTS ON #2 ENG HPTACC SIGNALS RECORDED FAULTS: 75-10462, 75-20412, 75-10412, 75-10362. GROUNDED - YES (N493AS)
- [SDR ASAA2023102345792](https://openairdocs.org/sdr/ASAA2023102345792), Oct 23, 2023: Boeing 737890. UNKNOWN. UNKNOWN. WHILE PERFORMING TASK CARD 78273000, FOUND ENGINE 2 FAULTMSG NBR: 75-10462 THE HPTACC DEMAND AND POSITION SIGNALS DISAGR (N506AS)
- [SDR ASAA2023092245252](https://openairdocs.org/sdr/ASAA2023092245252), Sep 22, 2023: Boeing 737890. UNKNOWN. UNKNOWN. #2 ENGINE DRIPPING FUEL. OPENED #2 FAN COWL PER B737-800 AMM 71-11-02. INSPECTED ENGINE DRAINS. FOUND HPTACC VALVE DRIPP (N590AS)
- [SDR ASAA2023091745220](https://openairdocs.org/sdr/ASAA2023091745220), Sep 17, 2023: Boeing 737990ER. UNKNOWN. UNKNOWN. REF LP 60608120. AFTER PERFORMING IDLE RUN TEST FOR STARTER INSTALLATION AND CLOSING FAN COWLS FOUND STEADY FUEL DRIPPIN (N409AS)
- [SDR ASAA2023081644639](https://openairdocs.org/sdr/ASAA2023081644639), Aug 16, 2023: Boeing 737990ER. UNKNOWN. UNKNOWN. WHILE ACCOMPLISHING T/C78273000 FAULT CODE 75-10462 APPEARED ON #2 ENGINE. THE HPTACC DEMAND AND POSITION SIGNALS DISAGR (N493AS)
- [SDR ASAA2023072844315](https://openairdocs.org/sdr/ASAA2023072844315), Jul 28, 2023: Boeing 737990ER. UNKNOWN. UNKNOWN. WHILE PERFORMING T/C 78273000 FOUND SHORT TIME FAULT 75-30602 THE TBV POSITIONS SIGNALS DISAGREE ON #2 ENG. GROUNDED - Y (N419AS)
- [SDR ASAA2023072544233](https://openairdocs.org/sdr/ASAA2023072544233), Jul 25, 2023: Boeing 737990ER. UNKNOWN. UNKNOWN. REFERENCE TASK CARD 78273000, #2 ENGINE HAS LONG TIME FAULT NUMBER 75-10592, THE TBV POSITION SIGNAL IS OUT OF RANGE. GR (N419AS)
- [SDR ASAA2023071744079](https://openairdocs.org/sdr/ASAA2023071744079), Jul 17, 2023: Boeing 737890. UNKNOWN. UNKNOWN. WHILE ACCOMPLISHING T/C 78273000 FOUND ENG #2 ECONOMIC FAULT 75-10362 THE HPTACC POSITION SIGNALS IS OUT OF RANGE. GROUN (N512AS)
- [SDR ASAA2023071744078](https://openairdocs.org/sdr/ASAA2023071744078), Jul 17, 2023: Boeing 737890. UNKNOWN. UNKNOWN. WHILE ACCOMPLISHING T/C 78273000 FOUND ENG #2 ECONOMIC FAULT 75-30412. THE HPTACC POSITION SIGNALS DISAGREE. GROUNDED -  (N512AS)
- [SDR ASAA2023072174077](https://openairdocs.org/sdr/ASAA2023072174077), Jul 17, 2023: Boeing 737890. UNKNOWN. UNKNOWN. WHILE ACCOMPLISHING T/C 78273000 FOUND ENG #2 ECONOMIC FAULT 75-20462. THE HPTACC DEMAND AND POSITION SIGNALS DISAGREE.  (N512AS)
- [SDR ASAA2023061443694](https://openairdocs.org/sdr/ASAA2023061443694), Jun 14, 2023: Boeing 737890. UNKNOWN. UNKNOWN. #1 ENGINE LONG TIME FAULT. MSG NBR 75-10591. THE TBV POSITION SIGNAL IS OUT OF RANGE. GROUNDED - YES. ON DEFERRAL. (N564AS)
- [SDR ASAA2023060643772](https://openairdocs.org/sdr/ASAA2023060643772), Jun 6, 2023: Boeing 737890. VALVE. FAULTY. TECH SERVICE REQUEST. GE DIAGNOSTICS IS REPORTING #1 ENGINE HPTACC FAULTS WITH COORESPONDING TREND SHIFTS. PRI2CNR 20230 (N583AS)
- [SDR DALA2023051703936](https://openairdocs.org/sdr/DALA2023051703936), May 16, 2023: Airbus A320211. UNKNOWN. UNKNOWN. SHIP 3230 #1 ENGINE FAILED FADEC MOTORING TEST DURING PREFLIGHT. CH 1B FAULT-LPTC VLV. CORRECTIVE ACTION: INSTALLED NEW  (N330NW)
- [SDR ASAA2023040842829](https://openairdocs.org/sdr/ASAA2023040842829), Apr 8, 2023: Boeing 737890. VALVE. LEAKING. CREW REPORTS FUEL LEAK UNDER #2 ENGINE. GROUNDED - YES. REMOVED & REPLACE HPTACC OF ENG 32 IAW B737-800 AMM 75-21-01. (N506AS)
- [SDR ASAA2023032442586](https://openairdocs.org/sdr/ASAA2023032442586), Mar 24, 2023: Boeing 737890. VALVE. FAULTY. REPLACE #1 TBV DUE TO HISTORY OF FAULTS. GROUNDED - YES. REPLACED J6 HARNESS REF 73-21-06. REPLACED TBV IN REF TO B737-8 (N563AS)

All 328: https://openairdocs.org/jasc/7520/reports.md

## Other codes in chapter 75

- [JASC 7500](https://openairdocs.org/jasc/7500): Engine Bleed Air System (1,369 reports)
- [JASC 7510](https://openairdocs.org/jasc/7510): Engine Anti-Icing System (868 reports)
- [JASC 7530](https://openairdocs.org/jasc/7530): Compressor Bleed Control (902 reports)
- [JASC 7531](https://openairdocs.org/jasc/7531): Compressor Bleed Governor (21 reports)
- [JASC 7532](https://openairdocs.org/jasc/7532): Compressor Bleed Valve (1,773 reports)
- [JASC 7540](https://openairdocs.org/jasc/7540): Bleed Air Indicating System (108 reports)
- [JASC 7597](https://openairdocs.org/jasc/7597): Engine Bleed Air System Wiring (71 reports)

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