# JASC 4950: APU Bleed Air System

- Type: JASC system/component code (FAA)
- ATA chapter: 49 Airborne Auxiliary Power
- Title in the code table: APU BLEED AIR SYSTEM
- Service difficulty reports: 949
- FAA code table: https://www.faa.gov/sites/faa.gov/files/JASC_Code.pdf#page=44
- Page: https://openairdocs.org/jasc/4950

## What it covers

The system and components which provide and control a source of pressure and high volume of air for aircraft using systems such as engine starting, cabin air conditioning prior to starting engines. Typical parts are duct, bleed valve, clamp, seal, etc.

## Service difficulty reports (949, newest 50)

- [SDR I5PA2026090968804](https://openairdocs.org/sdr/I5PA2026090968804), Sep 9, 2026: Boeing 757230. VALVE. INTERMITTENT. ETOPS SIGNIFICANT REPORT. APU PNEUMATIC SHUTDOWN VALVE INTERMITTENT. REPLACED APU PNEUMATIC SHUTOFF VALVE PER APPLICABLE (N688SL)
- [SDR I5PA2026090768803](https://openairdocs.org/sdr/I5PA2026090768803), Sep 7, 2026: Boeing 757230. SWITCH. INOPERATIVE. ETOPS SIGNIFICANT REPORT. APU PNEUMATICS INOP. REPLACED APU GEN DPI SWITCH PER APPLICABLE AMM. (N688SL)
- [SDR I5PA2026090288801](https://openairdocs.org/sdr/I5PA2026090288801), Sep 2, 2026: Boeing 757230. APU. INOPERATIVE. ETOPS SIGNIFICANT REPORT, APU PNEUMATICS INOPERATIVE. REPLACED APU PER APPLICABLE AMM (N888LT)
- [SDR YENA2026090400725](https://openairdocs.org/sdr/YENA2026090400725), Sep 1, 2026: Airbus A321271NX. TRANSDUCER. FAILED. FLT 1621, LHR-BOS. (ETOPS) APU BLEED FAULT ( APU BLEED AIR SUPPLY SYSTEM ). R & R APU DIFF PRESSURE TRANSDUCER IAW AMM 4 (N4062J)
- [SDR CALA2026083119034](https://openairdocs.org/sdr/CALA2026083119034), Aug 31, 2026: Boeing 737924. O-RING. DAMAGED. APU AUTO SHUTDOWN CABIN ODOR ASSOCIATED NOTED IN CABIN APU BITE SHOWED ADD OIL. SVCD APU OIL. PERFORMED GVI AND FOUND AP (N73406)
- [SDR SWAA2026082492036](https://openairdocs.org/sdr/SWAA2026082492036), Aug 20, 2026: Boeing 7378. BLEED VALVE. ODOR. WITH APU BLEED ON, FOUL ODOR PRESENT AND ERRATIC DUCT PRESSURE WITH APU BLEED ON. R & R APU BLEED AIR VALVE IAW AMM 49-5 (N8773Q)
- [SDR DALA2026081904741](https://openairdocs.org/sdr/DALA2026081904741), Aug 16, 2026: Boeing 737932ER. O-RING. LEAKING. DURING TAXI IN SMELLED STRONG FUMES IN THE FLIGHT DECK. MAINTENANCE OBSERVED A LOT OF SMOKE FROM L ENG. NO OBSERVED ENGI (N848DN)
- [SDR I5PA2026081388802](https://openairdocs.org/sdr/I5PA2026081388802), Aug 13, 2026: Boeing 757230. ACTUATOR. FAULTED. FLIGHT: MGE502M ETOPS: AIRCRAFT RETURNED TO GATE DUE TO ENGINE STABILIZATION ISSUE AFTER ENGINE START. FOUND APU BLEED P (N888LT)
- [SDR I5PA2026081119303](https://openairdocs.org/sdr/I5PA2026081119303), Aug 11, 2026: Boeing 757223. SENSOR. FAULTY. APU BLEED PRESSURE LOW, REPLACED APU FLOW SENSING MODULE IAW AMM (N193AN)
- [SDR IPXA2026081116362](https://openairdocs.org/sdr/IPXA2026081116362), Aug 11, 2026: Airbus A300F4622R. BLEED AIR SYS. ODOR. UPON TURNING ON APU BLEED AIR, NOTICED A STRONG FUEL ODOR COMING OUT OF THE VENTILATION AREAS IN COCKPIT AND SUPERNUMARY (N126UP)
- [SDR HNAA2026080400646](https://openairdocs.org/sdr/HNAA2026080400646), Aug 4, 2026: Emb EMB145LR. BLEED AIR SYS. LEAKING. CREW NOTIFIED CLT MX OF EXHAUST FUMES IN COCKPIT. CLT MX CREW REPORTED SMELL IN COCKPIT, CABIN NORMAL, FUTHER TROUBLESHO (N655AE)
- [SDR I5PA2026072488803](https://openairdocs.org/sdr/I5PA2026072488803), Jul 24, 2026: Boeing 757230. MODULE. FAULTY. APU INOP. R & R FLOW SENSING MODULE PER AMM, OPS CHECK NORMAL. (N888LT)
- [SDR DALA2026061603604](https://openairdocs.org/sdr/DALA2026061603604), Jun 14, 2026: Boeing 737832. BLEED VALVE. CRACKED. FA.S NOTED BURNING ODOR MID CABIN. FLOOR IS HOT TO THE TOUCH. VERIFIED CRACK ON VALVE NO OTHER DEFECTS AROUND SURROUNDIN (N3757D)
- [SDR IPXA2026042634350](https://openairdocs.org/sdr/IPXA2026042634350), Apr 4, 2026: Boeing 74744AF. CLAMP. CRACKED. CRACKED CLAMP - APU ACOC COOLING DUCT. I.A.W.AMM 49-51-04-004-001 REV116 AND AMM 49-51-04-404-011 REV116 REPLACED THE CL (N575UP)
- [SDR CALA2026021013665](https://openairdocs.org/sdr/CALA2026021013665), Feb 6, 2026: Boeing 737924ER. BLEED VALVE. FAULTED. DUAL BLEED INDICATION, DURING TROUBLESHOOTING IAW TSM 49-55 TASK 803 UP TO AND INCLUDING STEP E. NO FAULTS IN APU BITE.  (N69847)
- [SDR ABXA20260130038](https://openairdocs.org/sdr/ABXA20260130038), Jan 30, 2026: Boeing 767231. PNEUMATIC SYSTEM. FAILED. DURING TAXI OUT, APU PNEUMATICS INOP. A/C RETURNED TO BLOCKS (BTB). MAINTENANCE DEFERRED PER MEL 49-11-1-1. PLACARD INST (N650GT)
- [SDR DALA2026012900704](https://openairdocs.org/sdr/DALA2026012900704), Jan 27, 2026: Airbus A319114. APU. ODOR. DIRTY SOCK SMELL WHEN APU BLEED SELECTED ON. SEE MD-ODI LOG 1420595 FOR WORK PERFORMED AND CORRECTIVE ACTION. (LP: 80356 (N329NB)
- [SDR DALA2025102307761](https://openairdocs.org/sdr/DALA2025102307761), Oct 19, 2025: Boeing 737932ER. BLEED AIR SYS. CONTAMINATED. (LOG 8004328) ODOR ON T/O DISSIPATED WHILE CLIMBING ODOR RETURNED WHILE ON APPROACH THROUGH FL180. ISOLATED ODOR FROM AP (N818DA)
- [SDR I5PA2025092568805](https://openairdocs.org/sdr/I5PA2025092568805), Sep 25, 2025: Boeing 757230. MODULE. FAULTED. APU PNEUMATICS INOP. R & R APU FLOW SENSING MODULE PER AMM. OPS CHECK NORMAL. (N688SL)
- [SDR DALA2025082206260](https://openairdocs.org/sdr/DALA2025082206260), Aug 21, 2025: Airbus A330223. BLEED VALVE. FAULTED. ATO DUE TO ENG THRUST LOSS BLEED CONFIG ECAM MSG WHEN T/O POWER WAS SELECTED. R & R APU BLEED VALVE. OPS CHECK GOOD. (73 (N860NW)
- [SDR YENA2025081200825](https://openairdocs.org/sdr/YENA2025081200825), Aug 11, 2025: Airbus A321271NX. SENSING ELEMENT. FAULTED. FLT#348, LAS-JFK. (ETOPS) "AIR APU BLEED LEAK ECAM FOLLOWED BY ENG 1 BLEED AND PACK 1 FAULT ( APU BLEED AIR SUPPLY SYSTE (N2169J)
- [SDR AALA202508056197](https://openairdocs.org/sdr/AALA202508056197), Aug 3, 2025: Boeing 7378. INLET DOOR. OPEN. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: DURING CLIMBOUT THERE WERE CONTINUOUS AIRFRAME VIBRATIONS AS AI (N329SL)
- [SDR DALA2025072905697](https://openairdocs.org/sdr/DALA2025072905697), Jul 24, 2025: Airbus BD5001A10. DUCT. DAMAGED. APU HIGH PRESSURE BLEED DUCT HAS PLY SEPARATION AT FIRE LOOP STANDOFF, 10 INCHES FWD OF FRAME 85. PER AMDS, REQUIRES CUS (N127DU)
- [SDR DXTA2025062003932](https://openairdocs.org/sdr/DXTA2025062003932), Jun 17, 2025: Cessna 680A. SHUTOFF VALVE. FAULTED. WHEN STARTING ENGINES WITH APU RUNNING, APU BLEED AIR OFF, HEAVY SMELL OF JET EXHAUST IN CABIN AND COCKPIT. CREW NOTICED (N503QS)
- [SDR NACA2025072800002](https://openairdocs.org/sdr/NACA2025072800002), Jun 11, 2025: Boeing 7673BG. WARNING MESSAGE. FALSE ACTIVATION. APU DUCT PRESSURE LOW AT ENG STARTUP. PERFORMED APU DUCT BLEED AIR OPS CHECK IAW B767 AMM 36-00-00-862-025 OPS CHECK GOO (N565NC)
- [SDR CALA2025060505286](https://openairdocs.org/sdr/CALA2025060505286), Jun 2, 2025: Boeing 757224. SURGE VALVE. FAULTED. F/AS REPORTED A THUMPING SOUND AND VIBRATION UNDE R THE AFT GALL EY JUMPSEA T. STARTED B4 GEAR DODEBRIEFED CREW SUSPECT  (N17139)
- [SDR YENA2025060200557](https://openairdocs.org/sdr/YENA2025060200557), Jun 1, 2025: Airbus A321231. BLEED AIR SYS. FAULTED. FLT#2348, LAS-JFK. (AIRCRAFT PERFORMED AN AIR TURN BACK TO LAS) .' AIR APU BLEED FAULT; PERFORMED OPS TEST BMC#1 MIAW AM (N979JT)
- [SDR DALA2025043003336](https://openairdocs.org/sdr/DALA2025043003336), Apr 27, 2025: Airbus BD5001A10. BLEED AIR SYS. ODOR. 800 FT ON APPROACH FO SMELLED DIRTY SOCK ODER , 500 FT CA SMELLED IT AS WELL.APU WAS STARTED ONCE LANDED .R BLEED TURNED (N106DU)
- [SDR CALA2025042304169](https://openairdocs.org/sdr/CALA2025042304169), Apr 21, 2025: Boeing 737824. DUCT. LEAKING. AIR/VENT/GRILLE BY FEET ROW 25/ LEFT SIDE IS HOT AND HAS A BURNI NG SMELL WITH APU BLEED AIR ON AND PACKS RUNNING ROW 25 (N18223)
- [SDR ABXA20250421083](https://openairdocs.org/sdr/ABXA20250421083), Apr 21, 2025: Boeing 767306. BLEED VALVE. WARNING MESSAGE. ON TAXI OUT, APU BLEED VALVE EICAS MSG ILLUMINATED. AIRCRAFT RETURNED TO BLOCKS (BTB). MAINTENANCE DEFERRED APU IAW MEL  (N1427A)
- [SDR AALA202504049752](https://openairdocs.org/sdr/AALA202504049752), Apr 3, 2025: Boeing 737823. BLEED VALVE. FAILED. AIRCRAFT WAS GROUNDED: FLIGHT ATTENDANT REPORTS INTERMITTENT SULFUR LIKE ODOR AROUND AREA OF FORWARD SERVICE DOOR BY COA (N973NN)
- [SDR AALA202504012772](https://openairdocs.org/sdr/AALA202504012772), Mar 24, 2025: Boeing 737823. O-RING. CUT. AIRCRAFT WAS GROUNDED: ABOUT 5 MINUTES AFTER ENGINE START CABIN WAS NOT COOLING DOWN. WE SWITCHED TO MAX COOLING FROM TH (N972AN)
- [SDR YENA2025032400304](https://openairdocs.org/sdr/YENA2025032400304), Mar 23, 2025: Airbus A320232. APU. ODOR. FLT#583, JFK-MCO.' ON DESCENT BELOW 10000 FEET NOTICED STRONG DIRTY SOCK SMELL ON SHORT FINAL FA'S CALLED TO COMPLAIN OF (N517JB)
- [SDR HALA20250220066](https://openairdocs.org/sdr/HALA20250220066), Feb 19, 2025: Airbus A330243. DUCT. DAMAGED. ETOPS - FOUND APU BLEED DUCT DAMAGED BETWEEN COMPRESSOR AND SURGE VALVE. REMOVED AND REPLACED APU BLEED DUCT BETWEEN COM (N388HA)
- [SDR I5PA2025021768804](https://openairdocs.org/sdr/I5PA2025021768804), Feb 17, 2025: Boeing 757230. SURGE VALVE. FAULTY. FLT NO: N/A (MX INSP) ESI - APU AUTO SHUTDOWN. R/R APU SURGE VALVE. OPS CHECK NORMAL. (N688SL)
- [SDR I5PA2025021768803](https://openairdocs.org/sdr/I5PA2025021768803), Feb 17, 2025: Boeing 757230. APU. FAULTY. FLT NO: N/A (MX INSP) ESI - APU BLEED INOP. R/R APU PER AMM 49-11-01. OPS CHECK NORMAL. (N688SL)
- [SDR I5PA2025021068801](https://openairdocs.org/sdr/I5PA2025021068801), Feb 10, 2025: Boeing 757230. CHECK VALVE. WORN. FLT NO: N/A (MX INSP). ESI - APU CHECK VALVE WORN. R/R APU BLEED AIR CHECK VALVE PER AMM 36-11-11. (N688SL)
- [SDR ABXA20250206034](https://openairdocs.org/sdr/ABXA20250206034), Feb 6, 2025: Boeing 7673P6. BLEED AIR SYS. FAULTED. DURING TAXI WHILE STARTING ENGINE APU DOES NOT HAVE PNEUMATIC AIR FOR ENGINE START,A/C THEN RETURNED TO THE GATE (BTB) A (N762CK)
- [SDR I5PA2025012768802](https://openairdocs.org/sdr/I5PA2025012768802), Jan 27, 2025: Boeing 757230. MODULE. FAULTY. FLT: N/A (MX INSP) ESI - NO APU BLEED. REMOVED AND REPLACED FLOW SENSING MODULE PER AMM. (N688SL)
- [SDR YENA2025012200094](https://openairdocs.org/sdr/YENA2025012200094), Jan 20, 2025: Airbus A320232. BLEED AIR SYS. ODOR. FLT#743, JFK-AUA. 'DIRTY SOCK SMELL REPORTED BY FLIGHT ATTENDANT FROM MID TO AFT CABIN ( APU BLEED AIR SUPPLY SYSTEM );  (N613JB)
- [SDR AALA202501084835](https://openairdocs.org/sdr/AALA202501084835), Jan 7, 2025: Boeing 737823. APU. ODOR. AIRCRAFT WAS GROUNDED: WHILE DESCENDING THE APU WAS STARTED AND A STRONG BURNING ODOR WAS DETECTED. IT SMELT VERY SIMILA (N887NN)
- [SDR YENA2024122701637](https://openairdocs.org/sdr/YENA2024122701637), Dec 24, 2024: Airbus A321231. BLEED AIR SYS. ODOR. FLT#1269, BOS-FLL. 'ON DESCEND THRU 5000 FEET WE ENCOUNTERED DIRTY SOCK SMELL; ACCOMPLISHED INFO NOTICE 2017-TO15K FOUND (N949JT)
- [SDR ABXA20241211251](https://openairdocs.org/sdr/ABXA20241211251), Dec 11, 2024: Boeing 767338. APU. FAULTED. AFTER DE-ICE APU WOULD NOT PRODUCE ENOUGH AIR FOR START AC RETURNED TO GATE (BTB) AND MTX GROUNDED AC . AND DEFERRED APU (N371CM)
- [SDR ABXA20241210250](https://openairdocs.org/sdr/ABXA20241210250), Dec 10, 2024: Boeing 767383. APU. FAULTED. APU AIR PRESSURE LOW DURING START (11 PSI)DURING LH ENGINE START HUNG AT 25% N2 ON TAXI OUT. AC RETURNED TO GATE (BTB) . (N220CY)
- [SDR CVGA20241212001](https://openairdocs.org/sdr/CVGA20241212001), Dec 7, 2024: Cessna 560XL. BLEED AIR SYS. FAULTED. JET FUEL SMELL COMING INTO AIRCRAFT FROM THE AIR VENTS. MORE PROMINENT FROM THE OVERHEAD COLD AIR VENTS THAN THE CONDITI (N512UP)
- [SDR YENA2024120201522](https://openairdocs.org/sdr/YENA2024120201522), Dec 1, 2024: Airbus A321231. APU. SMOKE. FLT#255, JFK-PLS. 'LEVEL 1 FUME EVENT SOCK SMELL FROM ROWS 27 AND BACK OCCURRED DURING DESCENT ( APU BLEED AIR SUPPLY SY (N949JT)
- [SDR DALA2024120311390](https://openairdocs.org/sdr/DALA2024120311390), Nov 30, 2024: Airbus A319114. ABNORMAL. SHIP 3102 INTERMITTANT ODOR DETECTED ON DECENT AND AGAIN ON GROUND FOUND RESIDUAL DE-ICE FLUID BY APU INTAKE. CORRECTIVE (N302NB)
- [SDR AALA202411277891](https://openairdocs.org/sdr/AALA202411277891), Nov 25, 2024: Airbus A319112. COOLING FAN. LEAKING. AIRCRAFT WAS GROUNDED: AFTER APU BLEED AIR ON, DIRTY SOCKS SMELL IN ENTIRE AIRCRAFT DURING CRUISE. NO INJURIES REPORTED. (N722US)
- [SDR YENA2024112501497](https://openairdocs.org/sdr/YENA2024112501497), Nov 23, 2024: Airbus A321231. BLEED AIR SYS. ODOR. FLT#771, BOS-CUN. 'INBOUND FA'S ALL REPORT A FUME IN THE CABIN UPON LANDING ( APU BLEED AIR SUPPLY SYSTEM ).' (SUPPLEMEN (N949JT)
- [SDR ABXA20241121230](https://openairdocs.org/sdr/ABXA20241121230), Nov 21, 2024: Boeing 767281. CONTROLLER. FAULTED. DURING TAXI APU NOT PRODUCING BLEED AIR AC RETURNED TO BLOCK (BTB). MTX GROUNDED AC , RESET AND CLEANED FAULT ON APU CON (N783AX)

All 949: https://openairdocs.org/jasc/4950/reports.md

## Other codes in chapter 49

- [JASC 4900](https://openairdocs.org/jasc/4900): Airborne Auxiliary Power Unit (APU) System (1,839 reports)
- [JASC 4910](https://openairdocs.org/jasc/4910): APU Cowling/Containment (950 reports)
- [JASC 4920](https://openairdocs.org/jasc/4920): APU Core Engine (2,429 reports)
- [JASC 4930](https://openairdocs.org/jasc/4930): APU Engine Fuel and Control (1,087 reports)
- [JASC 4940](https://openairdocs.org/jasc/4940): APU Start/Ignition System (1,424 reports)
- [JASC 4960](https://openairdocs.org/jasc/4960): APU Controls (383 reports)
- [JASC 4970](https://openairdocs.org/jasc/4970): APU Indicating System (272 reports)
- [JASC 4980](https://openairdocs.org/jasc/4980): APU Exhaust System (164 reports)
- [JASC 4990](https://openairdocs.org/jasc/4990): APU Oil System (2,648 reports)
- [JASC 4997](https://openairdocs.org/jasc/4997): APU System Wiring (226 reports)

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