# JASC 7721: Cylinder Head Temperature (CHT) Indicating System

- Type: JASC system/component code (FAA)
- ATA chapter: 77 Engine Indicating
- Title in the code table: CYLINDER HEAD TEMP (CHT) INDICATING
- Service difficulty reports: 62
- FAA code table: https://www.faa.gov/sites/faa.gov/files/JASC_Code.pdf#page=67
- Page: https://openairdocs.org/jasc/7721

## What it covers

The instruments which indicates temperature measured at reciprocating engine cylinder heads. Typical parts are indicator, case, dial, needle, thermocouple lead, sensor, and connector, etc.

## Service difficulty reports (62, newest 50)

- [SDR SWAA2024080823958](https://openairdocs.org/sdr/SWAA2024080823958), Aug 5, 2024: Boeing 7377H4. PROBE. FAILED. RED BOX ON SHUTDOWN IN #2 ENG. EGT REDLINE LIMIT EXCEEDED ON TAKEOFF. DISCONNECTED A/T AND REDUCED THRUST; NO FURTHER IN (N235WN)
- [SDR 2023FA0000564](https://openairdocs.org/sdr/2023FA0000564), Sep 21, 2023: Cirrus SR22T. CYLINDER HEAD. CRACKED. CRACKED #5 CYLINDER HEAD (N748CM)
- [SDR CALA2023072602333](https://openairdocs.org/sdr/CALA2023072602333), Jul 22, 2023: Boeing 737900ER. THERMOCOUPLE. OUT OF RANGE. R ENG HAD RAPID EGT INCREASE TO CAUTION REDUCED THRUST TO 74 N1 AND STABILIZED 77-20862 AND 77-20872. UPDATED MAA CODE F (N47414)
- [SDR 2023F00148](https://openairdocs.org/sdr/2023F00148), Feb 23, 2023: Boeing 7378. PROBE. DEFECTIVE. DURANTE CARRETERO NO ARRANCO MOTOR 2, SE REEMPLAZA PROBETA T49-5, DE ACUERDO A EL AMM 77-21-01
- [SDR SWIA20230205](https://openairdocs.org/sdr/SWIA20230205), Feb 5, 2023: Emb ERJ170200LR. NOT REPORTED. FAILED. BEFORE DEPARTURE WE NOTICED SOME NICKS ON THE N1 BLADES FOR ENGINE 2. WE HAD MAINTENANCE COME OUT AND CORRECT IT. WHILE  (N610CZ)
- [SDR CALA2023010900064](https://openairdocs.org/sdr/CALA2023010900064), Jan 9, 2023: Boeing 737824. HMU. INOPERATIVE. LEFT ENGINE UNABLE TO PRODUCE MORE THAN 90.1 WITH A REQUEST FOR MAX RIGHT ENG 100.3 CLOSE TO 80 DEGREES AT IDLE. REMOVED (N78509)
- [SDR OZCA340084221207](https://openairdocs.org/sdr/OZCA340084221207), Dec 7, 2022: Saab SF340A. PERISEAL. UNSERVICEABLE. #2 ENGINE IN CRUISE, ITT OUT OF LIMITS. C/W QRH. - REMOVED AND REPLACED R/H SIDE UNDER WING FLAP PERI-SEAL IAW SF340A AM (N671BC)
- [SDR SWIA202266912](https://openairdocs.org/sdr/SWIA202266912), Nov 27, 2022: Cndair CL6002B19. BLADES. DAMAGED. NR 2 ENGINE SEIZED ON CLIMB OUT. LOUD AGGRESSIVE BANG FROM ENGINE. ITT IN THE RED. N1 ROLLED BACK. RAN QRC QRH FOR SEVER (N881AS)
- [SDR HALA2022112800300](https://openairdocs.org/sdr/HALA2022112800300), Nov 25, 2022: Airbus A330243. FASTENER. LOOSE. ETOPS- ATB DUE TO ENG 2 EGT OVERTEMP MESSAGE ON ECAM. DURING PERFORMING TSM 77-21-00-810-855-A, FOUND LOOSE FASTENER ON  (N392HA)
- [SDR CALA2022112103193](https://openairdocs.org/sdr/CALA2022112103193), Nov 21, 2022: Airbus A319131. HARNESS. FAILED. ENG 2 EGT OVERTEMP ONT/O ROLL.TEMP APROX 890C 77-20-00-810-802-B. TOMC-MEREDITH UPDATED MAA CODE FIX USING VENDOR MAA SC (N831UA)
- [SDR GTIA2022101336720](https://openairdocs.org/sdr/GTIA2022101336720), Oct 11, 2022: Airbus A320232. NONE. NONE. "ON APPROACH OUT OF 8000' ENG 2 EGT OVERLIMIT ECAM RECEIVED ENG 2 EGT OBSERVED IN RED IN EXCESS OF 840*C. ENGINE GAS PAT (N637NK)
- [SDR SWIA202266598](https://openairdocs.org/sdr/SWIA202266598), Oct 9, 2022: Cndair CL6002B19. NONE. SHUTDOWN. IN CRUISE LEFT ITT IMMEDIATELY INCREASE 900+ FLASHING RED, LEFT ENGINE SPUTTERS, N1 DROPS TO ABOUT 30% AND STAYS. LEFT E (N693BR)
- [SDR YENA2022092300950](https://openairdocs.org/sdr/YENA2022092300950), Sep 20, 2022: Airbus A321231. SOLENOID VALVE. FAILED. FLT#70, FLL-BOS. ' ENG 1: EGT OVERTEMP ON START AUTO SHUTDOWN; PFR SHOWS ENG 1 FAIL/ENG 1 START FAULT. PER TSM TASK 73-0 (N971JT)
- [SDR NACA2022080200003](https://openairdocs.org/sdr/NACA2022080200003), Aug 2, 2022: Boeing 767323. HARNESS. SHORTED. WHILE PERFORMING EGT CHECK FOUND UPPER EGT HARNESS SHORTED TO GROUND. REMOVED AND REPLACED EGT UPPER HARNESS ON THE RIGH (N379CX)
- [SDR GTIA2022080136560](https://openairdocs.org/sdr/GTIA2022080136560), Jul 31, 2022: Airbus A321231. ENGINE. NONE. SHORT FINAL EGT 1 HIGH TEMP. PEAK AT 618' ECAM FOLLOWED INFLIGHT SHUTDOWN-REF L.P. 2898134-1 HIGH POWER ASSURANCE TEST P (N672NK)
- [SDR CALA2022070801675](https://openairdocs.org/sdr/CALA2022070801675), Jul 8, 2022: Boeing 767322. EGT INDICATION. WARNING MESSAGE. RT ENG HIGH EGT ON TAKE OFF. MAX EGT 737 SECONDS DURATION. DUE TO PREVIOUS HISTORY OF EGT FAULTS A POSITIVE FIX IS UNLOC (N649UA)
- [SDR NACA2022070600004](https://openairdocs.org/sdr/NACA2022070600004), Jul 6, 2022: Boeing 767323. NONE. NONE. DURING CRUISE ALTITUDE #2 ENG EGT SURGING BETWEEN 300 AND 800. ACCOMPLISHED FIM 77-21 FT 806. REMOVED AND REPLACED THERM (N379CX)
- [SDR YENA2022041800379](https://openairdocs.org/sdr/YENA2022041800379), Apr 17, 2022: Airbus A320232. EGT INDICATION. FALSE INDICATION. FLT#6116, SMF-LAX. ' AFTER ENG 1 START DURING ENG 2 START ENG 2 EGT CONTINUED TO CLIMB. AFTER 750 DEC C. ENG 1 EGT ECAM  (N712JB)
- [SDR HALA2022030400068](https://openairdocs.org/sdr/HALA2022030400068), Mar 3, 2022: Airbus A330243. NONE. NONE. AFTER LANDING #1 ENG SHOWED EGT OVERHEAT (PEGGED RED), IMMEDIATELY SHUT DOWN ENGINE, ALSO SHOWING ENG 1 MINOR FAULT. (RE (N390HA)
- [SDR GTIA2022013136250](https://openairdocs.org/sdr/GTIA2022013136250), Jan 30, 2022: Airbus A300*. NONE. NONE. REJECTED TAKEOFF DUE TO ENG 2 SENSOR FAULT-REMOVED AND REPLACED EGT HARNESS AND JUNCTION BOX IAW AMM 77-21-43, REMOVED A (N640NK)
- [SDR ABXA202212414](https://openairdocs.org/sdr/ABXA202212414), Jan 24, 2022: Boeing 767281. CABLE. BROKEN. DURING CLIMB PASSING 350, NOTICED LEFT EGT WAS LESS THAN 1/2 OF NORMAL. SEI SHOWED 40-46 REGARDLESS OF POWER SETTING.AIR (N767AX)
- [SDR YENA2021112200772](https://openairdocs.org/sdr/YENA2021112200772), Nov 21, 2021: Airbus A321231. EGT INDICATION. DAMAGED. FLT 1359, JFK-KIN (AIR TURN BACK TO JFK). AFTER TAKE-OFF ENG #2 EGT INDICATION WENT TO AMBER XXX'S WITH AN AMBER ARC. AI (N958JB)
- [SDR YV3R2020052900268](https://openairdocs.org/sdr/YV3R2020052900268), Apr 29, 2020: Robsin R44RAVENII. PROBE. INOPERATIVE. CUSTOMER REPORTED CYLINDER HEAD TEMPERATURE PROBE P/N: 3080-38 WAS INOPERATIVE.
- [SDR UIEA2019102865791](https://openairdocs.org/sdr/UIEA2019102865791), Oct 26, 2019: Boeing 76731K. IGNITER. FAILED. OVERTEMP ON #1 DURING RELIGHT, SHUTDOWN AT FL 400. RELIGHT AT FL 310. VIA QRH "IN FLIGHT". REF ITEM #1: CREW REPORTED TH (N1487A)
- [SDR EPUA201908087001](https://openairdocs.org/sdr/EPUA201908087001), Aug 7, 2019: Piper PA31350. PROBE. FALSE INDICATION. LEFT ENGINE CHT RED LINE IN CRUISE FLIGHT. REMOVED AND REPLACED LH ENGINE CHT PROBE IAW PA31 MM 77-20-03. OPS CHECK GOOD (N4301C)
- [SDR YV3R201906200120](https://openairdocs.org/sdr/YV3R201906200120), Jun 10, 2019: Robsin R44RAVENII. PROBE. ERRATIC. CUSTOMER REPORTED CYLINDER HEAD TEMPERATURE (CHT) INDICATION IS ERRATIC ABOVE IDLE SPEED. (N898GB)
- [SDR YV3R2019012200104](https://openairdocs.org/sdr/YV3R2019012200104), May 30, 2019: Robsin R44RAVENII. PROBE. INOPERATIVE. CUSTOMER REPORTED CYLINDER HEAD TEMPERATURE PROBE P/N: 3080-38 IS INOPERATIVE. (N144BB)
- [SDR YV3R2019012200102](https://openairdocs.org/sdr/YV3R2019012200102), May 30, 2019: Robsin R44RAVENII. PROBE. INOPERATIVE. CUSTOMER REPORTED CYLINDER HEAD TEMPERATURE PROBE P/N: 3080-38 DOS NOT READ (INDICATE).
- [SDR YV3R2019012200101](https://openairdocs.org/sdr/YV3R2019012200101), May 30, 2019: Robsin R44RAVENII. PROBE. INOPERATIVE. CUSTOMER REPORTED CYLINDER AHEAD TEMPERATURE PROBE P/N: 3080-38 IS INOPERATIVE. (N144BB)
- [SDR UIEA2016062700476](https://openairdocs.org/sdr/UIEA2016062700476), Jun 27, 2016: Boeing 76733AER. CABLE. LOOSE. NR 2 ENGINE LT AND RT SIDE 0300 AND 0900 O`CLOCK CORE AREA IN THE THERMOCOUPLE CABLE SLEEVE LOOSE CLOSE THE UNIT. THERMO (N648GT)
- [SDR BSYA2012019](https://openairdocs.org/sdr/BSYA2012019), May 14, 2012: Beech 58. PROBE. DEFECTIVE. AFTER TAKEOFF FROM BUF, PILOT NOTICED HIGH TEMPERATURES ON RIGHT ENGINE. PILOT RETURNED AND LANDED SAFELY AT BUF WITHOUT (N140S)
- [SDR BSYA2012017](https://openairdocs.org/sdr/BSYA2012017), Mar 27, 2012: Beech 58. PROBE. DEFECTIVE. SHORTLY AFTER TAKEOFF FROM TEB, PILOT NOTICED RIGHT ENGINE CYLINDER HEAD TEMP GAUGE SPIKED. PILOT RETURNED AND LANDED SA (N400RP)
- [SDR 2011F00190](https://openairdocs.org/sdr/2011F00190), Aug 23, 2011: Piper PA31350. PROBE. MALFUNCTIONED. CHT GAUGE IN COCKPIT PEGGED HIGH. ALL OTHER INDICATIONS NORMAL. ACFT RETURNED TO BASE. CHT PROBE FOUND TO HAVE AN OPEN C (N46FA)
- [SDR BSYA2011028](https://openairdocs.org/sdr/BSYA2011028), Aug 3, 2011: Piper PA31350. PROBE. FAILED. AFTER DEPARTING LCK TO GO TO FWA THE LEFT CHT INDICATION QUIT, THEN RETURNED TO LCK. MAINTENANCE REMOVED AND REPLACED CH (N106TG)
- [SDR CA110303001](https://openairdocs.org/sdr/CA110303001), Feb 28, 2011: Boeing 767375. SENSOR. FAILED. (CAN) DURING THE APPROACH TO R23 AT APPROX 170 KTS THE LT ENGINE SPOOLED DOWN. THE ENGINE DID NOT SHUT DOWN. WHEN POWER 
- [SDR BSYA2009036](https://openairdocs.org/sdr/BSYA2009036), Jun 18, 2009: Beech 58. PROBE. FAILED. AFTER TAKEOFF OUT OF DPA, THE LEFT CHT PEGGED OUT. RETURNED TO DPA. REMOVED AND REPLACED CHT PROBE, OPS CHECKS GOOD. (N1859K)
- [SDR CA081029002](https://openairdocs.org/sdr/CA081029002), Oct 27, 2008: Piper PA31. PROBE. MALFUNCTIONED. (CAN) PILOT OBSERVED LT ENG CYLINDER HEAD TEMP OVER RED-LINE. OTHER ENG PERIMETERS WERE NORMAL. PILOT CHOSE TO SHUTDOWN 
- [SDR BSY2008F00013](https://openairdocs.org/sdr/BSY2008F00013), Sep 26, 2008: Beech 58. PROBE. MALFUNCTIONED. LT CYLINDER HEAD TEMP, WENT ABOVE RED LINE ON TAKEOFF, PILOT THEN RETURNED TO DEPARTURE. REMOVED AND REPLACE CHT PROBE.  (N62500)
- [SDR 3611](https://openairdocs.org/sdr/3611), May 11, 2008: Cirrus SR22. PROBE. INOPERATIVE. AIRCRAFT DEPARTED KPGV TO KGMU WITH 2 PASSENGERS. DURING CRUISE, THE NR 6 CHT INDICATOR FAILED AND THE PILOT MADE AN UNS (N820CN)
- [SDR BSYA200700016](https://openairdocs.org/sdr/BSYA200700016), Dec 18, 2007: Beech 58. PROBE. DEFECTIVE. EN ROUTE FROM TEB TO HFD WHEN PILOT NOTICED HIGH CYL HEAD TEMP AND DIVERTED INTO MAINTENANCE BASE IN BDL. REMOVED AND RE (N3695V)
- [SDR 2350](https://openairdocs.org/sdr/2350), May 31, 2007: Cirrus SR22. PROBE. SHORTED. DURING CRUISE FLIGHT, THE NR 2 CHT READS 380*-420*. AIRCRAFT MADE AN UNSCHEDULED LANDING AT KCAE AT APPROXIMATELY 2010 L (N851CD)
- [SDR HEEA088645](https://openairdocs.org/sdr/HEEA088645), Jul 27, 2003: Aerosp AS355*. INDICATOR. DAMAGED. LT MOUNTING NUTS INSIDE INDICATOR SPIN WITH SCREWS. TO BE SENT TO VENDOR. (N854PH)
- [SDR HEEA077455](https://openairdocs.org/sdr/HEEA077455), Dec 3, 2001: Snias AS350B. INDICATOR. STUCK. T4 INDICATOR NEEDLE STICKS INTERMITTENTLY AT 700 DURING START. (N856PH)
- [SDR HEEA077451](https://openairdocs.org/sdr/HEEA077451), Dec 3, 2001: Snias AS350B. INDICATOR. DAMAGED. T4 INDICATOR WAS RECEIVED WITH RATTLE NOISE INSIDE. DID NOT INSTALL ON AIRCRAFT. WAS ISSUED AND RETIRED UNSERVICEABLE. S (N856PH)
- [SDR HEEA076629](https://openairdocs.org/sdr/HEEA076629), Oct 4, 2001: Snias AS350B. INDICATOR. WORN. ERRATIC INDICATIONS. SENT TO AMERICAN EUROCOPTER CORP. FOR CREDIT AGAINST REPLACEMENT PART PURCHASED. REFERENCE: RMA# R0 (N856PH)
- [SDR B2O2002F00010](https://openairdocs.org/sdr/B2O2002F00010), Aug 30, 2001: Doug C54BDC. THERMOCOUPLE. INOPERATIVE. CHT THERMOCOUPLE INOPERATIVE. CHANGED CHT THERMOCOUPLE. (N44911)
- [SDR CA010522019](https://openairdocs.org/sdr/CA010522019), May 8, 2001: Cessna 172. CYLINDER. SEPARATED. (CAN) NR 1 CYLINDER BARREL BROKE LEAVING CYLINDER BAS ATTACHED TO CRANKCASE AND CYLINDER ATACHED BY EXHAUST AND INTAKE. 
- [SDR CA010323006](https://openairdocs.org/sdr/CA010323006), Mar 7, 2001: Piper PA31350. EXHAUST VALVE. BROKEN. (CAN) PILOT REPORTED HIGH OIL TEMP VERNATHERN REPLACED AND ON GROUND RUN ENGINE RAN ROUGH. LARGE AMOUNT OF OIL NOTED COM
- [SDR CA010403012](https://openairdocs.org/sdr/CA010403012), Mar 5, 2001: Dhav DHC3. CYLINDER. CRACKED. (CAN) DURING A FLIGHT THE PILOT WAS FEELING AN ENGINE VIBRATION. HE REDUCED POWER AND CONTINUED HIS FLIGHT. ON MAINTENAN
- [SDR CA010313017](https://openairdocs.org/sdr/CA010313017), Feb 15, 2001: Beech 76. SPARK PLUG. DAMAGED. (CAN) IN CRUISE PILOT REPORT RT ENGINE SURGING, THEN COMPLETELY ROUGH RUNNING. ENGINE SHUTDOWN, AIRCRAFT LANDED SAFELY. 

All 62: https://openairdocs.org/jasc/7721/reports.md

## Other codes in chapter 77

- [JASC 7700](https://openairdocs.org/jasc/7700): Engine Indicating System (705 reports)
- [JASC 7710](https://openairdocs.org/jasc/7710): Power Indicating System (191 reports)
- [JASC 7711](https://openairdocs.org/jasc/7711): Engine Pressure Ratio (EPR) (456 reports)
- [JASC 7712](https://openairdocs.org/jasc/7712): Engine BMEP/Torque Indicating (1,239 reports)
- [JASC 7713](https://openairdocs.org/jasc/7713): Manifold Pressure (MP) Indicating (77 reports)
- [JASC 7714](https://openairdocs.org/jasc/7714): Engine RPM Indicating System (1,357 reports)
- [JASC 7720](https://openairdocs.org/jasc/7720): Engine Temperature Indicating System (695 reports)
- [JASC 7722](https://openairdocs.org/jasc/7722): Engine EGT/TIT Indicating System (1,198 reports)
- [JASC 7730](https://openairdocs.org/jasc/7730): Engine Ignition Analyzer System (52 reports)
- [JASC 7731](https://openairdocs.org/jasc/7731): Engine Ignition Analyzer (15 reports)
- [JASC 7732](https://openairdocs.org/jasc/7732): Engine Vibration Analyzer (237 reports)
- [JASC 7740](https://openairdocs.org/jasc/7740): Engine Integrated Instrument System (53 reports)
- [JASC 7797](https://openairdocs.org/jasc/7797): Engine Indicating System Wiring (592 reports)

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