# JASC 6310: Engine/Transmission Coupling - Type: JASC system/component code (FAA) - ATA chapter: 63 Main Rotor Drive - Title in the code table: ENGINE/TRANSMISSION COUPLING - Service difficulty reports: 772 - FAA code table: https://www.faa.gov/sites/faa.gov/files/JASC_Code.pdf#page=57 - Page: https://openairdocs.org/jasc/6310 ## What it covers The drive shaft between the engine and the main gearbox including the clutch and freewheel units (if applicable), and tilt rotor interconnect system. Typical parts are clutch, shaft, coupling, bearing, boot, seal, sync shaft, pulley, pulley bracket, belt, etc. ## Service difficulty reports (772, newest 50) - [SDR 8HBR20240509069](https://openairdocs.org/sdr/8HBR20240509069), Mar 27, 2025: Robsin R22BETA. BEARING. BRINELLED. BRINELLED SPINDLE BEARINGS DISCOVERED APPROX 99.3 HOURS SINCE NEW, FOUND DURING ROUTINE MAINTENANCE INSPECTION. (N917KF) - [SDR 2024FA0000554](https://openairdocs.org/sdr/2024FA0000554), Jul 28, 2024: Hughes 369E. CLUTCH. MAKING METAL. DURING A SCHEDULED 100 HOUR MAINTENANCE INSPECTION ON THE AIRCRAFT. THE MECHANIC QUESTIONED THE DARK BURNT APPEARANCE OF (N842JH) - [SDR EVCA09252023](https://openairdocs.org/sdr/EVCA09252023), Sep 21, 2023: Urocop EC130T2. SUPPORT. DAMAGED. PERFORMED TRANSMISSION SHAFT BEARING SUPPORT 10HR REOCCURRING AD 2022-01-05, DISCOVERED SHEARED RIVET AND CRACKS ON REAR (N202AH) - [SDR 2024FA0000205](https://openairdocs.org/sdr/2024FA0000205), Apr 21, 2023: Robsin R44RAVENII. CLUTCH ACTUATOR. BROKEN. AFTER PIC LANDED N31471 WITH THE COLLECTIVE FULL DOWN, THE CLUTCH LIGHT ILLUMINATED. AFTER LIGHT HAD BEEN ON FOR 10 SECO (N31471) - [SDR 2023FA0000214](https://openairdocs.org/sdr/2023FA0000214), Apr 13, 2023: Robsin R44. SHEAVE. UNKNOWN. BUMPS OR BUBBLES WERE FOUND IN THE UPPER SHEAVE GROOVES. THESE SEEM TO BE CORROSION POCKETS BETWEEN THE METALIZED PLATIN (N4377U) - [SDR 2022FA0000568](https://openairdocs.org/sdr/2022FA0000568), Oct 3, 2022: Hughes 369E. SPRAG CLUTCH. BROKEN. INITIAL CLUTCH WAS REMOVED FOR A DIFFERENT DISCREPANCY AND WAS FOUND TO HAVE A BAD SPRAG CLUTCH 300 HOURS AFTER OVERHAUL (N774CB) - [SDR CHIA5149](https://openairdocs.org/sdr/CHIA5149), Jul 19, 2022: Boeing 234. TRANSMISSION. OVERTEMP. WE JUST COMPLETED ABOUT 2 HOURS ON A FIRE FIGHTING MISSION 15NM WEST OF BECIN FOREST SERVICE BASE AND WERE RETURNING TO (N242CH) - [SDR 2022F00242](https://openairdocs.org/sdr/2022F00242), May 18, 2022: Bell 206B3. FREEWHEEL UNIT. FAILED. THE FREEWHEELING UNIT WAS FAILING CAUSING THE MAIN GEARBOX CHIP LIGHT TO INTERMITTENTLY ILLUMINATE. WHEN THE CHIP DETECT (N910BR) - [SDR JYDR20220120016](https://openairdocs.org/sdr/JYDR20220120016), Jan 19, 2022: Skrsky S64E. NONE. BROKEN. WHILE LANDING FROM A HOVER, AS THE WHEELS TOUCHED DOWN A VIBRATION WAS FELT. PILOTS PULLED EACH ENGINE BACK SEPARATELY A - [SDR QMLA2021052420025](https://openairdocs.org/sdr/QMLA2021052420025), May 20, 2021: Bell 407. TRANSMISSION. RATCHETING. ON TAKEOFF PILOT HEARD A VERY LOUD "BANG" INSIDE THE CABIN. PILOT LOWERED POWER AND SET THE AIRCRAFT BACK DOWN WHERE IT (N407VV) - [SDR JYDR20201013282](https://openairdocs.org/sdr/JYDR20201013282), Oct 13, 2020: Skrsky S64F. ATTACH BOLT. BROKEN. PILOTS SUDDENLY FELT A VIBRATION AND HEARD A HOWLING NOISE. THEY RETURNED TO THE LANDING SITE AND SHUT DOWN. AT INSPECTI (N159AC) - [SDR N3XR20200827001](https://openairdocs.org/sdr/N3XR20200827001), Aug 19, 2020: Diamon DA42NG. GEARBOX. CONTAMINATED. DURING A ROUTINE INSPECTION, THE GEAR BOX MAGNETIC PLUG CONTAINED LARGE PIECES OF METAL. THE GEAR BOX WAS REPLACED WITH (N315ER) - [SDR N3XR20200827002](https://openairdocs.org/sdr/N3XR20200827002), Aug 4, 2020: Diamon DA42NG. GEARBOX. MAKING METAL. DURING A ROUTINE INSPECTION, SEVERAL LARGE PARTICLES WERE FOUND ON THE GEARBOX MAGNETIC DRAIN PLUG. THE GEARBOX WAS REPL (N304ER) - [SDR 2020FA0000319](https://openairdocs.org/sdr/2020FA0000319), Jun 22, 2020: Robsin R44RAVENII. SPRAG CLUTCH. ABNORMAL. OWNER COMPLAINED OF POWER LOSS DURING LEVEL OFF AND FLARE AFTER DESCENT. HE INSISTED THERE WAS NO "NEEDLE SPLIT". IN SPI (N441CD) - [SDR N3XR20200827003](https://openairdocs.org/sdr/N3XR20200827003), Jun 19, 2020: Diamon DA42NG. GEARBOX. MAKING METAL. DURINE A ROUTINE INSPECTION, LARGE PIECES OF METAL WERE FOUND ON THE ENGINE GEAR BOX MAGNETIC PLUG. THE GEARBOX WAS REPL (N309ER) - [SDR YV3R2019021300022](https://openairdocs.org/sdr/YV3R2019021300022), Feb 11, 2019: Robsin R22BETA. CLUTCH ACTUATOR. MALFUNCTIONED. CUSTOMER REPORTED CLUTCH ACTUATOR MOTOR IS SURGING AND RUNNING VERY SLOW. (N114VG) - [SDR 2AFA20170719001](https://openairdocs.org/sdr/2AFA20170719001), Jul 19, 2017: Robsin R44RAVENII. CLUTCH ACTUATOR. CRACKED. FAILURE OF ACTUATOR ASSEMBLY. THE BRACKETS DISCONNECTING THAT CAUSED THE UPPER BREAK.” MR. WEBSTER ALSO STATED THIS WAS (N188DD) - [SDR EVGR201611080001](https://openairdocs.org/sdr/EVGR201611080001), Oct 13, 2016: Robsin R44RAVENII. SPRAG ASSY. MAKING METAL. DURING THE 100 HOUR INSPECTION, THE CLUTCH LUBRICATION INSPECTION WAS PERFORMED PER ROBINSON MM 7.210. WHEN THE OIL WAS (N622) - [SDR H44R2016051300001](https://openairdocs.org/sdr/H44R2016051300001), May 11, 2016: Hughes 369FF. COVER PLATE. WORN. DURING REPLACEMENT OF THE OVER RUNNING CLUTCH, A SPECIAL TOOL IS REQUIRED TO TORQUE THE INTERNAL WRENCHED RETENTION NUT (N532EZ) - [SDR CA151021003](https://openairdocs.org/sdr/CA151021003), Oct 21, 2015: Robsin R44. SPRAG CLUTCH. CRACKED. (CAN) FOUND CRACKED SPRAG CLUTCH DURING DISASSEMBLY. - [SDR CA150813007](https://openairdocs.org/sdr/CA150813007), Jul 31, 2015: Bell 212. BOOT. TORN. (CAN) ON A POST FLIGHT INSPECTION IT WAS NOTED THE FWD COUPLING BOOT, M/R TRANSMISSION END, HAD SOME SLIGHT GREASE LEAKA - [SDR CA150813003](https://openairdocs.org/sdr/CA150813003), Jul 22, 2015: Snias AS350B2. FLEX COUPLING. CRACKED. (CAN) DURING SHUTDOWN, ROTORS TURNING LOUD CLICKING HEARD FROM COUPLING WHILE ROTORS WERE SLOWING DOWN. COUPLING FOUND C - [SDR CA150813004](https://openairdocs.org/sdr/CA150813004), Jul 11, 2015: Bell 412. BOOT. DISINTEGRATED. (CAN) ACFT HAD A HARD LANDING AFTER A MAIN DRIVESHAFT COUPLING FAILURE. DURING THE INVESTIGATION IT WAS NOTED THERE WAS - [SDR CA141212009](https://openairdocs.org/sdr/CA141212009), Dec 10, 2014: Bell 206B. CLUTCH. WORN. (CAN) DURING TRAINING, IT WAS NOTICED THAT THE TACH NEEDLES DID NOT SEPARATE WHEN THE THROTTLE WAS ROLLED BACK TO IDLE. - [SDR CA141103026](https://openairdocs.org/sdr/CA141103026), Nov 1, 2014: Robsin R44RAVENII. JACKSCREW. DAMAGED. (CAN) UPON START UP IN THE FIELD AT A REMOTE SITE, THE PILOT FIRED THE ENGINE AS NORMAL AND ENGAGED THE CLUTCH, AS HE WA - [SDR CA141103033](https://openairdocs.org/sdr/CA141103033), Oct 11, 2014: Robsin R44RAVENII. JACKSCREW. DAMAGED. (CAN) DURING STARTING PROCEDURE, IN A REMOTE SITE, THE PILOT FIRED THE ENGINE AS NORMAL, ENGAGED THE CLUTCH AND WAS WAIT - [SDR 2014FA0000435](https://openairdocs.org/sdr/2014FA0000435), Jun 21, 2014: Amtr EXEC162F. BELT. FAILED. AT APPROXIMATELY 300 FEET ALTITUDE, PILOT HEARD A LOUD BANG AND EXPERIENCED AN IMMEDIATE LOSS OF POWER. ATTEMPTED EMERGE (N6828D) - [SDR CA140328008](https://openairdocs.org/sdr/CA140328008), Mar 28, 2014: Bell 407. HOUSING. CRACKED. (CAN) DURING OVERHAUL THE FREEWHEEL ASSEMBLY, IT WAS NOTICED THAT A LARGE CRACK HAD FORMED UNDER THE O-RING GROOVE OF TH - [SDR CA140217004](https://openairdocs.org/sdr/CA140217004), Jan 26, 2014: Hughes 369D. O-RING. MISSING. (CAN) THE OVER RUNNING CLUTCH WAS PURCHASED AS AN EXCHANGE UNIT. THIS UNIT WAS INSTALLED AT TTAF 16552.9 HRS. THE INSPEC - [SDR QMLA2014012214010](https://openairdocs.org/sdr/QMLA2014012214010), Jan 22, 2014: Doug MD900. TRANSMISSION. MAKING METAL. MULTIPLE MAIN TRANSMISSION CHIP LIGHTS, AFTER FOLLOWING CSP 900RMM 2 CHAPTER 63-20-00 & TABLE 601. CHIPS INDICATED ALL U (N902LC) - [SDR CA130812004](https://openairdocs.org/sdr/CA130812004), Aug 2, 2013: Robsin R44RAVENII. SPRAG CLUTCH. FAILED. (CAN) "SUDDEN YAW, GRINDING NOISE AND CLUTCH WARNING LIGHT IN STRAIGHT AN LEVEL FLIGHT, ALL WITHIN LESS THAN A SECOND. L - [SDR CA130731006](https://openairdocs.org/sdr/CA130731006), Jul 31, 2013: Bell 206B. SHAFT. CORRODED. (CAN) CORROSION WHERE THE FRONT SEAL RUNS ON OUTER DIAMETER OF THE INNER SHAFT. - [SDR CA130617012](https://openairdocs.org/sdr/CA130617012), Jun 16, 2013: Robsin R44RAVENII. ACTUATOR. WORN. (CAN) DURING ACFT INSPECTION MOVEMENT WAS NOTED BETWEEN THE CLUTCH ACTUATOR GEARBOX HSG AND SHAFT. - [SDR CA130521019](https://openairdocs.org/sdr/CA130521019), May 17, 2013: Bell 206B. FREEWHEEL UNIT. BLOCKED. (CAN) THE REPORTED HE FELT THE ACFT TWITCH, AND YAW, FOLLOWED BY THE NEEDLES ON THE GAUGES FLUCTUATING, GIVING INDICATIO - [SDR CA121130005](https://openairdocs.org/sdr/CA121130005), Nov 28, 2012: Robsin R44RAVENII. WIRE. LOOSE. (CAN) PILOT REPORTED INTERMITTENT CLUTCH ACTUATOR WARNING. CLUTCH ACTUATOR REPLACED. CLUTCH ACTUATOR WAS FOUND TO HAVE A - [SDR CA121031007](https://openairdocs.org/sdr/CA121031007), Oct 28, 2012: Robsin R44RAVENII. SEAL. LEAKING. (CAN) DURING INSPECTION OF THE ACFT OIL, WAS NOTED LEAKING FROM THE REAR SEAL OF THE CLUTCH ASSEMBLY. SEAL HAD DISLODGED - [SDR CA121011011](https://openairdocs.org/sdr/CA121011011), Oct 10, 2012: Hughes 369D. SPRAG CLUTCH. DAMAGED. (CAN) DURING THE 100 HOUR INSPECTION, THE ENGINEER NOTICED THAT THE OIL IN THE CLUTCH WAS VERY DARK. HE REMOVED THE ASSY - [SDR CA121012003](https://openairdocs.org/sdr/CA121012003), Sep 30, 2012: Robsin R44RAVENII. ACTUATOR. FAILED. (CAN) ACFT WOULD NOT START. FOUND CLUTCH ACTUATOR SWITCH HAD FAILED. CLUTCH ACTUATOR REPLACED. - [SDR CA120928004](https://openairdocs.org/sdr/CA120928004), Sep 27, 2012: Robsin R44. ACTUATOR. FAILED. (CAN) ON SHUTDOWN ELECTRIC CLUTCH ACTUATOR SWITCHED TO THE DISENGAGED POSITION BUT DID NOT RESPOND. DOWN LIMIT SWITCH TE - [SDR CA120813028](https://openairdocs.org/sdr/CA120813028), Aug 5, 2012: Robsin R44RAVENII. ACTUATOR. UNSERVICEABLE. (CAN) CLUTCH ACTUATOR SWITCH NOT WORKING. CLUTCH ACTUATOR ASSY REPLACED. - [SDR ALGA2012071302](https://openairdocs.org/sdr/ALGA2012071302), Jul 13, 2012: Bell 407. ADAPTER. CORRODED. DURING COMPLIANCE WITH 3000 HR O/H OF THE F/W UNIT ASSY, THE ADAPTER WAS DISCARDED DUE TO PITTING AND CORROSION BEYOND M (N667AL) - [SDR CA121015003](https://openairdocs.org/sdr/CA121015003), Jul 2, 2012: Robsin R22BETA. SPRAG CLUTCH. CRACKED. (CAN) CLUTCH ASSEMBLY FOUND NOISY DURING OPERATION. UPON DISASSEMBLY FOUND SPRAG ASSEMBLY CRACKED IN MULTIPLE PLACES. - [SDR CA120618010](https://openairdocs.org/sdr/CA120618010), Jun 12, 2012: Robsin R44RAVENII. ACTUATOR. INTERMITTENT. (CAN) CLUTCH ACTUATOR INTERMITTENT. CLUTCH ACTUATOR REPLACED. - [SDR CA120612011](https://openairdocs.org/sdr/CA120612011), May 28, 2012: Robsin R44. ACTUATOR. INTERMITTENT. (CAN) INTERMITTENT CLUTCH WARNING LIGHT IN FLIGHT. CLUTCH ACTUATOR REPLACED. - [SDR ALGA2012051803](https://openairdocs.org/sdr/ALGA2012051803), May 18, 2012: Bell 407. ADAPTER. CORRODED. ADAPTER CORRODED BEYOND LIMITS. (N607AL) - [SDR ALGA2012051802](https://openairdocs.org/sdr/ALGA2012051802), May 18, 2012: Bell 407. ADAPTER. CORRODED. ADAPTER CORRODED BEYOND LIMITS. (N607AL) - [SDR ALGA201204171201](https://openairdocs.org/sdr/ALGA201204171201), Apr 16, 2012: Bell 206L4. ADAPTER. CORRODED. FREE WHEEL UNIT ADAPTER CORRODED BEYOND LIMITS. (N272AL) - [SDR ALGA201203121206](https://openairdocs.org/sdr/ALGA201203121206), Mar 12, 2012: Bell 206L4. ADAPTER. CORRODED. FREE WHEEL UNIT ADAPTER HAS PITTING CORROSION BEYOND LIMITS. (N189AL) - [SDR ALGA201203121205](https://openairdocs.org/sdr/ALGA201203121205), Mar 12, 2012: Bell 206L4. HOUSING. CORRODED. FREE WHEEL UNIT HOUSING HAS PITTING CORROSION BEYOND LIMITS. (N189AL) - [SDR CA120228019](https://openairdocs.org/sdr/CA120228019), Feb 27, 2012: Skrsky S92A. BEARING. DAMAGED. (CAN) INPUT MODULE WAS REMOVED FROM ACFT DUE TO A RIVET HEAD FOUND ON THE INPUT MODULE CHIP DETECTOR. FINDINGS DURING DI All 772: https://openairdocs.org/jasc/6310/reports.md ## Other codes in chapter 63 - [JASC 6300](https://openairdocs.org/jasc/6300): Main Rotor Drive System (637 reports) - [JASC 6320](https://openairdocs.org/jasc/6320): Main Rotor Gearbox (1,930 reports) - [JASC 6321](https://openairdocs.org/jasc/6321): Main Rotor Brake (275 reports) - [JASC 6322](https://openairdocs.org/jasc/6322): Rotorcraft Cooling Fan System (213 reports) - [JASC 6330](https://openairdocs.org/jasc/6330): Main Rotor Transmission Mount (603 reports) - [JASC 6340](https://openairdocs.org/jasc/6340): Rotor Drive Indicating System (265 reports) - [JASC 6397](https://openairdocs.org/jasc/6397): Main Rotor Drive System Wiring (17 reports) --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.