# JASC 6420: Tail Rotor Head - Type: JASC system/component code (FAA) - ATA chapter: 64 Tail Rotor - Title in the code table: TAIL ROTOR HEAD - Service difficulty reports: 907 - FAA code table: https://www.faa.gov/sites/faa.gov/files/JASC_Code.pdf#page=58 - Page: https://openairdocs.org/jasc/6420 ## What it covers The rotating assembly which supports the tail rotor blades. Does not include the controlling aspects which are filed in JASC code 6720. Typical parts are trunnion, fairing, damper plate, shaft, hub, etc. ## Service difficulty reports (907, newest 50) - [SDR QR9R2026040600002](https://openairdocs.org/sdr/QR9R2026040600002), Apr 6, 2026: Bolkms BK117C2. ROTOR HEAD. OUT OF LIMITS. THE LAMINATED PILE ASSEMBLY WAS RECEIVED FROM SUPPLY WITH A GAP EXCESS OF .0078". - [SDR 8LFA202603100002](https://openairdocs.org/sdr/8LFA202603100002), Mar 10, 2026: Bell 407. NUT. LOOSE. DURING FLIGHT IT WAS NOTED AN ABNORMAL METALLIC NOISE EMANATING FROM THE TAIL BOOM AREA. IT WAS DECIDED TO PERFORM A PRE (N463LF) - [SDR QR9R2026021800001](https://openairdocs.org/sdr/QR9R2026021800001), Feb 18, 2026: Bolkms BK117C2. ROTOR HEAD. OUT OF LIMITS. RECEIVED LAMINATED PILE ASSEMBLY FROM SUPPLY WITH .013'' GAP IN LAMINATED PILE. MAX IS .008''. - [SDR QR9R2025040200001](https://openairdocs.org/sdr/QR9R2025040200001), Apr 2, 2025: Bolkms BK117C2. BEARING. FRAYED. BEARING SLEEVE ASSY TEFLON LINER WAS FOUND TO BE WORN (FRAYED) BEYOND LIMITS. PART WAS RECEIVED NEW FROM SUPPLY. REPLACE - [SDR QMLA2025021020015](https://openairdocs.org/sdr/QMLA2025021020015), Feb 10, 2025: Urocop EC135P1. COTTER PIN. MISSING. YAW SERVO ACTUATOR BRACE HAD A MISSING COTTER PIN ON POST FLIGHT INSPECTION. VERIFIED TORQUE ON T/R NUT. INSTALLED COTTE (N102HN) - [SDR QR9R2024050700001](https://openairdocs.org/sdr/QR9R2024050700001), May 7, 2024: Bolkms BK117C2. UNKNOWN. MISALIGNED. DURING INSTALLATION OF THE LAMINATED PILE ASSEMBLY, THE REPAIRED CENTER BORE DID NOT ALLOW PROPER ALIGNMENT OF THE THROU - [SDR 2023F00311](https://openairdocs.org/sdr/2023F00311), Oct 18, 2023: Bolkms BK117C2. SPHERICAL BEARIN. WORN. ON DEPARTURE AND CLIMB OUT, THE PILOT NOTICED A VIBRATION IN THE T/R PEDALS THAT WOULD INCREASE WITH POWER WAS INCREASES (N452MH) - [SDR QR9R2022112200002](https://openairdocs.org/sdr/QR9R2022112200002), Nov 22, 2022: Bolkms BK117C2. SLEEVE. OUT OF LIMITS. INNER SLEEVE ASSY WAS RECEIVED FROM SUPPLY WITH REPLACEMENT BUSHINGS IMPROPERLY HONED WHICH PREVENTS BOLT FROM PASSING T - [SDR QR9R2022111500001](https://openairdocs.org/sdr/QR9R2022111500001), Nov 15, 2022: Bolkms BK117C2. BOLT. OUT OF TOLERANCE. FITTED BOLT WAS RECEIVED FROM SUPPLY OUT OF TOLERANCE. MINIMUM LIMIT FOR OUTSIDE DIAMETER IS 0.038" IAW AMM 64-20-00, 6- - [SDR 2022F00337](https://openairdocs.org/sdr/2022F00337), Aug 29, 2022: Agusta AW139. DAMPER. DEPARTED. ON A NORMAL APPROACH TO THE H AT THE NORTH RAMP, AT ABOUT 150 AGL, WE SUDDENLY FELT A STRONG VIBRATION. WE PROCEEDED TO (N152PH) - [SDR QR9R20220609002](https://openairdocs.org/sdr/QR9R20220609002), Jun 9, 2022: Bolkms BK117C2. SLEEVE. GOUGED. AFTER RECEIVING PART FROM AIRBUS, MAINTENANCE DETECTED THE INNER SLEEVE ASSY WAS GOUGED BEYOND LIMITS. - [SDR QR9R20220405001](https://openairdocs.org/sdr/QR9R20220405001), Apr 5, 2022: Bolkms BK117C2. BALLAST. DAMAGED. WHILE PERFORMING MAINTENANCE TO REPLACE T/R WEIGHTS, T/R WEIGHT STOPPED HALFWAY ON THE FORK WHILE BEING THREADED. INTERN - [SDR EVCA20210623002](https://openairdocs.org/sdr/EVCA20210623002), Jun 21, 2021: Bell 206L1. SUPPORT FITTING. SEIZED. ON THE P/N 206-033-426-001 SUPPORT FITTING ASSY., THE MOUNTING EARS WHICH PROVIDES THE PIVOT POINT FOR T/R CONTROL BELLC (N239AE) - [SDR QR9R20210611001](https://openairdocs.org/sdr/QR9R20210611001), Jun 11, 2021: Bolkms BK117C2. BEARING. OUT OF TOLERANCE. SYSTEMIC AND PREMATURE FAILURE OF THE T/R HEAD SPHERICAL BEARINGS RESULTING IN EXCESSIVE RADIAL PLAY AND TAIL ROTOR VIBR - [SDR 2020F00359](https://openairdocs.org/sdr/2020F00359), Aug 13, 2020: Bell 206L1. BEARING. WORN. DURING TAIL ROTOR BALANCE, FEATHER BEARINGS WERE FOUND WORN. BLADES WERE SENT BACK TO MANUFACTURER FOR BEARING REPLACEME - [SDR X2RL2020061800001](https://openairdocs.org/sdr/X2RL2020061800001), Jun 18, 2020: Hughes 369D. BEARING. SEIZED. PILOT COMPLAINED OF STICKY T/R PEDAL MOVEMENT, FOUND T/R SWASHPLATE PIVOT BEARING SEIZED. REMOVED T/R SWASHPLATE AND SEN (N717MA) - [SDR YV3R2020050900258](https://openairdocs.org/sdr/YV3R2020050900258), Apr 28, 2020: Robsin R44. ELASTOMER. DEFECTIVE. CUSTOMER REPORTED BEARING, ELASTOMER P/N: B361-2 HAD A CRACK IN THE RUBBER BETWEEN ELASTOMER AND CASE. - [SDR 2019FA0000414](https://openairdocs.org/sdr/2019FA0000414), Nov 20, 2019: Agusta AW109SP. TRUNNION. SCORED. PILOT REPORTED A MAIN ROTOR VIBRATION. UPON TRACK AND BALANCE OF THE MAIN ROTOR IT WAS DISCOVERED THAT THE VIBRATION WAS (N291HC) - [SDR YV3R2019101220198](https://openairdocs.org/sdr/YV3R2019101220198), Oct 3, 2019: Robsin R44. BEARING. FAILED. CUSTOMER REPORTED TAIL ROTOR PITCH CONTROL P/N: C031-1 HAS ROUGH BEARINGS. - [SDR CA190319022](https://openairdocs.org/sdr/CA190319022), Mar 18, 2019: Bell 429. HUB. MALFUNCTIONED. (CAN) PRIOR TO DELIVERY TO CUSTOMER, THE PILOT NOTICED THE COUPLING TEETH WERE NOT ENGAGED WITH THE YOKE. SHIP HAD FLEW - [SDR CA190304021](https://openairdocs.org/sdr/CA190304021), Feb 26, 2019: Bell 429. NUT. LOOSE. (CAN) DURING PRE-FLIGHT CHECK THE TAILROTOR MAST NUT WAS FOUND LOOSE. AS EVERY MORNING A LICENSED MECHANIC CARRIED OUT T - [SDR CA190222008](https://openairdocs.org/sdr/CA190222008), Feb 18, 2019: Bell 429. HUB. DAMAGED. (CAN) IT WAS REPORTED BY BELL: (FLIGHT SAFETY REPORT). AIRCRAFT COMES IN FOR RECONFIGURATION. AT DAILY INSPECTION, EXCES - [SDR 2018FA0000433](https://openairdocs.org/sdr/2018FA0000433), Sep 10, 2018: Agusta AW109SP. BUSHING. LOOSE. DURING A WALK AROUND INSPECTION THE TECHNICIAN NOTICED THAT THE ROCKER ARM ASSEMBLY ON THE TAIL ROTOR HUB ASSEMBLY WAS V (N45BZ) - [SDR 2018FA0000357](https://openairdocs.org/sdr/2018FA0000357), Sep 7, 2018: Hynes B2A. HUB. CRACKED. INVESTIGATION REVEALED THE TAIL ROTOR AND UPPER TAIL ROTOR GEARBOX ASSEMBLY TO BE MISSING FROM THE PRIMARY ACCIDENT SITE (N5901X) - [SDR MKHR2018091300000](https://openairdocs.org/sdr/MKHR2018091300000), Aug 8, 2018: Hughes 369D. BOLT. SHEARED. DURING CRUISE FLIGHT THE PILOT EXPERIENCED AN EXCESSIVE TAIL ROTOR VIBRATION. THE PILOT THEN EXECUTED A PRECAUTIONARY LA (N369MH) - [SDR JYDR20170324074](https://openairdocs.org/sdr/JYDR20170324074), Mar 22, 2017: Skrsky S64E. BRACKET. MISSING. WHILE CONDUCTING A TAIL ROTOR BALANCE SESSION, BALANCE CHANGED. VISUAL INSPECTION OF THE TAIL ROTOR HEAD SHOWED AN VERNI - [SDR 2A6R2016022201](https://openairdocs.org/sdr/2A6R2016022201), Feb 22, 2016: Bell 429. BEARING. SHEARED. TAIL ROTOR HUB ASSY, PN: 429-012-101-117, SN: ZC21 WAS REMOVED DUE TO INBD BEARING, PN: 429-3112-103-113 BECAME DELAMINA (N911ED) - [SDR 2A6R2016FA0000093](https://openairdocs.org/sdr/2A6R2016FA0000093), Feb 22, 2016: Bell 429. BEARING. DAMAGED. TAIL ROTOR HUB ASSY, PN: 429-012-101-115, SN: ZC19 WAS REMOVED DUE TO INBD BEARING, PN: 429-3112-103-115 BECAME DELAMINA (N911NM) - [SDR CA160119009](https://openairdocs.org/sdr/CA160119009), Oct 15, 2015: Bell 206L3. ROTOR. SEPARATED. (CAN) ACFT WAS ON AN AERIAL APPLICATION MISSION WHEN IT WAS REQUIRED TO MAKE A FORCED LANDING. INITIAL REPORTS STATE THE - [SDR CA150922013](https://openairdocs.org/sdr/CA150922013), Sep 22, 2015: Bell 212. BEARING. DAMAGED. (CAN) DURING THE OVERHAUL OF A TAIL ROTOR ASSY THE NEEDLE BEARING ON THE CONTROL LEVER WAS FOUND TO BE DAMAGED DURING IN - [SDR CA150501002](https://openairdocs.org/sdr/CA150501002), Apr 28, 2015: Bell 429. BEARING. WORN. (CAN) DURING ROUTINE INSPECTION, EXCESS PLAY OBSERVED IN TAIL ROTOR PITCH LINK. ATTACHED VIDEO SHOWS THE PRESENT CONDITI - [SDR CA150327013](https://openairdocs.org/sdr/CA150327013), Mar 24, 2015: Bell 206B. NUT. CRACKED. (CAN) DURING A SCHEDULED TAIL ROTOR REMOVAL AME WENT TO REMOVE THE TAIL ROTOR CROSSHEAD, 206-011-857-001. RETAINING NUT - [SDR CA150204012](https://openairdocs.org/sdr/CA150204012), Jan 27, 2015: Bell 429. BEARING. DISLODGED. (CAN) DURING PREFLIGHT, PILOT NOTICED BEARING DISLODGED FROM LINK. PILOT STATES THE LINK WAS NOT LIKE THAT THE PREVIOUS - [SDR CA150127002](https://openairdocs.org/sdr/CA150127002), Jan 22, 2015: Bell 429. BEARING. WORN. (CAN) T/R P/C LINK BEARING, LINK, AND BEARING FAILURE OF A 429 T/R P/C LINK BEARING, LINK PN 429-012-112-101, BEARING, P - [SDR 2014FA0000669](https://openairdocs.org/sdr/2014FA0000669), Nov 14, 2014: Bell 206A. NUT. CORRODED. CORROSION EXCESSIVE IN THE MAST BEARING RETAINING NUT AREA. AREA J IN THE MFG CR&O MANUAL. - [SDR 2A6R201411201572](https://openairdocs.org/sdr/2A6R201411201572), Nov 14, 2014: Bell 429. ELASTOMER. FAILED. TR FLAPPING BEARING ELASTOMER FAILURE & DELAMINATION AT 1054.25 HOURS. SLL IS 15,000 HOURS. (N911KX) - [SDR CA141023007](https://openairdocs.org/sdr/CA141023007), Oct 6, 2014: Hughes 269C1. BEARING. MAKING METAL. (CAN) THE ROTOR SYS WAS FOUND TO BE INCREASING IN VIBRATION. CHECKED THROUGH THE SYSTEM AND FOUND THE BEARINGS WHEN PURG - [SDR CA140908028](https://openairdocs.org/sdr/CA140908028), Sep 4, 2014: Bell 412EP. YOKE. UNSERVICEABLE. (CAN) DURING THE DAILY INSPECTION IT WAS NOTICED THAT 1 TAIL ROTOR YOKE FEATHERING BEARING OUTER RACE STAKE HAD FAILED. - [SDR CA140626002](https://openairdocs.org/sdr/CA140626002), Jun 25, 2014: Snias AS350BA. SHAFT. WORN. (CAN) WHEN THE TAIL ROTOR WAS ROTATED CLOCKWISE OR COUNTER CLOCKWISE, A NOISE WAS DETECTED. AFTER INVESTIGATION, IT WAS - [SDR 3GMA2014052801](https://openairdocs.org/sdr/3GMA2014052801), May 16, 2014: Bolkms BK117C2. BEARING. UNSTAKED. ON A PREFLIGHT INSPECTION, FOUND BEARING OF TAIL ROTOR PITCH LINK UNSTAKED & LOOSE IN PITCH LINK. (N482LF) - [SDR CA140325006](https://openairdocs.org/sdr/CA140325006), Mar 24, 2014: Bell 206L4. BEARING. MISINSTALLED. (CAN) THE FEATHERING BEARING WAS STAKED FAR TOO TIGHT. CAUSING RESTRICTION ON TAIL ROTOR CONTROL. THIS WAS NOTED ON A PR - [SDR CA140127001](https://openairdocs.org/sdr/CA140127001), Jan 24, 2014: Bell 206L4. BOLT. SHEARED. (CAN) IN FLIGHT PILOT COULD FEEL VIBRATION IN THE AIRFRAME, DECIDED TO LAND. ENGINEER INSPECTED AIRFRAME INCLUDING REMOV - [SDR CA140109003](https://openairdocs.org/sdr/CA140109003), Dec 18, 2013: Bell 206L4. PLUG. LEAKING. (CAN) ACFT HAD JUST DEPARTED FROM AN OFFSHORE PLATFORM WHEN THE T/R PEDALS LOCKED UP AT APPROXIMATELY MID-TRAVEL. PILOT - [SDR CA131118028](https://openairdocs.org/sdr/CA131118028), Nov 18, 2013: Agusta AW139. SLIP RING. FAILED. (CAN) DURING A 50HR BY-WEEKLY INSPECTION, ENGINEER DISCOVERED THAT THE DUPLEX BEARING IN THE TAIL ROTOR SLIP RING HAD DE - [SDR CA131107007](https://openairdocs.org/sdr/CA131107007), Nov 7, 2013: Snias AS350BA. ROD. CRACKED. (CAN) DURING A VISUAL INSPECTION, A CRACK WAS FOUND AT THE AFT END OF THE TAIL ROTOR ACTUATING ROD, WHERE THE BEARING IS - [SDR CA131114002](https://openairdocs.org/sdr/CA131114002), Oct 24, 2013: Bell 206B. PITCH HORN. DAMAGED. (CAN) RAISED CENTER LUG OF PITCH HORN FOULING ON YOKE. BOLT HOLES FOR HORN ATTACHMENT AND WASHER WEIGHTS MIS-LOCATED APP - [SDR CA131002009](https://openairdocs.org/sdr/CA131002009), Oct 1, 2013: Agusta AW139. SLIP RING. FAILED. (CAN) DURING A POST FLIGHT WALK AROUND, FROM A 1 HR FLT, IT WAS NOTED THE FIPS WIRING ON THE TAIL ROTOR WAS DAMAGED. INS - [SDR CA130820004](https://openairdocs.org/sdr/CA130820004), Aug 15, 2013: Bell 204B. BOLT. SHEARED. (CAN) DURING CRUISE FLIGHT, THE ACFT DEVELOPED A SUDDEN AND SEVERE VIBRATION. THE PILOT IMMEDIATELY LANDED AND SHUTDOWN. - [SDR CA130809008](https://openairdocs.org/sdr/CA130809008), Aug 8, 2013: Snias AS350B2. BEARING. WORN. (CAN) FOUND TAIL ROTOR HALF MOON BEARINGS WEARING QUICKLY OVER SEVERAL DAILY INSPECTIONS IN AREAS REFERENCED IN DOCUMENT - [SDR CA130813005](https://openairdocs.org/sdr/CA130813005), Aug 2, 2013: Snias AS350B2. BEARING. CRACKED. (CAN) TAIL ROTOR HALF SHELL BEARINGS CONSIST OF 4 SEPARATE BEARINGS TO MAKE 1 SET. 2 OF THE 4 BEARINGS WERE FOUND WITH C All 907: https://openairdocs.org/jasc/6420/reports.md ## Other codes in chapter 64 - [JASC 6400](https://openairdocs.org/jasc/6400): Tail Rotor System (95 reports) - [JASC 6410](https://openairdocs.org/jasc/6410): Tail Rotor Blades (1,148 reports) - [JASC 6440](https://openairdocs.org/jasc/6440): Tail Rotor Indicating System (4 reports) - [JASC 6497](https://openairdocs.org/jasc/6497): Tail Rotor System Wiring (3 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.