# Service difficulty reports: JASC 6240

A list on [JASC 6240](https://openairdocs.org/jasc/6240.md).

Reports filed under 6240 · Main Rotor Indicating System, newest first.

Page 1 of 14 · 677 reports

- [SDR QR9R2026102200003](https://openairdocs.org/sdr/QR9R2026102200003.md): Sensor · failed · Oct 22, 2026 · Bolkms BK117C2
  > NR NEEDLE DROPPED TO ZERO INTERMITTENTLY AFTER 1.5 HRS OF FLIGHT. REMOVED AND REPLACED #1 XMSN SPEED PICK UP SENSOR IAW AMM 62-41-00, 4-1.
- [SDR QR9R2026091600001](https://openairdocs.org/sdr/QR9R2026091600001.md): Sensor · intermittent · Sep 16, 2026 · Bolkms BK117C2
  > LOW ROTOR RPM LT AND AUDIO INTERMITTENTLY ACTIVE WHILE HOVER TAXIING, ALL OTHER INDICATIONS WERE NORMAL. A TESTFLIGHT EVAL FOUND UPON LANDING ON THE PAD AND REDUCING COLLECTIVE, THE ROTOR RPM AUDIO AND LIGHT ILLUMINATED WITH ROTOR RPM AT 96.8%. WHEN INCREASING
- [SDR QR9R2026081800001](https://openairdocs.org/sdr/QR9R2026081800001.md): Sensor · erratic · Aug 18, 2026 · Bolkms BK117C2
  > ROTOR RPM INDICATOR GAVE ERRATIC INDICATIONS FROM 101% TO 80% DURING FLIGHT. THE ROTOR LOW WARNING LIGHT INDICATION FLUCTUATED INTERMITTENTLY, NEVER STAYING ON. THE LOW ROTOR AUDIO NEVER SOUNDED OFF. REMOVED AND REPLACED THE SPEED PICKUP SENSOR IAW AMM 62-41-0
- [SDR QR9R2026042000001](https://openairdocs.org/sdr/QR9R2026042000001.md): Sensor · faulty · Apr 20, 2026 · Bolkms BK117C2
  > AFTER STARTING ENGINE #2, INITIALLY NR APPEARED ON THE TRIPLE TACH AND MATCHED #2 N2, BUT THEN RETURNED TO 0. A BATTERY DISCONNECT/RESET DID NOT RESOLVE THE PROBLEM. REMOVED AND REPLACED SPEED PICK-UP SENSOR.
- [SDR QR9R2025110300002](https://openairdocs.org/sdr/QR9R2025110300002.md): Sensor · faulty · Nov 3, 2025 · Bolkms BK117C2
  > RRPM GAUGE WOULD DROP TO ZERO INTERMITTENTLY IN FLIGHT WITH LOW RRPM AUDIO. ALL OTHER ENGINE INDICATORS WERE NORMAL. HAPPENED SEVERAL TIMES IN FLIGHT. A TEST FLIGHT EVAL FOUND ROTOR RPM WENT TO 0 WHEN INCREASING COLLECTIVE PRIOR TO TAKEOFF TWO TIMES. RPM ON TR
- [SDR QR9R2025103000001](https://openairdocs.org/sdr/QR9R2025103000001.md): Sensor · faulty · Oct 30, 2025 · Bolkms BK117C2
  > TRIPLE TACH FAILED DURING START UP. NR FAILED TO SYNC, THEN WOULD DROP TO 0. AFTER SEVERAL SECONDS IT WOULD MATCH TO N2 AND THEN REVERT BACK TO ZERO. HAPPENED CONSISTENTLY 4 TIMES. REMOVED AND REPLACED SPEED PICK-UP SENSOR IAW AMM 62-41-00, 4-1. T/P MOC GOOD.
- [SDR QR9R2025091700001](https://openairdocs.org/sdr/QR9R2025091700001.md): Sensor · faulty · Sep 17, 2025 · Bolkms BK117C2
  > ROTOR TACH INTERMITTENT. TEST FLIGHT EVAL FOUND ROTOR TACH AND DIGITAL READOUT INTERMITTENT ON THE GROUND BUT WORKS FINE IN FLIGHT. THE ROTOR INDICATION DECREASES AND RETURNS TO NORMAL WHEN THE COLLECTIVE IS APPLIED ON THE GROUND. REMOVED AND REPLACED SPEED PI
- [SDR QR9R2025052900003](https://openairdocs.org/sdr/QR9R2025052900003.md): Sensor · faulty · May 29, 2025 · Bolkms BK117C2
  > APPROXIMATELY ONE MINUTE AFTER FIRST ENGINE START, BOTH NR DISPLAYS (TRIPLE TACH AND VEMD SYSTEM PAGE) DROPPED TO INDICATING ZERO RPM. REMOVED AND REPLACED NR SPEED SENSOR IAW AMM 62-41-00, 4-1. MOC SUCCESSFULLY COMPLETED.
- [SDR QR9R2025051600001](https://openairdocs.org/sdr/QR9R2025051600001.md): Sensor · faulty · May 16, 2025 · Bolkms BK117C2
  > FAULTY TRIPLE TACHOMETER NR INDICATION WITH TWIST GRIPS IN FLIGHT (INTERMITTENT 101 TO 0 INDICATIONS WITH W/U DISPLAY AND AUDIO). REMOVED AND REPLACED NR SENSOR IAW AMM 62-41-00, 41. MOC OK.
- [SDR QR9R2025040900001](https://openairdocs.org/sdr/QR9R2025040900001.md): Sensor · faulty · Apr 9, 2025 · Bolkms BK117C2
  > LOW ROTOR RPM LIGHT ON THE WU WITH ASSOCIATED TONE CAME ON INADVERTANTLY 6 TIMES DURING A 30 MINUTE FLIGHT. DURING TROUBLESHOOTING OF MAIN ROTOR RPM SYSTEM, FOUND RPM MONITORING SYSTEM TO BE WORKING. RPM SENSOR IS AT FAULT. REMOVED AND REPLACED SPEED PICK-UP (
- [SDR QR9R2024101600001](https://openairdocs.org/sdr/QR9R2024101600001.md): Sensor · intermittent · Oct 16, 2024 · Bolkms BK117C2
  > DURING FLIGHT, ROTOR RPM INDICATION DROPPED TO 0 THEN RETURNED TO NORMAL FOUR TIMES TOTAL. TROUBLESHOOTING FOUND THE MAIN ROTOR RPM SENSOR INDICATED INTERMITTENTLY. TRIPLE TACHOMETER INDICATOR FUNCTIONED NORMALLY ON SIGNAL GENERATOR. REMOVED AND REPLACED SPEED
- [SDR QR9R2024100800002](https://openairdocs.org/sdr/QR9R2024100800002.md): Sensor · failed · Oct 8, 2024 · Bolkms BK117C2
  > NR FAILURE ON TRIPLE TACH DURING FLIGHT RESULTING IN AN UNSCHEDULED LANDING. REMOVED AND REPLACED SPEED PICK-UP SENSOR IAW AMM 62-41-00, 4-1. T/P MOC COMPLETED IAW AMM 005-60-00, 6-12. CHECK FOUND GOOD.
- [SDR QR9R2024080700001](https://openairdocs.org/sdr/QR9R2024080700001.md): Pickup · failed · Aug 7, 2024 · Bolkms BK117C2
  > DURING FLIGHT, TRIPLE TACH FAILED WHEN REDUCING TWIST GRIP FROM FLIGHT TO IDLE. A TEST FLIGHT EVAL REVEALED ROTOR INDICATION GOES TO ZERO BOTH ANALOG AND DIGITAL. ROTOR RPM SPEED PICK-UP FAILED INSPECTION IAW AMM 62-41-00, 4-1 PROCEDURE E1. REMOVED AND REPLACE
- [SDR QR9R2024032500001](https://openairdocs.org/sdr/QR9R2024032500001.md): Pickup · failed · Mar 25, 2024 · Bolkms BK117C2
  > ON START UP, NR WAS AT IDLE THEN BEGAN FLUCTUATING TO ALMOST ZERO WITH BOTH ENGINES AT IDLE. REMOVED AND REPLACED SPEED PICK-UP IAW AMM 62-41-00, 4-1. MOC SUCCESSFULLY COMPLETED; NO FAULTS NOTED.
- [SDR QR9R2024013100001](https://openairdocs.org/sdr/QR9R2024013100001.md): Indicator · fluctuates · Jan 31, 2024 · Bolkms BK117C2
  > DURING HOVER, ROTOR TACH WOULD DROP TO 0 SEVERAL TIMES, THEN GO BACK TO NORMAL. REMOVED AND REPLACED TRIPLE INDICATOR IAW AMM 77-14-00, 4-1.
- [SDR YV3R2023120100590](https://openairdocs.org/sdr/YV3R2023120100590.md): Dual Tachometer · defective · Nov 11, 2023 · Robsin R44
  > CUSTOMER REPORTED DUAL TACHOMETER ASSEMBLY P/N: C792-5 ENGINE NEEDLE WAS OVERREADING 2%.
- [SDR YV3R2023120100589](https://openairdocs.org/sdr/YV3R2023120100589.md): Warning System · defective · Nov 11, 2023 · Robsin R22BETAII
  > CUSTOMER REPORTED WARNING UNIT ASSEMBLY, LOW RPM P/N: A569-5 WAS INOPERATIVE.
- [SDR 2023FA0000766](https://openairdocs.org/sdr/2023FA0000766.md): Gauge · debonded · Nov 7, 2023 · N240SF · Bolkms BK117C2
  > MAST MOMENT WAS EXCEEDED IN A HOVER. LANDED THE AIRCRAFT WITH NO ISSUES. AFTER TROUBLESHOOTING FOUND THE STRAIN GAUGE IN THE MAST HAD DEBONDED CAUSING A FALSE INDICATION IN THE COCKPIT.
- [SDR QR9R2023103100001](https://openairdocs.org/sdr/QR9R2023103100001.md): Pickup · failed · Oct 31, 2023 · Bolkms BK117C2
  > TRIPLE TACH/ROTOR RPM FAILURE DURING FLIGHT. DURING ROTOR SPEED FAILURE TROUBLESHOOTING, FOUND NR SENSOR BAD DURING FUNCTION TEST OF THE ROTOR SPEED MONITORING SYS AMM 62-41-00, 5-1. REMOVED AND REPLACED SPEED PICK-UP; LIMITED TEST FLIGHT SUCCESSFULLY COMPLETE
- [SDR YV3R2023111500586](https://openairdocs.org/sdr/YV3R2023111500586.md): Warning Unit · defective · Oct 19, 2023 · Robsin R44RAVENII
  > CUSTOMER REPORTED WARNING UNIT, LOW RPM P/N: A569-9 PART FAILURE, HORN LIGHT STAYS ON.
- [SDR QR9R2023071900001](https://openairdocs.org/sdr/QR9R2023071900001.md): Pickup · illuminated · Jul 19, 2023 · Bolkms BK117C2
  > IN FLIGHT, VARNAR CAUTION APPEARED THREE TIMES. THE RPM R LIGHT AND AUDIO APPEARED WITH RPM R INDICATING 0% MULTIPLE TIMES. REMOVED AND REPLACED SPEED PICK-UP SENSOR IAW 62-41-00, 4-1. MOC SUCCESSFULLY COMPLETED.
- [SDR JBZA20230706001](https://openairdocs.org/sdr/JBZA20230706001.md): Unknown · unknown · Jul 2, 2023 · N319RX · Airbus EC135P3
  > TRIPLE TACHOMETER INDICATIONS LOST FOR # 1, #2 ENGINES AND MAIN ROTOR TRANSMISSION
- [SDR YV3R2023051600567](https://openairdocs.org/sdr/YV3R2023051600567.md): Relay · inoperative · May 10, 2023 · N944VB · Robsin R44RAVENII
  > CUSTOMER REPORTED RELAY ASSEMBLY P/N: B280-12 WAS INOPERATIVE (NO LOW RPM LIGHT OR HORN).
- [SDR YV3R2023042700559](https://openairdocs.org/sdr/YV3R2023042700559.md): Warning Unit · defective · Apr 12, 2023 · N522SB · Robsin R22BETAII
  > CUSTOMER REPORTED WARNING UNIT ASSEMBLY, LOW RPM P/N: A569-5 LOW ROTOR HORN SOUND INOPERATIVE.
- [SDR YV3R2023042700558](https://openairdocs.org/sdr/YV3R2023042700558.md): Dual Tachometer · defective · Apr 11, 2023 · N7102Z · Robsin R44
  > CUSTOMER REPORTED DUAL TACHOMETER P/N: C792-5 NEEDLES GET STUCK BETWEEN 68% - 90%.
- [SDR YV3R2023042700555](https://openairdocs.org/sdr/YV3R2023042700555.md): Warning Unit · defective · Mar 30, 2023 · N313DD · Robsin R22BETAII
  > CUSTOMER REPORTED WARNING UNIT P/N: A569-5 WAS INOPERATIVE.
- [SDR ULXR307FD21323](https://openairdocs.org/sdr/ULXR307FD21323.md): Sensor · failed · Feb 13, 2023 · N307FD · Bell 505
  > NR SENSOR FAILURE. NR WENT TO ZERO IN FLIGHT. CAUSED TRANSPONDER TO GO OFF LINE AS AIRCRAFT THOUGHT IT WAS ON THE GROUND DUE TO ZERO ROTOR RPM.
- [SDR YV3R2022111700547](https://openairdocs.org/sdr/YV3R2022111700547.md): Dual Tachometer · defective · Oct 31, 2022 · Robsin R44RAVENII
  > CUSTOMER REPORTED DUAL TACHOMETER ASSEMBLY P/N: C792-5 FLUCTUATES CAUSING OVER RPM.
- [SDR QR9R2022101900002](https://openairdocs.org/sdr/QR9R2022101900002.md): Indicator · intermittent · Oct 19, 2022 · Bolkms BK117C2
  > DURING FLIGHT, TRIPLE TACH INTERMITTENT FAILURE. REPLACED TRIPLE TACH IAW 62-41-00,4-3. COMPLETED GROUND RUN AND FLIGHT IAW THE RFM. NO DISCREPANCIES NOTED.
- [SDR YV3R2022111700546](https://openairdocs.org/sdr/YV3R2022111700546.md): Warning Unit · inoperative · Oct 18, 2022 · Robsin R22
  > CUSTOMER REPORTED WARNING UNIT ASSEMBLY P/N: A569-5 WAS INOPERATIVE OUT OF THE BOX.
- [SDR YV3R2022101500545](https://openairdocs.org/sdr/YV3R2022101500545.md): None · faulty · Oct 5, 2022 · Robsin R22BETAII
  > CUSTOMER REPORTED WARNING UNIT ASSEMBLY (LOW RPM) P/N: A569-5 WAS NOT SERVICEABLE.
- [SDR YV3R2022100700544](https://openairdocs.org/sdr/YV3R2022100700544.md): None · failed · Sep 15, 2022 · Robsin R44RAVENII
  > CUSTOMER REPORTED WARNING UNIT ASSEMBLY (LOW RPM) P/N: A569-9 FAILED TO ACTIVATE LIGHT AND HORN.
- [SDR YV3R2022100700543](https://openairdocs.org/sdr/YV3R2022100700543.md): None · defective · Sep 8, 2022 · Robsin R66
  > CUSTOMER REPORTED WARNING UNIT ASSEMBLY (LOW RPM) P/N: A569-11 LOW ROTOR WARNING LIGHT AND SOUND (AUDIO) CAME ON DURING THE FIRST FLIGHT.
- [SDR YV3R2022052600529](https://openairdocs.org/sdr/YV3R2022052600529.md): None · defective · May 3, 2022 · N10MW · Robsin R66
  > CUSTOMER REPORTED WARNING UNIT ASSEMBLY P/N: A569-11 WAS INOPERATIVE.
- [SDR YV3R2022050400527](https://openairdocs.org/sdr/YV3R2022050400527.md): None · defective · Apr 22, 2022 · N6240 · Robsin R22
  > CUSTOMER REPORTED WARNING UNIT ASSEMBLY (RPM) P/N: A569-5 WAS INOPERATIVE.
- [SDR YV3R2022050400525](https://openairdocs.org/sdr/YV3R2022050400525.md): None · defective · Apr 9, 2022 · N2444 · Robsin R44RAVENII
  > CUSTOMER REPORTED DUAL TACHOMETER ASSEMBLY P/N: C792-4 NEEDLES WERE JUMPING WITHIN UNIT.
- [SDR QR9R20220330001](https://openairdocs.org/sdr/QR9R20220330001.md): Pickup · faulty · Mar 30, 2022 · Bolkms BK117C2
  > FIVE SECONDS AFTER STARTING #1 ENGINE, NR DROPPED TO ZERO THEN RETURNED 3 MINUTES LATER. AFTER RESET, NR LAGGED GOING INTO FLIGHT. TOOK OFF, DROPPED TO ZERO 3 TIMES IN FIVE MINUTE PERIOD. REPLACED SPEED PICK-UP, MOC SUCCESSFULLY COMPLETED.
- [SDR YV3R2022050400524](https://openairdocs.org/sdr/YV3R2022050400524.md): None · defective · Feb 14, 2022 · Robsin R44RAVENII
  > CUSTOMER REPORTED WARNING UNIT ASSEMBLY P/N: A569-9 FAILED TO REACT TO RPM'S.
- [SDR YV3R2022021600517](https://openairdocs.org/sdr/YV3R2022021600517.md): Dual Tachometer · defective · Jan 27, 2022 · Robsin R22BETAII
  > CUSTOMER REPORTED DUAL TACHOMETER ASSEMBLY P/N: A792-4 INDICATED INCORRECT READING.
- [SDR YV3R2022021000515](https://openairdocs.org/sdr/YV3R2022021000515.md): None · none · Jan 5, 2022 · Robsin R22BETAII
  > CUSTOMER REPORTED WARNING UNIT (LOW RPM) P/N" A569-5 WAS NOT FUNCTION AT FULL RPM.
- [SDR YV3R2022021000514](https://openairdocs.org/sdr/YV3R2022021000514.md): None · none · Dec 20, 2021 · Robsin R66
  > CUSTOMER REPORTED WARNING UNIT ASSEMBLY (LOW RPM) P/N: A569-11 LOW RPM LIGHT NEVER WENT OUT. CORRECTION: UNIQUE CONTROL # YV3R2022021000514, 3B (MANUFACTURER): SHOULD BE "RROYCE"
- [SDR YV3R2022021000513](https://openairdocs.org/sdr/YV3R2022021000513.md): None · defective · Dec 20, 2021 · Robsin R66
  > CUSTOMER REPORTED WARNING UNIT ASSEMBLY (LOW RPM) P/N: A569-11 LOW RPM LIGHT NEVER WENT OUT.
- [SDR QR9R20211207003](https://openairdocs.org/sdr/QR9R20211207003.md): Pickup · faulty · Dec 7, 2021 · Bolkms BK117C2
  > ONCE THE #1 ENGINE WAS STARTED, NO NRO INDICATIONS. CALLED MAINTENANCE TO TROUBLESHOOT, RESET BAT AND GENERATORS FOR TROUBLESHOOTING. FOUND THAT AFTER START N2 NEEDLE INDICATED PROPERLY WHILE ROTOR TACH REMAINED AT ZERO. ADDITIONALLY, NR ON THE SYSTEM STATUS P
- [SDR YV3R2021100700497](https://openairdocs.org/sdr/YV3R2021100700497.md): Dual Tachometer · defective · Sep 22, 2021 · N808LB · Robsin R44
  > CUSTOMER REPORTED DUAL TACHOMETER P/N: C792-4 WAS INTERMITTENT.
- [SDR YV3R2021090100492](https://openairdocs.org/sdr/YV3R2021090100492.md): Dual Tachometer · defective · Aug 24, 2021 · Robsin R22
  > CUSTOMER REPORTED DUAL TACHOMETER ASSEMBLY P/N: A792-4 ENGINE TACH NEEDLE READS 70% WITH ENGINE SHUT DOWN.
- [SDR YV3R2021072200471](https://openairdocs.org/sdr/YV3R2021072200471.md): Warning Unit · defective · Jul 12, 2021 · N882GD · Robsin R44RAVENII
  > CUSTOMER REPORTED WARNING UNIT P/N: A569-9 HORN (AUDIO) DID NOT SOUND.
- [SDR YV3R2021070700469](https://openairdocs.org/sdr/YV3R2021070700469.md): Dual Tachometer · defective · Jun 30, 2021 · N144KD · Robsin R44RAVENII
  > CUSTOMER REPORTED DUAL TACHOMETER P/N: C792-4 ROTOR NEEDLE READS LOW 2-5%.
- [SDR YV3R2021070700468](https://openairdocs.org/sdr/YV3R2021070700468.md): Dual Tachometer · defective · Jun 29, 2021 · N46SG · Robsin R44
  > CUSTOMER REPORTED DUAL TACHOMETER P/N: C792-4 ROTOR NEEDLE WAS INTERMITTENT, AND THEN FAIL COMPLETELY.
- [SDR YV3R2021060900461](https://openairdocs.org/sdr/YV3R2021060900461.md): Dual Tachometer · defective · Jun 1, 2021 · N715SG · Robsin R44
  > CUSTOMER REPORTED DUAL TACHOMETER P/N: C792-4 ENGINE NEEDLE PEGS WITH POWER APPLIED.
- [SDR YV3R2021052800458](https://openairdocs.org/sdr/YV3R2021052800458.md): Warning Unit · defective · May 19, 2021 · N73PT · Robsin R66
  > CUSTOMER REPORTED WARNING UNIT (LOW RPM) P/N: A569-11 WAS NOT FUNCTIONING CORRECTLY, LOW RPM LIGHT ILLUMINATES WITH HORN SOUNDING.

Next page: https://openairdocs.org/jasc/6240/reports.md?page=2

## The whole list in SQL

Runs in DuckDB 1.2 or later on the release's Parquet files over HTTPS:

```sql
SELECT sdr_id, difficulty_date, n_number, aircraft_make, aircraft_model, part_name, part_condition, jasc_code, discrepancy
FROM 'https://openairdocs.org/data/latest/faa_service_difficulty_report.parquet'
WHERE jasc_code = '6240'
ORDER BY difficulty_date DESC
```

This list as a web page: https://openairdocs.org/jasc/6240/reports

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