# SDR QR9R2025110300002

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: November 3, 2025
- Submitted: November 3, 2025
- Operation: General aviation
- Filed by: [M1 Support Services, repair station QR9R369D](https://openairdocs.org/faa-repair-station/QR9R369D/m1-support-services.md) (OpenAirDocs)
- Make and model: Bolkms BK117C2
- Aircraft serial: 9420
- Aircraft time: 4,232 hours
- System (JASC): [6240 · Main Rotor Indicating System](https://openairdocs.org/jasc/6240)
- Part: Sensor
- Part number: 430106202
- Part serial: 2216917334962
- Condition: Faulty
- Location: Rotor Tach
- Stage of operation: CR
- How discovered: O
- Nature of condition: F
- Precautionary procedure: A
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/QR9R2025110300002

## Discrepancy

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 TRIPLE TACH AND DIGITAL INDICATION WAS 0. REMOVED AND REPLACED RPM SPEED PICK-UP SENSOR IAW AMM 62-41-00, 4-1.

---
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.