# SDR QR9R2026091600001

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: September 16, 2026
- Submitted: September 16, 2026
- 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: 9695
- Aircraft time: 5,046 hours
- System (JASC): [6240 · Main Rotor Indicating System](https://openairdocs.org/jasc/6240)
- Part: Sensor
- Part number: 430106202
- Condition: Intermittent
- Location: Rotor Tach
- Stage of operation: HO
- How discovered: V
- Nature of condition: F
- Precautionary procedure: C
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/QR9R2026091600001

## Discrepancy

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 COLLECTIVE THE ROTOR RPM LIGHT STAYED ON AND THE HIGH ROTOR RPM AUDIO ACTIVATED AT 99.4% RPM. WHEN DOING AN OPERATIONAL CHECK OF THE RPM WARNING SYSTEM BEFORE FLIGHT IT CORRECTLY ACTIVATED AT 95.1% RPM. ACFT WAS TESTED WITH A SIGNAL GENERATOR AND WORKED CORRECTLY INDICATING THE SENSOR IS GIVING ERRONEOUS FREQUENCIES CAUSING THE WARNING SYSTEM TO FUNCTION INCORRECTLY. REMOVED AND REPLACED NR SENSOR IAW AMM 62-41-00, 4-1. MOC SUCCESSFULLY COMPLETED.

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