R44 helicopter pilot reported a malfunction of the automatic drive belt tensioner component, which resulted in an immediate uncommanded rise in engine RPM and associated warning lights. The pilot performed an autorotational descent and landed upright in soft mud on the helicopter skids. There were no injuries to the aircraft's occupants.

ACN 2008727 2023-06 Robinson R44 Rotary Wing Aircraft Flight Crew Reports

CruisePart 91

What is ASRS?

The Aviation Safety Reporting System is NASA's voluntary, confidential, non- punitive incident-reporting system, established 1976. Pilots, controllers, dispatchers, and maintenance technicians file reports describing safety- relevant events. NASA de-identifies every report before adding it to the public database. Reports are not investigated by NASA, the FAA, or the NTSB — they represent the reporter's perspective.

Pilot narrative

Verbatim from the de-identified NASA record. First-person account by the reporter. NASA strips identifying details (names, company, specific time); anonymization placeholders are ZZZ, X, Y.

I am writing to share that I experienced a malfunction of a Robinson R44 automatic drive belt tensioner component, while conducting helicopter patrols flying over non-populated terrain. I remember hearing a banging sound, followed by an immediate and uncommanded rise in engine RPM, and the illumination of warning / hazard lights with a loss of perceived power. I immediately initiated an autorotational descent, while Person B reported the situation to Dispatch. The autorotation was concluded successfully with the aircraft landing upright on its skids in a soft field of mud. I then immediately shut down the engine, electrical switches, stopped the rotor blades from rotating, and determined at that point there was no further danger to the occupants of the aircraft. The two souls on board, myself and Person B, both walked away without need for aid, and with both reporting no injuries. I initiated a call to the Chief Pilot to report the mechanical failure, while Person B contacted other personnel for assistance. After an initial inspection of the aircraft and surrounding area, there was no damage to persons or property on the surface and no further damage to the aircraft outside what caused the initial loss of power. After further inspection no damage to flight controls or structural components, to include sheet- metal, skids or blades, was found. The aircraft was later removed from the private party's field via helicopter and transported via trailer to the department’s contracted maintenance facility.

NASA classification — Anomalies

Aircraft Equipment Problem
Inflight Event / Encounter

NASA classification — Assessments

Contributing Factors / Situations: Aircraft · Human Factors
Primary Problem: Aircraft

ASRS reports are voluntarily submitted, de-identified by NASA, and represent the reporter's perspective. The presence of reports on a topic cannot be used to infer prevalence in the National Airspace System. The authoritative source is the NASA ASRS Database Online at asrs.arc.nasa.gov ↗.