ERA16LA216 · Robinson Helicopter R44 UNDESIGNAT
Ryan Rotors Robinson Helicopter R44 UNDESIGNAT · Accident: powerplant system/component malfunction/failure while maneuvering
From Plymouth Municipal Airport (PYM) to Plymouth Municipal Airport (PYM)
Event
- NTSB case
- ERA16LA216
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Robinson Helicopter R44 UNDESIGNAT
- Aircraft type
- Robinson R44
- Category
- Helicopter
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N141TM
- Operator
- Ryan Rotors
- Onboard fatalities
- Unknown
- Route
- From Plymouth Municipal Airport (PYM), Plymouth, MATo Plymouth Municipal Airport (PYM), Plymouth, MA
- Aircraft age
- About 14 years (built 2002)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Maneuvering · low-altitude flying
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Powerplant system/component malfunction/failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft systems
- Personnel issues › Task performance
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The commercial pilot reported that, during an aerial photography flight, the helicopter was about 300 ft above a pond when it experienced an engine overspeed, followed by a loss of engine power. The pilot subsequently entered an autorotation to shallow water.
Examination of the engine revealed that the No. 2 cylinder head rocker shaft bosses, the No. 2 intake valve upper spring, and the No. 3 intake valve spring seat were fractured, consistent with an engine overspeed. Examination of the airframe revealed that the engine cooling fan shaft had separated. Without the resistance of the fan shaft, the engine oversped, which resulted in sufficient engine damage for the engine to lose total power. The aft face of the fan shaft's lower sheave exhibited caked-on grease, consistent with grease leaking beyond the lower forward clutch actuator bearing seal for a prolonged period of time. Metallurgical examination of the bearing revealed that its rollers were seized, and no grease was recovered, consistent with a lack of lubrication.
The helicopter manufacturer's maintenance manual required that the entire airframe be overhauled every 2,200 hours, which would include an overhaul of the engine cooling fan driveshaft lower bearing and seal. Review of maintenance records revealed that, due to a maintenance logbook entry error (time since overhaul) that occurred about 9 years before the accident and was carried forward, the helicopter had been operated about 52 hours beyond the mandatory airframe overhaul time limit. The manual also required that the lower clutch actuator bearings be lubricated every 300 hours or 3 years, whichever occurred first. Although the failed bearing had been lubricated with grease both about 1 year and 2 years preceding the accident, there was no record indicating that the bearing had been lubricated with grease during the preceding 4 years 11 months and 685.1 hours of operation, which likely damaged or degraded the bearing and led to its failure during the accident flight.
Probable cause
The inadequate maintenance of the lower forward clutch actuator bearing for a prolonged period of time, which resulted in a bearing failure. Contributing to the accident was an erroneous maintenance entry, which resulted in the helicopter being operated beyond its mandatory airframe overhaul time.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ERA16LA216
- Event ID
- 20160618X24627
- Case number
- ERA16LA216
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 2e500b761448204a6dd5d7b9ec4fbc2ac655ebbf48275d7173fc5a520fb25fe3; retrieved 2026-09-16T03:31:21.062Z.