ERA15LA291 · Sontonastaso MOSQUITO
Sontonastaso MOSQUITO · Accident: loss of engine power (partial) en route
From Jaffrey Airfield Silver Ranch Airport (AFN) to Jaffrey Airfield Silver Ranch Airport (AFN)
Event
- NTSB case
- ERA15LA291
- 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
Sontonastaso MOSQUITO
- Aircraft type
- Sontonastaso MOSQUITO
- 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
- N285XE
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Jaffrey Airfield Silver Ranch Airport (AFN), Jaffrey, NHTo Jaffrey Airfield Silver Ranch Airport (AFN), Jaffrey, NH
- Aircraft age
- Built the same year (2015)
- 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
- En route · cruise
- 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
- Loss of engine power (partial)
- 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 power plant
Approximate · Coordinates from the NTSB case API, not marked as estimated; no uncertainty radius is established.
NTSB narrative
According to the commercial pilot, about 1 hour into a local flight, he felt the helicopter suddenly "kick from loss of torque." He then observed that the engine rpm had dropped to about 30%, and he was unable to increase engine power using the throttle control. The pilot responded by performing an autorotation to an open field. During the landing, the helicopter touched down hard, and the main rotor system struck the tailboom, which resulted in substantial damage to the airframe and tail rotor drive system.
During a postaccident engine run, the pilot found that a faulty wiring crimp resulted in a loss of electrical power to the coil pack of one of the cylinders, which resulted in the engine experiencing a partial loss of power.
Probable cause
A partial loss of engine power due to a faulty electrical wiring crimp in the engine’s ignition system.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ERA15LA291
- Event ID
- 20150729X23324
- Case number
- ERA15LA291
- 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, coordinates. 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: a9d65890dad543a4e3a230412b1048b4f643406722b50c5cf8dde6296f2f1847; retrieved 2026-09-16T02:35:46.812Z.