ATL03FA065 · Sikorsky S-61A
Sikorsky S-61A · Accident: airframe, component or system failure while maneuvering
From Kimble, TN to Kimble, TN
Event
- NTSB case
- ATL03FA065
- 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
- 1 · 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
Sikorsky S-61A
- Aircraft type
- Sikorsky S-61
- 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
- N81664
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Kimble, TNTo Kimble, TN
- Aircraft age
- Not recorded
- 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 133: Rotorcraft Ext. Load
- 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 · hover out of ground effect
- First occurrenceThe 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
- Airframe, component or system failure
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Tree(s)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Pilot in command › Airspeed, inadequate
- Pilot in command › Altitude, inadequate
- Pilot in command › Height/velocity curve, exceeded
- Rotor drive system, freewheeling unit(other) › Slipped
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
According to the co-pilot, the purpose of the flight was to move logs from one-drop area to another using a 150-foot long line attached to the helicopter. On the second airlift, shortly after the logs were laid on the ground, a shudder was felt in the helicopter airframe followed by a slight yaw to the right. On the instrument panel, there was a needle jump in the triple tachometer gauge followed by a very loud bang. The helicopter began a violent left hand descending spin towards the ground. As the helicopter descended, it collided with trees and subsequently the ground. Within seconds the helicopter burst into flames. Examination of the helicopter revealed, the cockpit and the main fuselage of the helicopter were fire damaged. The tail boom was partially fire damaged, and tail rotor blades were bent and connected to the tail rotor transmission. The tail rotor drive shaft was intact and connected to the main rotor transmission. The five main rotor blades were connected to the main rotor head and displayed buckling and deformation damage. Further examination of the main transmission revealed that the left input free wheel unit turned and freewheeled, but made a grinding noise when turned in the freewheel direction. Further examination of the left input free wheel unit revealed the gear housing was worn with numerous roller impressions on the gear housing. The rollers were also rough in surface appearance. The right input free wheel unit operated in both directions without making any detectable noise. Record review of the input free wheel unit assemblies were conducted, and it was reported that the time since overhauled on the components was 960 hours. Sikorsky recommends that free wheel unit times should between overhauls of 350 hours. The FAA-H-8083-21 rotor Flying Handbook notes that pilots need to be familiar with the Height/Velocity diagrams for the particular models of rotorcraft the pilots are flying. Operating at the altitudes and airspeeds shown within the cross-hatched or shaded areas of the Height/Velocity diagram may not allow enough time for the critical transition from powered flight to autorotation. The helicopter operated about 150 feet above the ground inside the shaded area of the Height/ Velocity Curve.
Probable cause
The interruption of rotor system drive power due to the input free wheeling unit malfunctioning , and the pilot's operation of the helicopter in the critical area of the height-velocity curve.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ATL03FA065
- Event ID
- 20030326X00395
- Case number
- ATL03FA065
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
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: f3dd2b0e3cb51b89052217ecfaef7d7bac44d2d3ea72fdab9489f1f0b7b6124f; retrieved 2026-09-20T19:22:12.388Z.