Sikorsky S-61A accident near Kimble, Tennessee, March 23, 2003
On March 23, 2003 at about 2:00 pm local time, a Sikorsky S-61A (helicopter), registered N81664, was destroyed in an accident near Kimble, Tennessee. It was an other work-use flight under external-load helicopter rules (Part 133). 1 person was killed and 1 person was seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made November 2, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- March 23, 2003 · about 2:00 pm local time · cases in 2003
- Place
- Kimble, Tennessee · map
- Type
- Accident · collision on the ground
- Injuries
- 1 person was killed and 1 person was seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Sikorsky S-61A · all S-61As on the register
- Registration
- N81664 · no longer on the register · serial 61063
- Damage
- Destroyed
- Flight
- Other work-use flight · external-load helicopter rules (Part 133)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: commercial pilot
- Ratings: rotorcraft: helicopter
- Flight time: 29,325 hours in all; 5,300 in this make and model; 120 in the last 90 days; 4,500 as pilot in command
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: left
- Injury: fatal
Co-pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane; rotorcraft: helicopter
- Flight time: 1,341 in this make and model; 171 in the last 90 days; 81 in the last 30 days
- Last flight review: September 22, 2002
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: rgt
- Injury: serious injuries
The aircraft
- Airframe total time: 18,579 hours
- Last inspection: continuous airworthiness programme, March 22, 2003; 3 hours since
- Maximum gross weight: 10,500 lb
- Seats: 2
- Landing gear: fixed
- Engine 1: General Electric CT58-140-1 (turboshaft); 0 hours total
- Engine 2: General Electric CT58-140-1 (turboshaft); 0 hours total
- Fire on the ground
The flight
- Departed from: Kimble TN at 1:30 pm
- Destination: Kimble TN
- Flight plan: none
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: at 0 knots
- Visibility: 10 statute miles
- Sky: a few clouds at 10,000 ft
- Temperature: 48°F (9°C), dew point 45°F (7°C)
- Altimeter: 30.04 inHg
- Observation at 1:53 pm from CHA, 41 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Connections how this case links to the rest of the register
- N81664: not on the register today · the record of its deregistration
- Sikorsky S-61 54 registered today · the model family and its accident history
- Sikorsky 827 aircraft on the register
- Engine: General Electric CT58-140-1 20 aircraft carry this series today · as the NTSB recorded it
- Engine: General Electric CT58-140-1 20 aircraft carry this series today · as the NTSB recorded it
- Accidents and incidents in Tennessee 1,198 since 1982 · 231 in the last ten years
- Tennessee 6,535 aircraft registered
The whole map of how records connect · these connections as data: /graph/accident/ATL03FA065.json.
The bigger picture in Aviation Analytics: accidents over time since 1982, by model, by phase of flight and conditions, by place and on the map.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text does not name anyone involved, its policy at this time. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.