Robinson R44 II accident near Cheyenne, Wyoming, August 28, 2015
On August 28, 2015 at about 5:00 pm local time, a 2008 Robinson R44 II (helicopter), registered N440SA, was substantially damaged in an accident during landing near Cheyenne, Wyoming (Cheyenne Regional/Jerry Olson airport). It was a business flight under general aviation rules (Part 91). 3 people were seriously injured and 3 people had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot's improper preflight performance planning, which resulted in a hard landing due to low rotor rpm while operating near maximum gross weight in high density altitude conditions.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 28, 2015 · about 5:00 pm local time
- Place
- Cheyenne, Wyoming · Cheyenne Regional/Jerry Olson · map
- Type
- Accident
- Injuries
- 3 people were seriously injured and 3 people had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Robinson R44 II, built 2008 · all R44 IIs on the register
- Registration
- N440SA · no longer on the register · serial 12260
- Damage
- Substantial damage
- Flight
- Business flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The commercial helicopter pilot and two passengers were conducting a pipeline inspection flight. After picking up the passengers and prior to conducting the inspection, the pilot landed the helicopter at an airport to obtain fuel. During approach for landing, the passengers heard the low rotor rpm warning horn activate, but the helicopter landed normally. The pilot fueled the helicopter, and during the subsequent departure, the low rotor rpm warning horn activated. The pilot was able to "reposition" the helicopter and depart without incident. After completing a portion of the flight, the helicopter returned to a pipeline terminal near the airport for landing. The pilot stated that, during the off-airport landing, the main rotor rpm began to decay, so he lowered the collective and tried to fly "into clean air;" however, the helicopter was too low, and he realized it was going to hit the ground. The pilot increased collective and leveled the helicopter to cushion the impact. The helicopter impacted the ground from an altitude of about 15 ft and slid about 10 ft before coming to rest. The helicopter was operating about 50 lbs under its maximum gross weight, and the density altitude around the time of the accident was about 8,000 ft. Given these conditions, the helicopter's out-of-ground-effect hover ceiling was about 4,400 ft; its in-ground-effect hover ceiling was about 7,700 ft. Therefore, the helicopter would not have been able to hover out of ground effect, but could hover in ground effect. Operating under such conditions could lead to a settling-with-power or low rotor rpm situation if the helicopter became too slow while out of ground effect. It could not be determined whether the pilot conducted preflight performance planning; however, the repeated activation of the low rotor rpm warning suggests that he did not adequately adjust the helicopter's takeoff and landing profiles to account for the flight conditions present at the time of the accident.
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
What happened, in order
- Loss of engine power (partial) during approach
- Hard landing during landing defining event
The NTSB's findings
- cause Personnel issues › Action/decision › Info processing/decision › Expectation/assumption › Pilot
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › (general) › Capability exceeded
- factor Environmental issues › Conditions/weather/phenomena › Temp/humidity/pressure › High temperature › Effect on personnel
Pilot
- Certificate: commercial pilot
- Ratings: instrument: helicopter; rotorcraft: helicopter
- Flight time: 2,700 hours in all; 100 in this make and model
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: rgt
- Injury: minor injuries
The aircraft
- Seats: 4
- Landing gear: fixed
- Engine: Lycoming IO-540-AE1A5 (piston); 0 hours total
- Operator: Submissive Air, Inc
The flight
- Departed from: CYS Cheyenne WY at 4:50 pm
- Destination: KSPF Black Hills SD
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: at 6 knots, gusting 15
- Visibility: 10 statute miles
- Sky: a few clouds at 12,000 ft
- Temperature: 73°F (23°C), dew point 45°F (7°C)
- Altimeter: 30.29 inHg
- Observation at 4:53 pm from KCYS, 3 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | 1 | ||
| Passengers | 2 | 2 |
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.
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 never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.