Hiller UH-12E accident near Culpeper, Virginia, March 25, 2011
On March 25, 2011 at about 4:38 pm local time, a Hiller UH-12E (helicopter), registered N4033P, was substantially damaged in an accident during maneuvering (low-alt flying) near Culpeper, Virginia. It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
Mechanical failure of the transmission for reasons that could not be determined because the transmission could not be torn down.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- March 25, 2011 · about 4:38 pm local time
- Place
- Culpeper, Virginia · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Hiller UH-12E · all UH-12Es on the register
- Registration
- N4033P · no longer on the register · serial 5178
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
The aerial application flight had departed and was enroute to apply agricultural product to a nearby field; the engine rpm increased uncommanded and the pilot performed a forced landing in an open field. The pilot reported that after the helicopter came to rest, he exited and put his hand on the transmission, which was hot. He then felt the transmission cooler, which he stated was similar in temperature to the surrounding air temperature. Seven days before the accident, a continued airworthiness inspection was performed on the helicopter; the main transmission gearbox oil was drained, and the main rotor transmission was removed to facilitate engine removal. Particulate matter may have been inadvertently left in or around the main rotor transmission during its removal. During the flight the particulate matter may have become lodged in one of the journals inside the transmission and caused its failure, which then allowed the engine to overspeed and the helicopter to lose lift. However, the investigation was not able to conclusively determine the cause of the failure because the transmission could not be secured for a teardown.
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
- Powerplant sys/comp malf/fail during maneuvering (low-alt flying) defining event
- Loss of lift during maneuvering (low-alt flying)
- Autorotation Hard landing
The NTSB's findings
- cause Aircraft › Aircraft propeller/rotor › Main rotor drive › (general) › Malfunction
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; instrument: airplane; rotorcraft: helicopter
- Flight time: 13,000 hours in all; 1,500 in this make and model; 7 in the last 90 days; 7 in the last 30 days; 13,000 as pilot in command
- Last flight review: October 23, 2009
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 3,340 hours
- Last inspection: continuous airworthiness programme, March 18, 2011; 2 hours since
- Maximum gross weight: 2,800 lb
- Seats: 4
- Landing gear: fixed
- Engine: Lycoming VO-540-C2A (piston); 0 hours total
- Operator: Kritter Cropdusting, INC
The flight
- Departed from: Culpeper VA at 4:15 pm
- Destination: Culpeper VA
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 240° at 5 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 46°F (8°C), dew point 28°F (-2°C)
- Altimeter: 30.02 inHg
- Observation at 4:20 pm from CJR, 5 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 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.
Other NTSB records under N4033P the same tail number, which may have belonged to a different aircraft at the time
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.