Bell 47D1 N903B

Summary

On 31 October 2004 at about 17:22 local time, a Bell 47D1 registered N903B was involved in an accident near San Martin, California, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

31 October 2004 at 17:22

Classification

Accident

Location

San Martin, California, United States

Nearest airport

South County Airport of Santa (E16)

Coordinates

37.0817, -121.5969

Aircraft

Bell 47D1

Registration

N903B

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

San Jose → San Martin

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX05LA022

Nobody was injured.

A loss of power for undetermined reasons.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The helicopter experienced a loss of engine power and rolled over during an attempted autorotation to a soft, muddy field. The helicopter departed for a 22-nautical mile training flight with 10 gallons of fuel remaining in the 28-gallon fuel tank. While en route, both the certified flight instructor (CFI) and student pilot noted that an unusually high application of carburetor heat was required to keep the inlet temperature needle within the normal range. With the intention of entering the traffic pattern at the destination airport, the student pilot initiated a descent and maneuvered the helicopter in a right turn. With the helicopter configured in the right turn, about 500 feet above ground level (agl), the engine experienced a momentary power interruption and subsequently stopped. The student pilot executed an autorotation and the helicopter touched down in a crop field. The right skid dug into the soft muddy field, resulting in the helicopter rotating around the skid and coming to rest on its right side. The fuel tank contained about 5 gallons of fuel just prior to the accident. Due to the orientation of the fuel outlet port inside the fuel tank, the helicopter is susceptible to unporting with low quantities of fuel present during maneuvers. With the outlet located on the left side of the tank, when a helicopter is in a right turn with minimal fuel onboard, the outlet can intake air resulting in fuel starvation to the engine. According to a standard reference icing probability chart, the atmospheric conditions present at the time of the accident were in the range considered favorable for carburetor ice formation.

Quoted verbatim from the NTSB record.