Bell 47G-3B-2 N475AL

Summary

On 14 August 2011 at about 19:45 local time, a Bell 47G-3B-2 registered N475AL, operated by Double Springs Helicopters, was involved in an accident near Los Banos, California, United States. One person was 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

14 August 2011 at 19:45

Classification

Accident

Location

Los Banos, California, United States

Coordinates

37.0000, -120.8667

Aircraft

Bell 47G-3B-2

Registration

N475AL

Category

Helicopter

Engines

1

Operator

Double Springs Helicopters

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Los Banos → Los Banos

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR11LA379

Nobody was injured.

The pilot’s inadequate preflight, and contamination of both the engine compressor section and the main rotor blades, which resulted in reduced performance of the engine and rotor system.

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

Read the full NTSB narrative

During an agricultural application flight, the helicopter had just departed from the elevated landing pad when it experienced a loss of lift, which the pilot thought was a loss of engine power. The pilot attempted to arrest the descent but was unsuccessful before the helicopter hit the trees. Examination of the engine revealed no pre-impact mechanical malfunctions that would have prevented normal operations. Postaccident examination noted that the compressor vanes and both main rotor blades were layered with a substance that had the consistency of peanut butter. As a result of the contamination, the compressor would not operate at its optimum level, which affected the power output performance of the engine. The material on the main rotor blades would also have affected the helicopter’s lift performance. The examination did not reveal what the substance was, but the airplane flew through agricultural products, which may have led to the substance building up on the blades and compressor over time. Had the pilot done a preflight inspection, he may have noticed the contamination in the engine compressor section and the main rotor blades. Because the helicopter was departing from an elevated land platform, after liftoff, the helicopter was immediately out of ground effect, which resulted in an immediate descent that the pilot was unable to arrest.

Quoted verbatim from the NTSB record.