Bell 47G5 N7836S

Summary

On 11 September 2013 at about 14:15 local time, a Bell 47G5 registered N7836S, operated by Wilbur-Ellis Co, was involved in an accident near King City, 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

11 September 2013 at 14:15

Classification

Accident

Location

King City, California, United States

Nearest airport

Mesa Del Rey Airport (KIC)

Coordinates

36.1919, -120.9422

Aircraft

Bell 47G5

Registration

N7836S

Category

Helicopter

Year built

1967

Engines

1

Operator

Wilbur-Ellis Co

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

King City → King City

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR13LA404

Nobody was injured.

The failure of the helicopter’s center frame tube due to a fatigue crack and corrosion originating from a welded surface. Contributing to the accident was maintenance personnel’s inadequate inspection of the helicopter during its most recent 100-hour inspection.

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

Read the full NTSB narrative

The pilot reported that he was flying low over a field when he heard a "loud bang." He initiated a precautionary landing, during which, the helicopter started to spin. The pilot lowered the collective, and the helicopter subsequently landed hard on a road. Postaccident examination of the helicopter structure revealed that one of the center frame tubes, located just aft of the cabin, had separated due to a fracture. Examination of the fracture surface revealed that a fatigue fracture initiated in the tube at the root of a fillet weld associated with a reinforcing fillet welded axially along the tube. The fatigue crack propagated through the thickness of the tube and circumferentially around the tube from both sides of the weld root. Darker corrosion product found on the fracture face indicated that the preexisting fatigue crack had been exposed to atmospheric elements. The tube fracture occurred in single-sided bending consistent with in-flight airframe loads. The helicopter's most recent 100-hour inspection occurred about 1 month before the accident. According to manufacturer's guidance, the 100-hour inspection required, in part, an inspection of all structural tubing and fittings for cracks, cuts, bends, corrosion, distortion, and damage. If maintenance personnel had adequately inspected this area, they might have identified the degradation of the tube.

Quoted verbatim from the NTSB record.