Bell OH 58C N82857

Summary

On 12 May 2018 at about 03:30 local time, a Bell OH 58C registered N82857, operated by TRI Rotor Spray & Chemical, was involved in an accident near Yuma, Arizona, 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

12 May 2018 at 03:30

Classification

Accident

Location

Yuma, Arizona, United States

Coordinates

32.6861, -114.7239

Aircraft

Bell OH 58C

Registration

N82857

Category

Helicopter

Year built

1970

Operator

TRI Rotor Spray & Chemical

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Somerton → Somerton

Aircraft damage

Substantial

Weather

VMC

Light

Night

NTSB number

WPR18LA140

Nobody was injured.

A partial loss of engine power during an aerial application flight due to thermal damage to the 1st stage gas producer turbine nozzle and an irregular fuel spray pattern due to carbon buildup of the fuel nozzle. Contributing to the accident was maintenance personnel's inadequate inspection of the fuel nozzle.

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

Read the full NTSB narrative

The pilot of the helicopter was performing an aerial application flight in dark night conditions when he felt a vibration. The pilot pulled back on the cyclic control to stop the helicopter's forward movement and maintained this position for the remainder of the flight. Seconds later, the helicopter had descended to 40 ft above ground level (agl), and the low rotor rpm light indication illuminated, accompanied by multiple other warning lights. The helicopter continued to descend and impacted terrain upright. The main rotor blades severed the tail boom, the left skid dug into the ground, and the helicopter rolled over and came to rest on its right side. Examination of the helicopter revealed no anomalies with the flight control system. The engine inspection revealed thermal damage to the combustion liner and 1st stage gas turbine producer vanes, consistent with an irregular spray pattern from the fuel nozzle due to carbon buildup. Although the helicopter's weight at the time of the accident exceeded its published maximum gross weight by 100 lbs, whether this contributed to the helicopter's inability to maintain altitude following the loss of engine power was not determined. The engine logbook indicated that the fuel nozzles were inspected in accordance with the manufacturer's 100-hour inspection checklist about two years before the accident. Although a 100-hour inspection was completed about 4 months before the accident, the maintenance log entry did not specify the work completed, and whether the fuel nozzles were inspected at this time could not be determined; however, the carbon buildup on the fuel nozzles suggested long-term accumulation, and it is likely that maintenance personnel either omitted this inspection item or did not adequately inspect the fuel nozzles. Given the carbon accumulation of the fuel nozzle and signatures of irregular fuel spray, it is likely that the helicopter experienced a partial loss of engine power, which resulted in the subsequent descent into terrain.

Quoted verbatim from the NTSB record.