Bell OH-58A N158TR

Summary

On 21 November 2023 at about 04:05 local time, a Bell OH-58A registered N158TR was involved in an accident near Brawley, 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

21 November 2023 at 04:05

Classification

Accident

Location

Brawley, California, United States

Nearest airport

Brawley Municipal (KBWC)

Coordinates

33.0020, -115.4670

Aircraft

Bell OH-58A

Registration

N158TR

Category

Helicopter

Year built

1971

Engines

1

Operator

Not recorded

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Night

NTSB number

WPR24LA041

Nobody was injured.

A total loss of engine power due to the failure of the No. 8 bearing and the subsequent failure of the scavenge oil pump.

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

Read the full NTSB narrative

The pilot was conducting agricultural operations at night and had just departed from a company loading area. About 150 ft above ground level (agl), the pilot experienced a sudden power surge, abnormal engine noise, and vibration. The pilot believed that engine failure was imminent and turned back toward his point of departure. Engine power decayed, and the pilot bled off rotor rpm to maneuver over terrain toward flat ground. The helicopter landed hard, entered a pylon whirl condition, and the main rotor hub assembly separated from the main rotor mast. Postaccident examination of the airframe revealed no evidence of preaccident mechanical malfunction or failure. However, postaccident examination revealed a sheen of oil beneath the engine and that the engine’s compressor (N1) and power turbine (N2) systems were seized. Further examination of the engine revealed multiple failed bearings, failed drives, and fractures within the turbine scavenge oil pump assembly. The engine had been installed on the helicopter about 10 flight hours before the accident. Based on metallurgical analysis of the engine components, the No. 8 bearing likely failed and shed debris to the oil pump, which bound the first level oil pump gears and led a gear tooth to fracture and the pump driveshaft to fail. Subsequently, the engine was starved of oil and lost all power. The cause of the bearing failure could not be determined.

Quoted verbatim from the NTSB record.