Hiller UH 12E N107HA

Summary

On 26 July 2014 at about 19:45 local time, a Hiller UH 12E registered N107HA, operated by Summit Helicopters Inc, was involved in an accident near Wadesboro, North Carolina, 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

26 July 2014 at 19:45

Classification

Accident

Location

Wadesboro, North Carolina, United States

Coordinates

34.8264, -80.2414

Aircraft

Hiller UH 12E

Registration

N107HA

Category

Helicopter

Year built

1974

Engines

1

Operator

Summit Helicopters Inc

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Wadesboro → Wadesboro

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA14LA361

Nobody was injured.

A partial loss of engine power due to the failure of the No. 2 engine accessory gearbox bearing for reasons that could not be determined based on the available information.

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

Read the full NTSB narrative

The airline transport pilot was conducting an aerial application flight in the helicopter. About 75 ft above ground level, the pilot heard three engine compressor stalls, which were followed by a partial loss of engine power. During the ensuing forced landing to a nearby road, the helicopter rolled over into a drainage ditch and came to rest on its right side. Examination of the engine revealed that the accessory gearbox No. 2 bearing had degraded and fractured. The bearing displayed evidence of heat damage associated with its degradation. The cage of the bearing revealed fatigue fractures with multiple origins, indicative of relatively high-stress concentrations to the bearing. The cage fractures were likely secondary failures following the initial degradation of the bearing. The bearing balls were black in appearance. In addition, they were undersized when compared to engineering drawing requirements and displayed signatures consistent with material loss, likely from wear. Considering that the engine had accumulated only about 92 hours since the gearbox was installed following an overhaul, it was possible that the bearings experienced an abnormal load. The cause of the abnormal load could have been due to installation error, an alignment issue from a previous hard landing that was noted in the gearbox maintenance records, or from insufficient lubrication within the gearbox assembly. However, the investigation could not determine which of these factors, if any, caused the failure of the No. 2 bearing and resulted in the partial loss of engine power.  

Quoted verbatim from the NTSB record.