Bell 206 N10CV accident near Rio Grande, Puerto Rico

Probable cause

A total loss of engine power due to oil exhaustion, which resulted in an uncontrolled descent and hard landing.

NTSB analysis

The private pilot and three passengers were on a personal local flight. A passenger stated that the first few minutes of the flight were normal, but he then felt what he described as "a pull from the ground," and the helicopter started to descend. He reported hearing a "beep beep" sound, which is consistent with an engine out warning. The passenger reported that the pilot subsequently attempted to land on a road, but the passenger felt the helicopter "just fall down and crash."

During the postaccident examination of the helicopter, 9.5 ounces of engine oil were drained from the oil supply tank, and 6 ounces of engine oil, which contained some metallic debris were drained from the accessory gearbox; however, no significant anomalies were noted following testing of the drained oil.

Engine bearings Nos. 2.5, 6, and 8 did not contain any oil. Noted damage to all of the main bearings was consistent with thermal distress. Slight oil streaking was noted on both sides of the aft fuselage; the source of the oil could not be determined and most likely occurred postaccident.

Material loss of the No. 2 bearing due to a loss of oil resulted in a loss of axial support of the compressor impeller by the No. 2 bearing, allowing forward axial movement of the compressor impeller from its normal position. The compressor impeller eventually contacted the compressor shroud, resulting in a sudden decrease in N1 rpm and a loss of engine power.

The passengers account of the pilot's behavior did not suggest that the pilot was confused or had difficulty in responding to the inflight emergency; therefore, it is unlikely that any of the pilot's known medical conditions or use of medications contributed to the accident.

Text from the NTSB. Open the NTSB docket for ERA18LA183 for the full record.