Bell UH-1H N911SZ

Summary

On 17 July 2022 at about 01:20 local time, a Bell UH-1H registered N911SZ, operated by Bernalillo County Sheriffs Department, was involved in an accident near Chapelle, New Mexico, United States. 4 people were on board and 4 died. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

17 July 2022 at 01:20

Classification

Accident

Location

Chapelle, New Mexico, United States

Coordinates

35.3800, -105.2374

Aircraft

Bell UH-1H

Registration

N911SZ

Category

Helicopter

Year built

1970

Engines

1

Operator

Bernalillo County Sheriffs Department

Operating rule

Public Use

Purpose of flight

Positioning

Phase of flight

Not recorded

Route

Las Vegas → Albuquerque

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

CEN22FA317

4 people died.

The total loss of engine power due to the fatigue failure of the starter-generator input (zerol) gear which failed due to poor maintenance. Contributing to the accident was the unsuccessful autorotation complicated by the setting sun and high density altitude.

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

Read the full NTSB narrative

The pilot of the helicopter, two tactical flight observers, and a rescue specialist were returning to their home airport after conducting firefighting operations. While in a west-bound cruise flight about 500 to 600 ft about ground level (agl), the helicopter entered a descent that rapidly increased to over 5,000 ft per minute, and impacted terrain in a tail-low attitude. The helicopter was destroyed during the impact with terrain. Examination of the engine revealed that the starter-generator input (zerol) gear failed due to fatigue. This failure led to the starter-generator driveshaft shearing, N1 accessory gearbox seizure, and a total loss of engine power. An examination of the remaining helicopter systems revealed no mechanical anomalies that would have precluded normal operations. About 17 flight hours before the accident, an engine chip event occurred, and a small piece of ferrous metal was found on the magnetic chip plug. Following the chip event the oil system was drained and flushed and the filter elements were removed, cleaned, and reinstalled. No further engine chip lights were reported after the engine chip event. The chip and oil sample were shipped to a lab for analysis. The results of the lab analysis were not used by the operator to troubleshoot the reason for the chip event. Had the operator conducted an analysis, they could have potentially identified the deteriorating component and impending failure. The helicopter’s low altitude (500 to 600 ft agl) during the return leg made the transition from powered flight to autorotation after an unexpected loss of engine power more time critical. The high density altitude conditions, combined with flight directly into the setting sun, may have contributed to the unsuccessful autorotation following the total loss of engine power.

Quoted verbatim from the NTSB record.