Sikorsky SK-58 N58WH

Summary

On 22 July 1991 at about 04:40 local time, a Sikorsky SK-58 registered N58WH, operated by Associated Helicopter Services, was involved in an accident near Daggett, California, United States. 3 people were 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

22 July 1991 at 04:40

Classification

Accident

Location

Daggett, California, United States

Coordinates

34.8592, -116.8109

Aircraft

Sikorsky SK-58

Registration

N58WH

Category

Helicopter

Engines

1

Operator

Associated Helicopter Services

Operating rule

Part 133: Rotorcraft Ext. Load

Purpose of flight

Other Work Use

Phase of flight

Not recorded

Route

Barstow → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Night/Dark

NTSB number

LAX91LA320

Nobody was injured.

THE FAILURE OF AN ENGINE CONNECTING ROD CAUSING A REDUCTION OF ENGINE POWER TO THE POINT WHERE LEVEL FLIGHT COULD NOT BE MAINTAINED. A FACTOR IN THE ACCIDENT WAS THE DARK NIGHT CONDITIONS WHICH RESTRICTED THE PILOT'S ABILITY TO SELECT THE BEST LANDING SITE.

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

Read the full NTSB narrative

WHILE RETURNING FROM AN EXTERNAL LOAD OPERATION, THE HELICOPTER'S ENGINE STARTED VIBRATING AND THEN STARTED BACK FIRING. THE PILOT REPORTED HEARING A LOUD 'BANG' AND THEN NOTED A DECREASE IN ENGINE POWER. HE PERFORMED NECESSARY EMERGENCY PROCEDURES AND ENTERED AN AUTOROTATION. HE SAID THAT HE TOUCHED DOWN WITH SOME FORWARD SPEED. THE HELICOPTER HIT A DIRT BERM. THE ROTOR BLADES CONTACTED THE GROUND AND THE AIRCRAFT ROLLED OVER. AN ENGINE TEARDOWN WAS PERFORMED UNDER THE SUPERVISION OF AN FAA AIRWORTHINESS INSPECTOR. A BROKEN ROD WAS FOUND DURING THE TEARDOWN. THE TEARDOWN WAS TERMINATED AT THAT POINT AND THE REASON FOR THE BROKEN ROD WAS NOT DETERMINED.

Quoted verbatim from the NTSB record.