Cobb EXEC 90 N89678

Summary

On 9 February 1993 at about 21:55 local time, a Cobb EXEC 90 registered N89678, operated by Cobb International, Inc., was involved in an accident near Chandler, Arizona, 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

9 February 1993 at 21:55

Classification

Accident

Location

Chandler, Arizona, United States

Coordinates

33.2391, -111.7791

Aircraft

Cobb EXEC 90

Registration

N89678

Category

Helicopter

Engines

1

Operator

Cobb International, Inc.

Operating rule

Part 91: General Aviation

Purpose of flight

Other Work Use

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX93LA111

Nobody was injured.

THE MANUFACTURER'S INADEQUATE QUALITY CONTROL WHICH RESULTED IN THE FATIGUE OF THE VALVE STEM. THE SOFT TERRAIN CONTRIBUTED TO THIS ACCIDENT.

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

Read the full NTSB narrative

THE HELICOPTER'S ENGINE FAILED WHILE ON THE CROSSWIND LEG. THE SURROUNDING TERRAIN WAS CONGESTED FORCING THE PILOT TO LAND IN AN AREA WHICH WAS DOWNWIND. THE HELICOPTER NOSED DOWN ON LANDING IN THE SOFT TERRAIN. EXAMINATION OF THE ENGINE DISCLOSED THAT AN INTAKE VALVE FAILED AND LODGED IN THE PISTON. METALLURGICAL EXAMINATION REVEALED THAT THE VALVE STEM FAILED IN FATIGUE. THE FATIGUE WAS PRECIPITATED BY THE MANUFACTURER'S IMPROPER QUALITY CONTROL WHICH FAILED TO ASSURE THAT THE VALVE WAS GROUND BEFORE IT WAS PLATED.

Quoted verbatim from the NTSB record.