Bell 412 N524EH

Summary

On 6 May 1989 at about 20:38 local time, a Bell 412 registered N524EH was involved in an accident near Girdwood, Alaska, United States. 2 people were on board and 2 had minor injuries. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

6 May 1989 at 20:38

Classification

Accident

Location

Girdwood, Alaska, United States

Coordinates

60.8998, -148.9103

Aircraft

Bell 412

Registration

N524EH

Category

Helicopter

Engines

2

Operator

Not recorded

Operating rule

Part 135: Air Taxi & Commuter

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Valdez → Anchorage

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

ANC89FA069

2 people had minor injuries.

A MAIN ROTOR FLIGHT CONTROL BOLT (PART NUMBER 20-057-6-38D) CAME OUT OF ITS ROD END BEARING WHILE IN FLIGHT DUE TO THE BOLT BEING IMPROPERLY TORQUED DURING MAINTENANCE.

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

Read the full NTSB narrative

WHILE IFR AT 10,000 FEET OVER MOUNTAINOUS TERRAIN, THE HELCIOPTER EXPERIENCED VIOLENT VERTICAL VIBRATIONS, WHICH CONTINUED UNTIL THE CRASH-LANDING ABOUT FIVE MINUTES LATER. ON BOARD WEATHER RADAR WAS USED TO GUIDE THE HELICOPTER AROUND THE MOUNTAIN TOPS, WHICH WERE IN THE CLOUDS. AT ABOUT 200 FEET ABOVE THE GROUND, THE HELICOPTER CAUGHT FIRE, TAIL ROTOR CONTROL WAS LOST, BOTH ENGINES QUIT, AND CYCLIC CONTROL BECAME UNRESPONSIVE. THE HELICOPTER WAS DESTROYED BY POST-CRASH FIRE. ABOUT ONE HOUR OF FLT TIME EARLIER, THE HELICOPTER HAD UNDERGONE AN INSPECTION, DURING WHICH THE MAIN ROTOR FLIGHT CONTROL SYSTEM BOLTS HAD BEEN RETORQUED. ALL BUT ONE OF THESE BOLTS WERE FOUND IN THE WRECKAGE. HOWEVER, THE ROD END FOR THE MISSING BOLT WAS FOUND.

Quoted verbatim from the NTSB record.