Aviation Accident Summaries

Aviation Accident Summary DEN92FA034

FORT COLLINS, CO, USA

Aircraft #1

N99TV

BELL 206L-3

Analysis

THE HELICOPTER WAS BEING FLOWN TO A MAINTENANCE FACILITY TO CORRECT A 'ROTOR VIBRATION' THAT HAD BEEN DETECTED BY THE PILOT. WHILE IN CRUISE FLIGHT OVER A RESERVOIR, A LOSS OF ENGINE POWER OCCURRED, WHEN THE #2-1/2 BEARING FAILED DUE TO OIL STARVATION. THE OIL STARVATION RESULTED FROM AN OBSTRUCTION IN THE BEARING OIL FEED TUBE BY A PARTICLE OF FOREIGN MATERIAL. THERE WAS EVIDENCE THE MATERIAL WAS INTRODUCED INTO THE SYSTEM DURING OVERHAUL, ABOUT 9 FLIGHT HOURS BEFORE THE ACCIDENT. THE PILOT MADE AN AUTOROTATION THROUGH DENSE FOG TO THE SURFACE OF THE RESERVOIR, WHICH CONTAINED PATCHES OF ICE. THE HELICOPTER SANK IN 190 FT OF WATER. WATER TEMPERATURE WAS 30 DEG F, AIR TEMPERATURE WAS 34 DEG, AND WIND WAS 170 DEG AT 8 KTS. ACCORDING TO AVAILABLE INFORMATION, USEFUL CONSCIOUS TIME UNDER THESE CONDITIONS WOULD HAVE BEEN ABOUT 15 MIN. THE FIRST RESCUE PERSONNEL REACHED THE PILOT APPROXIMATELY 45 MIN FOLLOWING THE ACCIDENT. THE PILOT WAS THE ONLY PERSON ON THE SURFACE AT THAT TIME.

Probable Cause and Findings

FAILURE OF THE NUMBER 2-1/2 BEARING DUE TO AN OBSTRUCTION OF A BEARING OIL FEED TUBE BY FOREIGN MATERIAL. FACTORS RELATED TO THE ACCIDENT WERE: IMPROPER MAINTENANCE DURING ENGINE OVERHAUL, AND WEATHER/TERRAIN/WATER CONDITIONS IN THE EMERGENCY LANDING AREA.

 

Source: NTSB Aviation Accident Database

Get all the details on your iPhone or iPad with:

Aviation Accidents App

In-Depth Access to Aviation Accident Reports