Bell 206L N970CC

Summary

On 27 February 1995 at about 14:15 local time, a Bell 206L registered N970CC was involved in an accident near Maryland Hts, Missouri, United States. 5 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

27 February 1995 at 14:15

Classification

Accident

Location

Maryland Hts, Missouri, United States

Coordinates

38.7209, -90.4698

Aircraft

Bell 206L

Registration

N970CC

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Business

Phase of flight

Not recorded

Route

Unknown → Jefferson

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CHI95LA093

Nobody was injured.

FATIGUE FAILURE OF TWO ATTACHMENT BOLTS THAT CONNECTED THE DRIVESHAFT TO THE GEARED PORTION OF A DRIVESHAFT COUPLING. FACTORS RELATING TO THE ACCIDENT WERE: INADEQUATE MAINTENANCE, UNEVEN TERRAIN IN THE TOUCHDOWN AREA FOR THE FORCED LANDING, AND THE UNFAVORABLE HEIGHT/VELOCITY SITUATION OF THE HELICOPTER WHEN THE DRIVESHAFT DISCONNECT OCCURRED.

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

Read the full NTSB narrative

THE PILOT OF A TURBINE POWERED HELICOPTER SAID HE BEGAN A HOVER ABOUT THREE FEET ABOVE THE GROUND, TURNED THE HELICOPTER INTO THE WIND, AND INITIATED A TAKEOFF. ACCORDING TO WITNESSES, THE HELICOPTER HAD STARTED TO MOVE FORWARD AND HAD ATTAINED AN ALTITUDE OF ABOUT 25 FEET, WHEN THEY HEARD A CHANGE IN THE SOUND OF THE ENGINE. THE PILOT STATED 'AS POWER WAS BROUGHT IN, A LOUD METALLIC TYPE POP WAS HEARD.' HE SAID THE HELICOPTER YAWED LEFT AFTER THE 'POP' WAS HEARD, AND THAT IT DID NOT RESPOND TO CONTROL INPUTS. THE HELICOPTER FLEW OVER AN EMBANKMENT, AND ITS ROTOR BLADES STRUCK THE SIDE OF THE EMBANKMENT. AFTER THE BLADE STRIKE, THE HELICOPTER ROLLED OVER ONTO ITS LEFT SIDE, THEN ON ITS RIGHT SIDE AND CAME TO REST. EXAMINATION OF THE HELICOPTER AND ITS COMPONENTS REVEALED THE ATTACHMENT BOLTS THAT CONNECTED THE DRIVESHAFT TO THE GEARED PORTION OF THE DRIVESHAFT COUPLING HAD FAILED. METALLURGICAL EXAMINATION REVEALED THAT TWO OF THE BOLTS HAD FAILED FROM FATIGUE, THE OTHER TWO BOLTS HAD EVIDENCE OF OVERLOAD FAILURE. ALSO, AFTER DISASSEMBLY, A TENSION (CENTERING) SPRING WAS DISCOVERED TO BE MISSING FROM THE TRANSMISSION END OF THE DRIVESHAFT (WHICH WOULD HAVE ALLOWED THE BOLT HEADS TO CONTACT THE GREASE RETAINING PLATE). THE LAST ANNUAL INSPECTION OF THE HELICOPTER AND ENGINE WAS ON 11/3/93.

Quoted verbatim from the NTSB record.