Aircraft Accident/Incident Report

Waitsburg, Washington 99361
Sunday, March 31, 1991 8:15 PST

NTSB Narrative Summary Released at Completion of Accident

WHILE THE PILOT WAS LOWERING THE COLLECTIVE PITCH AFTER LANDING TOUCHDOWN, THE MAIN ROTOR SEPARATED FROMT HE MAST. THE EXAMINATION REVEALED THE IMPROPER INSTALLATION OF THE MAST NUT AND LOCK WASHER WHEN THE MAIN ROTOR WAS INSTALLED.

NTSB Probable Cause Narrative

THE IMPROPER INSTALLATION OF THE MAIN ROTOR MAST NUT AND LOCK WASHER BY MAINTENANCE PERSONNEL WHICH RESULTED IN THE SEPARATION OF THE MAIN ROTOR SYSTEM.

Event Information

Type of Event Accident
Event Date 3/31/1991
Event Day of the Week Sunday
Time of Event 815
Event Time Zone Pacific Standard Time
Event City WAITSBURG
Event State WASHINGTON
Event Country --
Zipcode of the event site 99361
Event Date Year 1991
Event Date Month 3
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude
Event Location Longitude
Event Location Airport
Event Location Nearest Airport ID
Indicates whether the acc/inc occurred off or on an airport Off Airport/Airstrip
Distance from airport in statute miles 0
Degrees magnetic from airport 0
Airport Elevation --
Weather Briefing Completeness Unknown
Investigator's weather source Weather Observation Facility
Time of the weather observation 745 Pacific Standard Time
Direction of event from weather observation facility (degrees) 255
Weather Observation Facility ID PSC
Elevation of weather observation facility 406
Distance of event from weather observation facility (units?) 37
Time Zone of the weather observation PST
Lighting Conditions Day
Lowest Ceiling Height 0
Lowest Non-Ceiling Height 18000
Sky/Lowest/Cloud Conditions Scattered
Sky Condition for Lowest Ceiling None
Visibility Runway Visual Range (Feet) 0
Visibility Runway Visual Value (Statute Miles) 0
Visibility (Statute Miles) 50
Air Temperature at event time (in degrees celsius) 8
Dew Point at event time (in degress fahrenheit) 4
Wind Direction (degrees magnetic) 340
Variable Wind Indicator Unknown
Wind Speed (knots) 5
Wind Velocity Indicator Unknown
Wind Gust Indicator Unknown
Wind Gust (knots) 0
Altimeter Setting at event time (in. Hg) 30
Density Altitude (feet) 0
Intensity of Precipitation Unknown
METAR weather report --
Event Highest Injury None
On Ground, Fatal Injuries 0
On Ground, Minor Injuries 0
On Ground, Serious Injuries 0
Injury Total Fatal --
Injury Total Minor --
Injury Total None 1
Injury Total Serious --
Injury Total All --
Investigating Agency NTSB
NTSB Docket Number (internal use) 177
NTSB Notification Source --
NTSB Notification Date --
NTSB Notification Time 0
Fiche Number and/or location -used to find docket information 43260
Date of most recent change to record Dec 12 2000 9:35AM
User who most recently changed record dbo
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N38926
NTSB Number SEA91LA077
Missing Aircraft Indicator N
Federal Aviation Reg. Part Part 137: Agricultural
Type of Flight Plan filed None
Flight plan Was Activated? --
Damage Substantial
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name BELL
Aircraft Model BH-47G2A
Aircraft Series Identifier BH-47G2A
Aircraft Serial Number NAH 1957-1
Certified Max Gross Weight 2950
Aircraft Category Helicopter
Aircraft Registration Class U.S. Registered/U.S. Soil
Aircraft is a homebuilt? No
Flight Crew Seats --
Cabin Crew Seats --
Passenger Seats --
Total number of seats on the aircraft 3
Number of Engines 1
Fixed gear or retractable gear Fixed
Aircraft, Type of Last Inspection Unknown
Date of Last Inspection --
Airframe hours since last inspection 0
Airframe Hours --
ELT Installed No
ELT Activated No
ELT Aided Location of Event Site No
ELT Type --
Aircraft Owner Name WAITSBURG HELICOPTER SERVICE
Aircraft Owner Street Address P.O. BOX 658
Aircraft Owner City WAITSBURG
Aircraft Owner State WA
Aircraft Owner Country
Aircraft Owner Zipcode 99361
Operator is an individual? --
Operator Name WAITSBURG HELICOPTER SERVICE
Operator Same as Owner? Yes
Operator Is Doing Business As --
Operator Address Same as Owner? Yes
Operator Street Address P.O. BOX 658
Operator City WAITSBURG
Operator State WA
Operator Country
Operator Zip code 99361
Operator Code WPMG
Owner has at least one certificate Yes - certificate holder
Other Operator of large aircraft? No
Certified for Part 133 or 137 Operation Agriculture
Operator Certificate Number --
Indicates whether an air carrier operation was scheduled or not Unknown
Indicates Domestic or International Flight Unknown
Operator carrying Pax/Cargo/Mail Unknown
Type of Flying (Per_Bus / Primary) Aerial Application
Second Pilot on Board No
Departure Point Same as Event Yes
Departure Airport Code
Departure City
Departure State
Departure Country
Departure Time 0
Departure Time Zone
Destination Same as Local Flt dest & departure same, accident can occur anywhere
Destination Airport Code
Destination City
Destination State
Destination Country
Specific Phase of Flight Standing
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Jan 2 2001 10:35AM
User who most recently changed record dbo
Since inspection or accident --
Event Location Runway Number and Location 0
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --