NTSB Identification: CHI01LA259.
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Accident occurred Saturday, August 04, 2001 in Blooming Prairi, MN
Probable Cause Approval Date: 01/16/2003
Aircraft: Bell 47G-2, registration: N440TG
Injuries: 2 Uninjured.

NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The helicopter sustained substantial damage on impact with terrain during a forced landing following an in-flight loss of engine power while performing an operation under 14 CFR part 137. The pilot and passenger sustained no injuries. The pilot reported, "Observation executed at 75' AGL [above ground level] and below 20 mph. Engine loss of power. Autorotation to neighboring soybean field. Damage to aircraft. No Injuries. Aircraft had 20 gallons of fuel and no agricultural treatment products on board." The accident engine ran during a test run. The temperature was 29 degrees C and the dew point was 23 degrees C. At 1915, the calculated density altitude was 3,025 feet.
The temperature and dew point were plotted on the carburetor icing chart and their intersection fell in the serious icing - descent power area. The observation airspeed and altitude were plotted on height/velocity chart and their intersection falls in the avoid continuous operation area of the chart. The Bell 47G-2 flight manual stated, "PASSENGERS PROHIBITED DURING SPECIAL PURPOSE OPERATIONS. Persons other than minimum crew necessary for the purpose involved shall not be carried during special purpose operations in restricted category aircraft." FAA regulation section 91.313 stated' "Restricted category civil aircraft: Operating limitations. ... (d) No person may be carried on a restricted category civil aircraft unless that person- (1) Is a flight crewmember; (2) Is a flight crewmember trainee; (3) Performs an essential function in connection with a special purpose operation for which the aircraft is certificated; or (4) Is necessary to accomplish the work activity directly associated with that special purpose."

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The reported loss of engine power for undetermined reasons during a the cruise portion of a CFR part 137 observation, and the pilot not following the height/velocity charts data.

Full narrative available

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