Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Yuma, Arizona 85364
Sunday, September 10, 1995 9:20 MST
NTSB Narrative Summary Released at Completion of Accident
The pilot said he was en route to spray a field at 150 feet agl when he heard a loud bang, and a fluttering vibration began through the airframe. The helicopter did not respond to anti-torque control inputs and began to spin. The pilot lowered the collective and reduced throttle to control the spin and the helicopter landed hard. The aft left engine mount frame was found separated from the fuselage frame attachment clevis ears. The clevis ears were found fractured. The engine was displaced forward and to the right and was impinging on the collective servo. The tail rotor short shaft was pulled out and disconnected. The components were sent for metallurgical examination. The clevis ear fractures revealed features indicative of fatigue cracking emanating from multiple origins on the forward and aft faces. The fractures exhibited severe oxidation damage with rust colored deposits evident externally. The metal in the frame and clevis ears was correct for the material specification in the manufacturing drawings. During assembly a washer is welded circumferentially around the outside diameter to the inboard side of each clevis ear. Microhardness testing of the welds, heat affected zones (HAZ), and the base metal of the clevis ears and corresponding washers revealed that the tensile strength of the HAZ adjacent to the fracture of the forward clevis ear was significantly higher than the strength of the weld and the base metal. An annual inspection was accomplished on the helicopter 77 hours prior to the accident and the area of the cracks are the subject of a daily inspection requirement.
NTSB Probable Cause Narrative
the failure of the pilot and company maintenance personnel to detect a crack in the clevis ears during the required daily inspection and the recent annual inspection. A factor in the accident was the improper welding and stress relief procedure used to assemble the components, which induced high residual stresses in the clevis ears and led to fatigue cracking of the part.
Event Information
| Type of Event | Accident |
| Event Date | 9/10/1995 |
| Event Day of the Week | Sunday |
| Time of Event | 920 |
| Event Time Zone | Mountain Standard Time |
| Event City | YUMA |
| Event State | ARIZONA |
| Event Country | -- |
| Zipcode of the event site | 85364 |
| Event Date Year | 1995 |
| Event Date Month | 9 |
| 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 | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | Unknown |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 856 Mountain Standard Time |
| Direction of event from weather observation facility (degrees) | 280 |
| Weather Observation Facility ID | YUM |
| Elevation of weather observation facility | 213 |
| Distance of event from weather observation facility (units?) | 18 |
| Time Zone of the weather observation | MST |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 0 |
| Lowest Non-Ceiling Height | 15000 |
| 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) | 10 |
| Air Temperature at event time (in degrees celsius) | 31 |
| Dew Point at event time (in degress fahrenheit) | 9 |
| Wind Direction (degrees magnetic) | 0 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 0 |
| Wind Velocity Indicator | Calm |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | 0 |
| Altimeter Setting at event time (in. Hg) | 29 |
| Density Altitude (feet) | -- |
| 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) | 1933 |
| NTSB Notification Source | -- |
| NTSB Notification Date | Sep 10 1995 12:00AM |
| NTSB Notification Time | 940 |
| Fiche Number and/or location -used to find docket information | IMAGE |
| Date of most recent change to record | Dec 7 2000 4:35PM |
| User who most recently changed record | dbo |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N7942J |
| NTSB Number | LAX95LA331 |
| 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 | 47G-3B2 |
| Aircraft Series Identifier | 47G-3B2 |
| Aircraft Serial Number | 6804 |
| 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 | Annual |
| Date of Last Inspection | Jun 20 1995 12:00AM |
| Airframe hours since last inspection | 100 |
| Airframe Hours | -- |
| ELT Installed | No |
| ELT Activated | Unknown |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | SUNDOWN HELICOPTERS, INC. |
| Aircraft Owner Street Address | 2736 OLIVEWOOD LANE |
| Aircraft Owner City | YUMA |
| Aircraft Owner State | AZ |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | 85364 |
| Operator is an individual? | -- |
| Operator Name | |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | |
| Operator City | |
| Operator State | |
| Operator Country | |
| Operator Zip code | |
| Operator Code | SZDG |
| 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 | YUM |
| Departure City | |
| Departure State | |
| Departure Country | |
| Departure Time | 850 |
| Departure Time Zone | MST |
| 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 | Cruise |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jan 2 2001 10:34AM |
| 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 | -- |