Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Yuma, Arizona 85365
Friday, November 23, 2007 19:30 MST
NTSB Narrative Summary Released at Completion of Accident
While conducting an aerial application flight, the pilot reported that he was initiating a turn over a set of power lines at an altitude of about 60 feet above ground level (agl). As the helicopter crossed over a series of power lines, the pilot heard a "loud pop" and felt an extreme vibration. The pilot maneuvered the helicopter away from the power lines and initiated a forced landing to an open field. He reported that control of the helicopter was "marginal" as the helicopter descended. Shortly before touchdown, the helicopter began to drift (un commanded) to the left and the pilot lowered the collective. The helicopter touched down hard, pivoted to the left and rolled over onto its right side. Post accident examination of the helicopter revealed that a control rotor had separated from the rotor system. The separated control rotor was found in the area where the vibration started. Examination of the control rotor assembly revealed the tubular spar of the blue control rotor was circumferentially fractured at the outboard cuff bolt location. Magnified examinations of the outboard fracture surfaces revealed surface features consistent with fatigue progression in two fronts around the spar. Fatigue initiation locations were identified on opposite sides of one of the outboard bolt holes in the spar. One fatigue origin was identified on the bore surface of the bolt hole and the other was mechanically damaged preventing determination of its exact location. The bore surface was rough and no obvious corrosion was noted in the hole. From the bolt hole the fatigue propagated almost entirely around the spar with very small overstress regions connecting the fatigue to the opposite bolt hole in the spar. No corrosion was noted in the originating bolt hole, however, the exterior surface of the spar exhibited wide spread pitting corrosion and fretting on the faying surfaces with the control rotor cuff. Additional localized corrosion was noted on the interior faying surface of the cuff. Maintenance records indicated that the most recent 100-hour inspection was conducted about 77 hours prior to the accident. The logbook entry associated with the inspection indicated that Airworthiness Directive AD 97-10-16 had been complied with. AD 97-10-16 (effective date 6/26/97) states, in part,: "To prevent separation of the control rotor blade assembly and subsequent loss of control of the helicopter, accomplish the following: (a) Within the next 100 hours time-in-service (TIS) after the effective date of the AD, unless previously accomplished within the last 100 hours TIS, and thereafter at intervals not to exceed 100 hours TIS from the date of the last inspection, or at the next annual inspection, whichever occurs first, inspect the blade spar tube and cuff for corrosion or cracks, or elongation, corrosion, burrs, pitting or fretting of the bolt holes, and repair, as necessary..."
NTSB Probable Cause Narrative
Fatigue fracture of the control rotor blade spar and failure of maintenance personnel to follow maintenance directives.
Event Information
| Type of Event | Accident |
| Event Date | 11/23/2007 |
| Event Day of the Week | Friday |
| Time of Event | 1930 |
| Event Time Zone | Mountain Standard Time |
| Event City | Yuma |
| Event State | ARIZONA |
| Event Country | -- |
| Zipcode of the event site | 85365 |
| Event Date Year | 2007 |
| Event Date Month | 11 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 323923N |
| Event Location Longitude | 1143621W |
| 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 | -- |
| Investigator's weather source | Pilot |
| Time of the weather observation | |
| Direction of event from weather observation facility (degrees) | -- |
| Weather Observation Facility ID | -- |
| Elevation of weather observation facility | -- |
| Distance of event from weather observation facility (units?) | -- |
| Time Zone of the weather observation | -- |
| Lighting Conditions | Night |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | -- |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | -- |
| Air Temperature at event time (in degrees celsius) | 15 |
| Dew Point at event time (in degress fahrenheit) | -- |
| Wind Direction (degrees magnetic) | 315 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 3 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | -- |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | None |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | 1 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 23393 |
| NTSB Notification Source | FAA-ROC |
| NTSB Notification Date | Nov 23 2007 12:00AM |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Apr 30 2008 1:28PM |
| User who most recently changed record | NTSB\johb |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | Scottsdale, Arizona |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N104EA |
| NTSB Number | SEA08LA038 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 137: Agricultural |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | No |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Hiller |
| Aircraft Model | UH-12E |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | HA3028 |
| Certified Max Gross Weight | 3100 |
| Aircraft Category | Helicopter |
| Aircraft Registration Class | -- |
| 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 | AAIP |
| Date of Last Inspection | Oct 1 2007 12:00AM |
| Airframe hours since last inspection | -- |
| Airframe Hours | 8251.5 |
| ELT Installed | No |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | Tri-Rotor Spray & Chemical |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | Ulysses |
| Aircraft Owner State | AZ |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 67880 |
| Operator is an individual? | Yes |
| 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 | -- |
| Owner has at least one certificate | -- |
| Other Operator of large aircraft? | -- |
| Certified for Part 133 or 137 Operation | Agriculture |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | -- |
| Indicates Domestic or International Flight | -- |
| Operator carrying Pax/Cargo/Mail | -- |
| Type of Flying (Per_Bus / Primary) | Aerial Application |
| Second Pilot on Board | No |
| Departure Point Same as Event | No |
| Departure Airport Code | -- |
| Departure City | Yuma |
| Departure State | AZ |
| Departure Country | USA |
| Departure Time | 1920 |
| Departure Time Zone | PST |
| 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 | Landing |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Mar 31 2008 7:22PM |
| User who most recently changed record | STAM |
| Since inspection or accident | Last Inspection |
| Event Location Runway Number and Location | NA |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |