Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
El Dara, Illinois 62356
Sunday, August 28, 2005 9:15 CDT
NTSB Narrative Summary Released at Completion of Accident
The experimental amatueur-built helicopter collided with trees and terrain following an in-flight separation of a tail rotor blade. Witnesses reported seeing the helicopter spinning prior to it contacting the terrain. The helicopter was involved in a hard landing in 2004 after which the main rotor blades and tail rotor assembly including the spindle and blades were replaced. According to the pilot's friend, they balanced the new tail rotor blades after they were installed, but the blades continued to run "rough." The pilot voiced these concerns to the manufacturer and the manufacturer sent replacement tail rotor blades to the pilot. According to the manufacturer and the pilot's friend, the helicopter was running fine after the replacement blades were installed. Examination of the wreckage revealed all major components of the helicopter were located at the main wreckage site except for one of the tail rotor blades and the respective outboard 2 inches of the tail rotor spindle which were not located. The tail rotor spindle contained two integral rods, which extended out in opposite directions. The length of each rod was manufactured with sections of consecutively reduced diameter. A metallurgical examination of the spindle revealed a fatigue failure was present, which initiated at the fillet radius between the sections where the rod steps down from 0.812-inch diameter to 0.750-inch diameter. The relief radius in this area was rough and irregular. The manufacturer provided the engineering drawings for the tail rotor spindle. Drawing #15 did not specify a relief radius for the transition area between the .812-inch and .750-inch diameter sections. On September 14, 2005, Canadian Home Rotors (CHR), provided a revised drawing #15 requiring a 0.0156-inch relief radius between the 0.812-inch and 0.750-inch diameter sections. The relief radius measured at the failure was approximately 0.0073-inch.
NTSB Probable Cause Narrative
The manufacturer failed to specify a relief radius on the tail rotor spindle drawings, which resulted in the spindle being manufactured with an inadequate relief radius at the point of fatigue failure.
Event Information
| Type of Event | Accident |
| Event Date | 8/28/2005 |
| Event Day of the Week | Sunday |
| Time of Event | 915 |
| Event Time Zone | Central Daylight Time |
| Event City | El Dara |
| Event State | ILLINOIS |
| Event Country | -- |
| Zipcode of the event site | 62356 |
| Event Date Year | 2005 |
| Event Date Month | 8 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 393820N |
| Event Location Longitude | 0904643W |
| 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 | Weather Observation Facility |
| Time of the weather observation | 854 Central Daylight Time |
| Direction of event from weather observation facility (degrees) | 340 |
| Weather Observation Facility ID | UIN |
| Elevation of weather observation facility | 769 |
| Distance of event from weather observation facility (units?) | 22 |
| Time Zone of the weather observation | CDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | 11000 |
| Sky/Lowest/Cloud Conditions | Few |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 10 |
| Air Temperature at event time (in degrees celsius) | 21 |
| Dew Point at event time (in degress fahrenheit) | 17 |
| Wind Direction (degrees magnetic) | 230 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 4 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 29.89 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | Fatal |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | 1 |
| Injury Total Minor | -- |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | 1 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 19630 |
| NTSB Notification Source | FAA |
| NTSB Notification Date | Aug 28 2005 12:00AM |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | May 30 2006 1:54PM |
| User who most recently changed record | NTSB\JOHB |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | Springfield, IL FSDO |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N9094P |
| NTSB Number | CHI05LA243 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Destroyed |
| Aircraft Fire | Ground |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Allensworth |
| Aircraft Model | Baby Belle |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 2053 |
| Certified Max Gross Weight | 1450 |
| Aircraft Category | Helicopter |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | Yes |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 2 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | -- |
| Date of Last Inspection | -- |
| Airframe hours since last inspection | -- |
| Airframe Hours | -- |
| ELT Installed | No |
| ELT Activated | -- |
| ELT Aided Location of Event Site | -- |
| ELT Type | -- |
| Aircraft Owner Name | David D. Allensworth |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | New Canton |
| Aircraft Owner State | IL |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 62356 |
| Operator is an individual? | No |
| 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 | None |
| Other Operator of large aircraft? | -- |
| Certified for Part 133 or 137 Operation | -- |
| 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) | Personal |
| Second Pilot on Board | No |
| Departure Point Same as Event | No |
| Departure Airport Code | -- |
| Departure City | New Canton |
| Departure State | IL |
| Departure Country | USA |
| Departure Time | 900 |
| Departure Time Zone | CDT |
| Destination Same as Local Flt | dest & departure same, accident can occur anywhere |
| Destination Airport Code | -- |
| Destination City | New Canton |
| Destination State | IL |
| Destination Country | USA |
| Specific Phase of Flight | Emergency descent/landing |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Feb 16 2006 1:03PM |
| User who most recently changed record | SULP |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | NA |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |