Individually Owned: 150,657
Corporate Owned: 137,281
Boise Air Terminal/Gowen Field Airport
Aircraft Accident/Incident Report
Boise, Idaho 83705
Monday, May 15, 2006 15:35 MDT
NTSB Narrative Summary Released at Completion of Accident
During an instructional flight, in which a practice autorotation was to be demonstrated, the instructor pilot instructed the student to reduce the throttle to idle to simulate an engine failure at altitude. During the course of the maneuver and after the throttle had been reduced to idle the instructor became aware that the engine had failed. An autorotation was completed to the ground into the wind to a grass field with a slight up slope, which resulted in the helicopter sliding backwards approximately 15 feet before the tail boom, which flexed up was impacted by the main rotor. The helicopter suffered damage to the tail boom, all three main rotor blades, and the tail rotor drive shaft. A subsequent engine run, which was overseen by two FAA inspectors, revealed no anomalies which would have precluded normal operations. The inspectors did note that while the idle rpm and idle mixture were adjusted poorly for altitude and temperature, this did not result in the loss of engine power; the instructor pilot's failure to follow the cautions in the helicopter's flight manual did result in the loss of power.
NTSB Probable Cause Narrative
The reduction of the throttle to idle at a high density altitude during a practice autorotation, which resulted in the engine stoppage. Factors contributing to the accident included the instructor pilot's improper planning by not adhering to the flight manual's warning to avoid reducing the throttle to the idle position at high density altitudes, and the uneven terrain.
Event Information
| Type of Event | Accident |
| Event Date | 5/15/2006 |
| Event Day of the Week | Monday |
| Time of Event | 1535 |
| Event Time Zone | Mountain Daylight Time |
| Event City | Boise |
| Event State | IDAHO |
| Event Country | -- |
| Zipcode of the event site | 83705 |
| Event Date Year | 2006 |
| Event Date Month | 5 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 433157N |
| Event Location Longitude | 1161346W |
| Event Location Airport | Boise Air Terminal/Gowen Field |
| Event Location Nearest Airport ID | BOI |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | 2 |
| Degrees magnetic from airport | -- |
| Airport Elevation | 2871 |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 1553 Mountain Daylight Time |
| Direction of event from weather observation facility (degrees) | 340 |
| Weather Observation Facility ID | BOI |
| Elevation of weather observation facility | 2871 |
| Distance of event from weather observation facility (units?) | 2 |
| Time Zone of the weather observation | MDT |
| Lighting Conditions | Day |
| 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) | 10 |
| Air Temperature at event time (in degrees celsius) | 33 |
| Dew Point at event time (in degress fahrenheit) | -1 |
| Wind Direction (degrees magnetic) | 140 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 13 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 30.04 |
| 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 | 2 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 20403 |
| NTSB Notification Source | Regional Operations Center |
| NTSB Notification Date | May 15 2006 12:00AM |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Oct 3 2006 2:46PM |
| User who most recently changed record | NTSB\JOHB |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | Boise, Idaho |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N2096W |
| NTSB Number | SEA06LA096 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Schweizer |
| Aircraft Model | 269C |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | S 1865 |
| Certified Max Gross Weight | 2050 |
| 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 | 2 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | Annual |
| Date of Last Inspection | May 1 2006 12:00AM |
| Airframe hours since last inspection | 15 |
| Airframe Hours | 978 |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | Aviation Specialties Unlimited |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | Boise |
| Aircraft Owner State | ID |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 83705 |
| 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 | UABS |
| 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) | Instructional |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | No |
| Departure Airport Code | BOI |
| Departure City | Boise |
| Departure State | ID |
| Departure Country | USA |
| Departure Time | 1415 |
| Departure Time Zone | MDT |
| 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 - flare/touchdown |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jul 17 2006 2:36PM |
| User who most recently changed record | STAM |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | NA |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |