Boise-Gowen Field Airport: Boise, Idaho

Airport is located 3 miles south of Boise, Idaho.

Accident occurred Tuesday, July 24, 2007 in Boise, ID
Probable Cause Approval Date: 11/29/2007
Aircraft: Robinson R22 Beta II, registration: N147SH
Injuries: 2 Minor.
The flight instructor reported that during their fifth practice autorotation, the student let the rotor rpm decay to the point that the certified flight instructor (CFI) attempted to intercede and perform a run on landing. The student and CFI both struggled with each other on the controls until the helicopter hit the ground hard. During the impact sequence, the helicopter spun around, and ultimately came to rest on the left side.
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Accident occurred Saturday, March 31, 2007 in Boise, ID
Probable Cause Approval Date: 6/27/2007
Aircraft: Cessna T206H, registration: N65067
Injuries: 2 Uninjured.
While attempting to land in variable wind conditions, with gusts to about 15 knots, the pilot inadvertently allowed the aircraft to porpoise. During that sequence, the nose gear hit the runway hard a number of times, and ultimately sustained damage that made the aircraft hard to control. The pilot then lost control of the aircraft, which departed the side of the runway.
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On January 7, 2007, approximately 1145 mountain standard time, a Bell 206B helicopter, N1882, impacted the terrain while in a low hover about 10 miles northeast of Boise, Idaho. The airline transport pilot, who was the sole occupant, was not injured, but the aircraft, which is operated by Idaho Helicopters, sustained substantial damage. The 14 CFR Part 91 local deer herding flight, was being conducted in visual meteorological conditions. No flight plan had been filed.

According to the pilot, after completing two local deer herding flights, he landed the helicopter and waited about five minutes for the ground crew to be ready for him to start another herding flight. At the beginning of the third flight, he lifted off into a hover, and then performed a pedal-turn into the wind prior to entering translational lift. During the turn, the snow pad on one of the helicopter’s skids caught in some tall brush, resulting in a dynamic rollover into the terrain. According to the pilot, there was no problem with the helicopter’s flight controls, but he simply failed to see that there was tall brush ( approximately six feet high) behind and to the right of the aircraft.
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On October 5, 2006, at approximately 1100 mountain daylight time, a Cessna 182M, N70946, was substantially damaged when it impacted a temporary construction fence during taxi at Boise Air Terminal, Boise, Idaho. The private pilot, the sole occupant of the airplane, was not injured. The pilot/owner was operating the aircraft under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the cross-country flight which originated from Nampa, Idaho, approximately 20 minutes before the accident. No flight plan had been filed.

The pilot said that he was taxiing to his hangar with the airplane's nose wheel on the centerline of the taxiway. The airplane's left wing struck a temporary construction fence that had been moved onto the edge of the taxiway. The left wing leading edge was damaged approximately 6 feet in from the wingtip and the left aileron was separated from the wing.
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Accident occurred Friday, August 11, 2006 in Boise, ID
Probable Cause Approval Date: 11/29/2006
Aircraft: Robinson R-22B, registration: N228SH
Injuries: 2 Uninjured.
While demonstrating a 180 degree autorotation to landing, the instructor pilot inadvertently allowed the helicopter to attain an excessive rate of descent. Although he added power and initiated a go-around, he had waited too long to begin the go-around, and he was unable to keep the helicopter from impacting the end of the runway and bouncing back into the air. After hover-taxiing to parking, the instructor inspected the helicopter, whereupon it was determined it had sustained substantial damage.
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On May 15, 2006, approximately 1535 mountain daylight time, a Schweizer 269C helicopter, N2096W, sustained substantial damage following a hard landing while performing an autorotation near Boise, Idaho. The certified helicopter instructor pilot and his student were not injured. The helicopter was registered to and operated by Aviation Specialties Limited of Boise. Visual meteorological conditions prevailed for the local instructional flight, which was operated in accordance with 14 CFR Part 91, and a flight plan was not filed. The helicopter departed from the Boise Air Terminal/Gowen Field (BOI), about 1415.

According to the Pilot/Operator Aircraft Accident/Incident Report (NTSB Form 6120.1) submitted to the NTSB investigator-in-charge (IIC), the instructor pilot reported that approximately 1.3 hours into the flight, at an altitude of 3,900 feet mean sea level (msl) or 1,000 feet above ground level (agl), the instructor pilot, who was occupying the left seat and in control of the helicopter, instructed the student, who occupied the right seat, to reduce the throttle to idle to simulate an engine failure at altitude. The instructor pilot stated that after the throttle was reduced to idle he entered an autorotation, maneuvered the helicopter into the wind, and then noticed the engine had failed. The instructor pilot reported that he decided not to attempt to do an engine restart in flight, and the autorotation was completed to the ground into the wind to a grass field with a slight up slope. The instructor pilot further reported that after the helicopter's
skids impacted terrain, it slid backwards approximately 15 feet before the tail boom flexed up and was impacted by the main rotor. The hard landing resulted in substantial damage to the tail boom, all three main rotor blades, and the tail rotor drive shaft. There was no post accident fire. The aircraft was subsequently recovered to a secured area at the facilities of Aviation Specialties Limited, where a further examination by representatives of the Federal Aviation Administration (FAA) would be conducted.

On May 18, 2006, two FAA aviation safety inspectors from the Boise Flight Standards District Office, Boise, Idaho, participated in an engine run. The inspection revealed no anomalies which would have precluded normal operation of the engine. The inspectors reported that while the idle rpm and idle mixture were set for winter temperatures, and that while being adjusted poorly for the altitude and temperature on the day of the flight, the failure of the instructor pilot to follow the cautions in the helicopter's flight manual resulted in the loss of power. (Refer to attached inspector's statement)

According to the Schweizer Aircraft Corporation's Model 269C Helicopter Pilot's Flight Manual, page 4-23, #4-16, ENGINE IDLE AT ALTITUDE, revised 15 June 1994, this section states:

Engine idle speeds at high density altitude may be less than those set at sea level conditions.

WARNING: AVOID THROTTLE CHOPS TO FULL IDLE AT ALTITUDES ABOVE 7000 FEET, TO AVOID POSSIBILITY OF ENGINE STOPPAGE. (Refer to attached Schweizer Aircraft Corporation Pilot's Flight Manual, Normal Procedures, page 4-23)

At 1524, the weather reporting facility at BOI, reported wind 140 degrees at 13 knots, visibility 10 statute miles, sky clear, temperature 33 degrees C, and a density altitude of 5,500 feet.
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On August 27, 2005, about 1445 mountain daylight time, a Robinson R22 Beta helicopter, N3825, sustained substantial damage subsequent to a hard landing following a practice autorotation at the Boise Air Terminal, Boise, Idaho. The helicopter is owned by Silver State Helicopters of North Las Vegas, and was being operated as a visual flight rules (VFR) instructional flight under Title 14 CFR Part 91, when the accident occurred. The certified flight instructor, and student pilot receiving helicopter training, were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local instructional flight. The flight originated from Boise, Idaho, approximately one hour prior to the accident.

In a written statement dated August 27, 2005, and subsequent telephone conversation with the NTSB IIC, the instructor pilot reported he and the student pilot were practicing power recovery auto rotations at the Boise airport. During the tenth practice autorotation, with the student pilot on the controls, the instructor noted a lower than normal main rotor RPM (approximately 94 percent) and elected to take the controls in an effort to make the necessary inputs to recover from the maneuver. The instructor pilot reported that during the transition (approximately 60 feet agl), there was a "struggle" for the controls and corrective action was delayed resulting in a hard landing and substantial damage to the helicopter.

The instructor pilot stated that he does not recall verbalizing the transfer of control to the student pilot.