ASN Wikibase Occurrence # 157539
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| Date: | Monday 8 July 2013 |
| Time: | 08:20 |
| Type: |  Robinson R-22 Beta |
| Owner/operator: | Upper Limit Aviation Inc |
| Registration: | N712U |
| MSN: | 3676 |
| Year of manufacture: | 2004 |
| Engine model: | Lycoming O-360-J2A |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Destroyed |
| Location: | Tibble Fork Reservoir, American Fork Canyon, near Alta, Utah -
 United States of America
|
| Phase: | En route |
| Nature: | Training |
| Departure airport: | Heber City Municipal Airport (Russ McDonald Field), Heber City, Utah ( |
| Salt Lake City International Airport, Salt Lake City, Utah (SLC/KSLC) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
On July 8, 2013, about 08:20 MDT (Mountain Daylight Time), a Robinson R22 Beta II, N712U, collided with mountainous terrain in a wilderness area near Alta, Utah. The helicopter was registered to Tumbleweed Leasing Co, Inc., and operated by Upper Limit Aviation, Inc., under the provisions of 14 Code of Federal Regulations Part 91. The flight instructor (CFI) and private pilot undergoing instruction sustained minor injuries. The helicopter was destroyed during the accident sequence. The local instructional flight departed Heber City Municipal Airport (Russ McDonald Field), Heber, Utah, about 08:00 MDT, with a planned destination of Salt Lake City International Airport, Salt Lake City, Utah. Visual meteorological conditions prevailed, and a company flight plan had been filed.
The CFI stated that on the outbound journey that morning, they departed from Salt Lake City about 06:30 MDT, taking a route of flight that followed roads through mountain passes to the north of the accident site. The passes were lower than the accident elevation. The pilot undergoing instruction reported that for the return flight, the CFI decided to take a more direct route, overflying the mountain peaks east of Salt Lake City.
The pilot undergoing instruction was controlling the helicopter for both the departure from Heber City, and the climb to the west towards the Lone Peak Wilderness area. The CFI reported that throughout the ascent, the helicopter was able to maintain a climb rate of about 500 feet per minute. The outside air temperature gauge indicated 12 degrees C, the manifold pressure indicated 20 inches of mercury, and carburetor heat was on in order to keep the carburetor temperature gauge within the yellow band. He stated that the helicopter was maintaining an airspeed of 65 knots as they passed along a ridge at an elevation of about 10,000 feet msl, and by that time the manifold pressure had reduced to 18 inches. They began the descent down the back side of the ridge, during which time the pilot began to raise the collective in order to lower the descent rate. As soon as he did, the rotor speed began to decay, and the low rotor rpm warning sounded. The CFI took control of the helicopter, and lowered the collective, while simultaneously increasing engine power with the throttle control. Rotor speed increased, and a short time later the CFI raised the collective in order to arrest the descent; however, the low rotor rpm warning sounded again. The CFI again lowered the collective and applied power, and the rotor speed again began to decay. This cycle continued two more times, and as the helicopter approached the ground, the CFI applied aft cyclic control in an effort to reduce forward speed. A few seconds later, the main skids struck rocks, and the helicopter tumbled.
The helicopter came to rest at an elevation of about 9,700 feet, 1.3 miles west of the 11,321-foot-tall summit of Mount Baldy. The ridge line adjacent to the accident site traversed from north to south, and was at an elevation of about 11,000 feet along the presumed flight path. The terrain at the accident site fell away over the next 5 miles to the southwest, towards the city of Alpine, 5,000 feet below. The CFI stated that they maintained a ground clearance of between 300 and 400 feet both during the climb, and ridge traversal.
Probable Cause: The flight instructor's decision to follow a route over mountainous terrain in conditions that exceeded the helicopter’s ability to maintain terrain clearance.
Accident investigation:
 |
|
Sources:
NTSB
2. FAA register: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?omni=Home-N-Number&nNumberTxt=712U
3. http://helihub.com/2013/07/08/08-jul-13-n712u-robinson-r22b-american-fork-canyon-us-utah/
4. https://www.theepochtimes.com/utah-helicopter-crash-update-no-deaths-two-survivors_161556.html
5. http://airflightdisaster.com/index.php/two-survive-robinson-crash-in-utah/
History of this aircraft
Other occurrences involving this aircraft
| 18 June 2007 | N712U | Upper Limit Aviation | 0 | Park City, Utah | |
sub |
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 09-Jul-2013 15:21 | gerard57 | Added |
| 14-Oct-2016 18:34 | Dr.John Smith | Updated [Time, Operator, Location, Nature, Departure airport, Destination airport, Source, Narrative] |
| 21-Dec-2016 19:28 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 29-Nov-2017 08:48 | ASN Update Bot | Updated [Other fatalities, Departure airport, Destination airport, Source, Narrative] |
| 22-Aug-2018 23:47 | Dr.John Smith | Updated [Time, Other fatalities, Departure airport, Destination airport, Source, Narrative] |
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