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ASN Wikibase Occurrence # 89765
Last updated: 31 May 2020
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Date:31-JAN-2011
Time:11:15
Type:Silhouette image of generic H500 model; specific model in this crash may look slightly different
MD Helicopters MD530F (369FF)
Owner/operator:Pima County Sheriff's Department
Registration: N530RL
C/n / msn: 0602FF
Fatalities:Fatalities: 1 / Occupants: 4
Aircraft damage: Substantial
Category:Accident
Location:Ironwood National Forest, AZ -   United States of America
Phase: Unknown
Nature:Unknown
Departure airport:Tucson, AZ (TUS)
Destination airport:Marana, AZ
Investigating agency: NTSB
Narrative:
The four-place, turbine-powered helicopter was being operated by the county sheriff's department in support of a county emergency communications system development and construction project. The accident flight was intended to enable technical personnel to conduct a site survey for the planned installation of a communications repeater tower near the top of a mountain. The sheriff's department pilot had satisfactorily completed training for and had demonstrated confined area, slope, and pinnacle landings. None of the three passengers were helicopter pilots, and no anti-torque pedals were installed at the front passenger's station. The mountain's remote location and its topography prevented postaccident availability of specific meteorological conditions at the time of the accident, but analysis of available data indicated that mostly overcast skies, intermittent rain, and a generally westerly wind at 10 to 15 knots were present. Those conditions were within the helicopter's and pilot's performance capabilities. The helicopter orbited the peak for general reconnoitering before the pilot attempted a landing. The pilot's selected landing zone was on a relatively level area of a pinnacle on the northeast side of the mountain, and the approach was from the southeast. The passengers reported that during the landing attempt, they felt a bump, and the helicopter rose a few feet, then the nose pitched down, and the helicopter began to spin to the right. The main rotor blades struck a rock outcrop, and the helicopter tumbled and slid about 120 feet down a shallow canyon on the northeast face of the peak before it was halted by rocks and scrub vegetation.

The wreckage was examined in situ, recovered, and examined in detail. All components were accounted for. All damage patterns were consistent with the helicopter's low-speed impact with terrain in the horizontal and vertical planes, and its subsequent tumble down the canyon. The engine successfully met specification power settings during an operational run in a test fixture. No evidence of any preexisting mechanical defect or malfunction was noted during the examination or testing of the airframe and engine. Main and tail rotor damage patterns and debris distribution were consistent with rotor strikes under power. The witness and passenger descriptions of the helicopter's motions are consistent with a tail rotor ground strike and a subsequent loss of directional control. Although no reliable ground scars indicative of a tail rotor strike were found, that was likely precluded by the rocky, hard surface of the landing zone.
Probable Cause: An inadvertent tail rotor strike during an attempted pinnacle landing, which resulted in the pilot's loss of control of the helicopter. Inhospitable terrain/topography contributed to the severity of the accident.

Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20110131X92536&key=1


Revision history:

Date/timeContributorUpdates
31-Jan-2011 21:35 bizjets101 Added
04-May-2015 15:32 TB Updated [Aircraft type, Location, Source, Narrative]
21-Dec-2016 19:25 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
26-Nov-2017 18:47 ASN Update Bot Updated [Operator, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative]

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