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ASN Wikibase Occurrence # 145584
Last updated: 20 June 2018
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Type:Silhouette image of generic R44 model; specific model in this crash may look slightly different
Robinson R44 Raven II
Owner/operator:iPrerogative, Inc
Registration: N7523S
C/n / msn: 10276
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Location:Near Mount Taylor, north of Grants, New Mexico -   United States of America
Phase: En route
Departure airport:Albuquerque, NM (KABQ)
Destination airport:Page, AZ (KPGA)
Investigating agency: NTSB
The helicopter, which had been based at sea level, had recently been sold, and the flight instructor and a commercial pilot were flying it across the country to its new base. While in cruise flight over mountainous terrain at high density altitude, the flight instructor initiated a practice autorotation for the purpose of maintaining proficiency. During the autorotation, the engine stopped producing power. The instructor continued the autorotation to a landing; however, during the landing, the main rotor blades severed the tail boom. A postaccident engine run at high density altitude revealed that the engine ran rough at an idle power setting with a full rich fuel mixture. Leaning the fuel mixture improved engine performance. It is likely that the fuel control unit was set by maintenance personnel to provide a rich mixture at sea level, which resulted in poor engine performance at high density altitudes.
Probable Cause: The loss of engine power due to an excessively rich fuel mixture that occurred during operations at idle power settings at a high density altitude. Contributing to the accident was the flight instructor’s poor decision-making in choosing to practice an unnecessary autorotation over mountainous terrain.


FAA register: 2. FAA:

Revision history:

11-May-2012 11:22 gerard57 Added
11-May-2012 13:10 Geno Updated [Time, Aircraft type, Registration, Cn, Operator, Location, Departure airport, Source, Narrative]
12-May-2012 01:54 RobertMB Updated [Aircraft type, Operator, Location, Narrative]
16-May-2012 21:05 Geno Updated [Time, Nature, Source, Damage, Narrative]
26-Feb-2016 20:56 Dr.John Smith Updated [Time, Operator, Location, Departure airport, Destination airport, Source, Narrative]
21-Dec-2016 19:28 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
27-Nov-2017 20:40 ASN Update Bot Updated [Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative]

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