ASN Wikibase Occurrence # 145584
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| Date: | Thursday 10 May 2012 |
| Time: | 10:15 |
| Type: |  Robinson R44 Raven II |
| Owner/operator: | iPrerogative, Inc |
| Registration: | N7523S |
| MSN: | 10276 |
| Year of manufacture: | 2004 |
| Total airframe hrs: | 1377 hours |
| Engine model: | Lycoming IO-540 SER |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Near Mount Taylor, north of Grants, New Mexico -
 United States of America
|
| Phase: | En route |
| Nature: | Ferry/positioning |
| Departure airport: | Albuquerque, NM (KABQ) |
| Page, AZ (KPGA) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
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.
Accident investigation:
 |
|
Sources:
NTSB
FAA register: 2. FAA: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?omni=Home-N-Number&nNumberTxt=7523S
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 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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