# NTSB CEN12LA289: Robinson Helicopter R44 II, N7523S, Grants, NM, May 10, 2012 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: May 10, 2012, 10:15 local (16:15 UTC) - Place: Grants, NM - Coordinates: 35.150863, -107.829208 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.1509&lon=-107.8292&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report April 10, 2013 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA FSDO - NTSB case key (mKey): 83606 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN12LA289 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/83606/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=83606 - Page: https://openairdocs.org/ntsb/CEN12LA289 ## 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. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine fuel and control: fuel control/carburetor](https://openairdocs.org/ntsb-findings/01057322): Aircraft › Aircraft power plant · Related operating info (probable cause); cases with it: [All aircraft, 195 cases](https://openairdocs.org/ntsb-findings/01057322/cases.md) - [Action: unnecessary action](https://openairdocs.org/ntsb-findings/02041045): Personnel issues › Action/decision · Instructor/check pilot (probable cause); cases with it: [All aircraft, 52 cases](https://openairdocs.org/ntsb-findings/02041045/cases.md) - [Terrain: mountainous/hilly terrain](https://openairdocs.org/ntsb-findings/03021010): Environmental issues › Physical environment · Ability to respond/compensate (probable cause); cases with it: [All aircraft, 329 cases](https://openairdocs.org/ntsb-findings/03021010/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Autorotation: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis 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. ## Factual narrative On May 10, 2012, about 1015 mountain daylight time, a Robinson R44 II helicopter, N7523S, performed an autorotation following a loss of engine power near Grants, New Mexico. The certificated flight instructor (CFI) and commercial pilot were not injured and the helicopter was substantially damaged. The helicopter was owned and operated by iPrerogative Inc, Washington, Utah, under the provisions of 14 Code of Federal Regulations Part 91 as a positioning flight. Visual meteorological conditions prevailed for the flight which operated on a visual flight rules flight plan. The helicopter departed the Albuquerque International Airport (KABQ), Albuquerque, New Mexico, about 0900, and was destined for the Page Municipal Airport (KPGA), Page, Arizona. According to a statement provided by the CFI, while cruising over mountainous terrain, at 10,000 feet mean sea level (msl), the CFI slowed the helicopter to 70 knots and initiated a practice autorotation, in order to maintain autorotation proficiency. The pilot reported checking 80 percent engine rpm at least twice during the practice autorotation. About 9,200 feet msl (about 600 feet above ground level), the CFI attempted to restore engine power but the engine had quit producing power which was verified by the engine tachometer. The pilot continued the autorotation and lined up with the best available landing area and landed. On touchdown, the helicopter’s main rotor blade contacted the tail boom severing the tail boom. Substantial damage was sustained to the main rotor blades, tail boom, and tail rotor blades. A postaccident engine run was conducted by the National Transportation Safety Board and a technical representative from Lycoming Engines. The engine started and ran for several minutes; however, the engine occasionally ran rough at idle power with a full rich mixture setting. Leaning the fuel mixture via the cockpit mixture control improved engine performance. The density altitude at the time of the engine run was approximately 8,100 feet. A review of maintenance records showed that maintenance work was performed in Florida at an altitude of 100 feet mean sea level. Any adjustment to the fuel control unit, which sets the idle mixture, would have been set at this altitude by maintenance personnel. ## Aircraft - Registration: N7523S (not matched to a registry record) - Reported make and model: ROBINSON HELICOPTER COMPANY R44 II - Category: Helicopter - Serial number: 10276 - Airframe hours: 1377.3 - Engines: LYCOMING IO-540 SER 300 horsepower reciprocating - Damage: Substantial damage - Flight: Ferry, Part 91 - Operator: iPrerogative, Inc - Registered owner: Rotortrends Inc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 29, 2012 - Departed: KABQ, Albuquerque, NM - Destination: KPGA, Page, AZ - Flight plan: VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 32; injuries: none; commercial, flight instructor; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, without waivers/limitations; last flight review May 3, 2011; seat: right; flight hours: 613 total, 138 in this make and model, 529 as pilot in command, 32 in the last 90 days, 24 in the last 30 days, 8 in the last 24 hours - Pilot; age 30; injuries: none; commercial; medical: class 2, without waivers/limitations; seat: left ## Weather - Conditions: Visual (VMC), Day - Wind: 170° at 5 knots - Lowest ceiling: none - Temperature: 63 °F, dew point 25 °F - Altimeter: 30.05 inHg - Observed at: KGNT ## Docket (2 files) The files NTSB released with the investigation on February 27, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=83606. 1.8 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40382836&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Statement of Party Representatives to NTSB Investigation (item 2, .PDF, 496 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40384408&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.