Robinson R44 II N7523S

Summary

On 10 May 2012 at about 16:15 local time, a Robinson R44 II registered N7523S, operated by iPrerogative, Inc, was involved in an accident near Grants, New Mexico, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

10 May 2012 at 16:15

Classification

Accident

Location

Grants, New Mexico, United States

Coordinates

35.1509, -107.8292

Aircraft

Robinson R44 II

Registration

N7523S

Category

Helicopter

Engines

1

Operator

iPrerogative, Inc

Operating rule

Part 91: General Aviation

Purpose of flight

Ferry

Phase of flight

Not recorded

Route

Albuquerque → Page

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN12LA289

Nobody was injured.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.