Robinson R22 BETA N956SH

Summary

On 20 September 2009 at about 20:09 local time, a Robinson R22 BETA registered N956SH, operated by Hillsboro Aviation Inc, was involved in an accident near Forest Grove, Oregon, United States. 2 people were on board and 2 died. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

20 September 2009 at 20:09

Classification

Accident

Location

Forest Grove, Oregon, United States

Nearest airport

Hillsboro (HIO)

Coordinates

45.8100, -123.1783

Aircraft

Robinson R22 BETA

Registration

N956SH

Category

Helicopter

Engines

1

Operator

Hillsboro Aviation Inc

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

Hillsboro → Hillsboro

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR09FA459

2 people died.

The flight crew’s failure to maintain adequate main rotor speed while maneuvering, which resulted in a main rotor blade stall and an uncontrolled descent into terrain.

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

Read the full NTSB narrative

The pilot under instruction was preparing for a certified flight instructor (CFI) check ride and was in the left seat. The CFI was in the right seat, and the two airmen were going to practice autorotations with power recoveries. A witness with helicopter experience observed several uneventful autorotations and then stopped watching; another witness heard a bang. The witnesses then observed the helicopter descending upright with the left skid low. Investigators examined the wreckage and observed signatures indicating that the engine and main rotor blades were rotating at a low speed at impact. The main rotor blades were also coned upward, which is indicative of a low main rotor rpm state. A safety notice issued by the helicopter's manufacturer notes that main rotor blade stall due to low main rotor rpm causes a high percentage of helicopter accidents. It points out that the stall causes the main rotor rpm to rapidly decrease, and leads to an immediate uncontrolled descent.

Quoted verbatim from the NTSB record.