Robinson R22 BETA N225G

Summary

On 24 March 2005 at about 19:07 local time, a Robinson R22 BETA registered N225G, operated by Guidance Helicopter, Inc., was involved in an accident near Prescott, Arizona, 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

24 March 2005 at 19:07

Classification

Accident

Location

Prescott, Arizona, United States

Nearest airport

Ernest A. Love Field (PRC)

Coordinates

34.6767, -112.4100

Aircraft

Robinson R22 BETA

Registration

N225G

Category

Helicopter

Engines

1

Operator

Guidance Helicopter, Inc.

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

Prescott → Prescott

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX05LA122

Nobody was injured.

The company mechanic's improper maintenance actions, which resulted in the total failure of the main rotor drive belt system on approach to landing. A factor was the soft terrain.

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

Read the full NTSB narrative

The helicopter's main rotor drive belts broke on the base leg and the helicopter rolled over during the subsequent autorotation and landing. The instructor said that he monitored his student during the preflight inspection of the helicopter. No evidence of any problem was detected. The instructor reported that there were no outstanding airworthiness issues with the helicopter. The accident occurred while he was preparing his student for the private pilot certification check ride. The lesson plan/maneuver that he intended the student to practice was a run-on landing. On base leg to runway 21R, while cruising about 60 knots at 300 feet above ground level, the helicopter's nose suddenly yawed left and then right. Concurrently the helicopter shook, and the clutch light illuminated. The instructor took the controls from his student and entered an autorotative descent. About 20 feet above ground level he commenced a cyclic flare for the landing. The underlying terrain was soft sand, and the helicopter rolled over during touchdown. Upon exiting the helicopter, the instructor observed that the V-belts were shredded. A company mechanic had performed a 100-hour inspection about 4.3 hours prior to the accident flight. During the inspection, he had loosened the self-locking nut on the belt actuator housing assembly and had rotated the down-limit stop screw upward until the screw bottomed out in the actuator housing in the full up position. The mechanic forgot to reposition the stop screw and tighten the nut. This action resulted in the main rotor drive V-belts becoming excessively loose. The belts exited their seated position on the lower pulley sheave and were severed.

Quoted verbatim from the NTSB record.