Robinson R22 BETA N877HF

Summary

On 14 September 2007 at about 18:15 local time, a Robinson R22 BETA registered N877HF, operated by Universal Air Academy, was involved in an accident near El Monte, California, 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

14 September 2007 at 18:15

Classification

Accident

Location

El Monte, California, United States

Coordinates

Not recorded

Aircraft

Robinson R22 BETA

Registration

N877HF

Category

Helicopter

Engines

1

Operator

Universal Air Academy

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

El Monte → El Monte

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX07LA274

Nobody was injured.

a failure of the main rotor drive system V-belts due to damage sustained when the alternator drive belt failed and pieces of that belt got between the main drive belts and their associated pulleys. A contributing factor was the uneven terrain encountered in the forced landing.

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

Read the full NTSB narrative

While in cruise flight about 1,700 feet agl, the flight instructor heard a loud "bang" from the back of the helicopter. The alternator warning light illuminated, and he initiated the alternator emergency procedure. He noticed the engine's rpm was fluctuating with the main rotor rpm indicating high and the engine rpm low. He entered an autorotation and landed on uneven terrain; the main rotor struck the tail boom, and the helicopter rolled over onto its left side. The helicopter was examined by a Safety Board investigator. The two main drive V-belts were located in the drive compartment with one positioned on the drive pulleys in the middle slot (between the normal operating positions for the forward and aft belts), and the other was located completely off of the drive pulleys. Both belts exhibited damage on the inside including scratch marks, material and color transfers, and gouges consistent with damage by a rubber based foreign object. Rubber and color transfer in a transverse orientation inconsistent with the drive belts was noted on the upper and lower pulleys. The alternator belt was missing and not recovered. The clutch assembly was located in the up position with the actuator fully extended, and the safety stop activated. The oil cooler sustained damage to the outer fins. Rubber transfer was located on the oil cooler, starter, oil lines, and exhaust tube on a plane with the alternator belt's rotation. The alternator belt is located directly below the lower main drive pulley. No other preimpact anomalies with either the airframe or engine were discovered. As a result of this investigation Robinson is changing the specification for the alternator drive belt.

Quoted verbatim from the NTSB record.