Garlick OH-58A+ N48LA

Summary

On 28 July 2010 at about 13:00 local time, a Garlick OH-58A+ registered N48LA, operated by B & S Air Inc, was involved in an accident near Newport, Tennessee, United States. One person was on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

28 July 2010 at 13:00

Classification

Accident

Location

Newport, Tennessee, United States

Nearest airport

None (NONE)

Coordinates

35.9700, -83.1900

Aircraft

Garlick OH-58A+

Registration

N48LA

Category

Helicopter

Engines

1

Operator

B & S Air Inc

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Newport → Jackson

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA10LA379

1 person had minor injuries.

Inadequate maintenance inspections of the main rotor blade inertia screw holes, which resulted in a main rotor blade failure due to fatigue. Contributing to the accident was the pilot's inadequate preflight inspection of the main rotor blades.

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

Read the full NTSB narrative

The pilot completed a preflight inspection and found no problems with the helicopter. He then completed a normal start procedure and increased the rpm to 100 percent flight idle. He was about to increase the collective, when he felt a violent shake, heard a loud noise, and the helicopter began to come apart. A postaccident examination of the wreckage revealed that an outboard 2-foot section of main rotor blade had separated. Metallurgical examination of the separated blade revealed that a fatigue crack originated from an inertia screw hole, located at the bottom surface of the spar portion of the main rotor blade. That crack propagated more than 50 percent of the spar cross section, before fracturing consistent with overstress. A manufacturer alert bulletin instructed operators to visually inspect the inertia screw hole locations on the blade spar with a 10X magnifying glass for cracks and corrosion every 8 hours of flight, or 32 cumulative flights. The outboard section of main rotor blade was secured with eight inertia screws. Although the inertia screw holes were supposed to receive a maintenance inspection every 8 flight hours, they were also a preflight inspection item for the pilot. Review of the helicopter's maintenance logbooks revealed an entry stating that the inertia screw holes had been inspected within the past 8 flight hours; however, corrosion was present in the inertia screw hole that failed. The corrosion and fatigue was most likely present for more than 8 flight hours.

Quoted verbatim from the NTSB record.