MD Helicopters MD 900 N912LH

Summary

On 22 March 2006 at about 23:00 local time, a MD Helicopters MD 900 registered N912LH was involved in an accident near Mesa, 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

22 March 2006 at 23:00

Classification

Accident

Location

Mesa, Arizona, United States

Coordinates

33.4608, -111.7283

Aircraft

MD Helicopters MD 900

Registration

N912LH

Category

Helicopter

Engines

2

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Other Work Use

Phase of flight

Not recorded

Route

Mesa → Mesa

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ANC06LA038

Nobody was injured.

The manufacturer's inadequate design clearance of the main rotor blade grip pitch cases, which resulted in damage to the pitch cases when they contacted main rotor perimeter bolts during maneuvering flight.

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

Read the full NTSB narrative

The experimental category flight was being operated by the helicopter manufacturer under Title 14, CFR Part 91, when the accident occurred. The commercial certificated helicopter pilot was conducting a series of climbing and descending turns while a second helicopter, flying alongside, filmed the maneuvers. According to a safety representative for the helicopter manufacturer, all of the maneuvers were conducted within the normal limitations of the helicopter. The maneuvers were completed uneventfully, with no in-flight anomalies noted, and the helicopter returned to the manufacturer's base. While conducting a routine daily inspection of the helicopter in preparation for the next scheduled flight, maintenance technicians discovered damage to the main rotor hub's five pitch case assemblies, slightly aft of the upper damper cap. The damage was a result of the pitch cases striking the upper main rotor hub perimeter bolts. All five pitch cases were damaged beyond repairable limits, and were replaced. The safety representative for the helicopter manufacturer reported that the anticipated corrective action will be to increase the clearance between the pitch cases and the main rotor hub perimeter bolts by trimming additional material from the inboard and upper portion of the main rotor pitch case assemblies during the manufacturing process.

Quoted verbatim from the NTSB record.