McDonnell Douglas 369E N40NT

Summary

On 25 June 2002 at about 21:10 local time, a McDonnell Douglas 369E registered N40NT was involved in an accident near Ontario, California, United States. 2 people were on board and 2 were seriously injured. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

25 June 2002 at 21:10

Classification

Accident

Location

Ontario, California, United States

Nearest airport

Ontario (ONT)

Coordinates

34.0467, -117.6017

Aircraft

McDonnell Douglas 369E

Registration

N40NT

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Public Use

Phase of flight

Not recorded

Route

Ontario → Ontario

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

LAX02GA209

2 people were seriously injured.

The mechanic's improper maintenance procedures (FOD prevention) during a 100-hour inspection, which resulted in foreign object damage (FOD) to the compressor section and catastrophic engine failure. Factors were the presence of vehicles and power lines partially obstructing the forced landing site that necessitated the pilot's use of rotor system energy to avoid, which resulted in a hard landing.

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

Read the full NTSB narrative

The helicopter landed hard during an autorotation following a catastrophic engine failure in the takeoff initial climb. The engine lost all power during the initial climb out on a test flight following the completion of a 100-hour inspection. The pilot initiated an autorotative descent. While he maneuvered to avoid automobile traffic and power lines, the main rotor rpm decayed. The helicopter touched down hard on a street and was destroyed by an intense fuel-fed ground fire. The accident occurred during the first flight following maintenance performed by the on-board passenger, a mechanic employed by the operator. The helicopter's airframe was examined and no evidence of preimpact anomalies were found. Upon splitting the engine's case halves, all of the compressor blades on stages 1 through 6 were found either damaged or missing. A piece of a wire tie wrap was noted adhering to one of the case halves in the 6th stage area. Additionally, metallic debris was found in the outer combustion case (OCC). The metallurgical examination of the OCC debris revealed it was composed of an aluminum-magnesium-silicon alloy, which was foreign to components used in the engine. Wire tie wraps, similar to the tie wrap found in the engine, were also found in the accident site debris field. Similar wire tie wraps were additionally observed in storage at the operator's maintenance facility. The air intake to the engine's compressor is enclosed in a plenum chamber on the top of the helicopter. Prior to the accident, the mechanic had been observed performing maintenance in this area.

Quoted verbatim from the NTSB record.