What aircraft was involved and where did it happen?

The accident on null involved a aircraft, registration EI-BKT, at IE.

What was the probable cause of the accident?

The engine experienced a flame-out due to the ingestion of an exhaust plume characterized by low oxygen, high heat, and high water vapor, which quenched the combustion process.

Engine Flame-out Caused by Power Station Exhaust Plume

An Agusta B206 Jetranger experienced a sudden engine failure after flying into an invisible exhaust plume near Dublin Port.

What happened

On September 11, 2002, an Agusta B206 Jetranger, registration EI-BKT, was conducting aerial photography for a television documentary near Dublin Port. While flying near two large power station chimneys, the helicopter entered the exhaust plume of an active chimney. This caused the engine to suffer an immediate flame-out and lose all power.

The pilot initiated an autorotation and managed to land the aircraft on a nearby beach. To avoid a forward pitch-over on the soft, wet ground, the pilot raised the collective during the touchdown. Although the crew escaped without injury, the aircraft sustained heavy landing damage, specifically involving the main gearbox.

The investigation

The AAIU investigation examined the flight path, engine performance, and environmental conditions. Investigators reviewed camera footage, which revealed that the plume was nearly invisible until the aircraft was extremely close to the chimney. The investigation also analyzed the atmospheric composition of the plume, noting that the power station was using natural gas, which produces exhaust with high moisture and heat but low visibility.

Technical inspections at Dublin Airport confirmed that the sudden movement of the gearbox during landing caused a spike to strike a striker plate, indicating significant mechanical stress. The investigation also noted that the engine lacked an auto-ignition system, which might have assisted in maintaining combustion.

Findings

The engine flame-out was caused by the ingestion of an exhaust plume containing high temperatures, high moisture content, and depleted oxygen levels.

The plume was difficult to detect visually because it was located near the horizon and was largely transparent due to the use of natural gas.

The heavy landing damage was a result of the pilot raising the collective to prevent a pitch-over, which caused the rotor RPM to drop and the blades to flap, rocking the gearbox.

Safety action

Following the investigation, the Irish Aviation Authority (IAA) issued an Aeronautical Information Circular (AIC) to alert pilots to the dangers of engine flame-outs when operating near environments with contaminated atmospheres, such as power station plumes, forest fires, or volcanic activity. The AAIU also recommended that the IAA review the use of the chimneys as a VFR reporting point to minimize the risk of future incidents.