Engine failure during motor glider flight leads to emergency landing in Heeze

Casualties unknown • Emergency landing after engine problem, Diamond HK 36 TC, Heeze, NL

A Diamond HK 36 TC motor glider experienced engine restart failures during a local flight, resulting in a forced landing in a potato field near Heeze.

What happened

On June 17, 2006, a Diamond HK 36 TC motor glider, registration PH-1157, departed from Eindhoven airport for a local flight. The aircraft, carrying a pilot and one passenger, initially climbed to approximately 2,500 feet. After finding thermals near Leende, the pilot shut down the engine to glide. While attempting to utilize a cumulus cloud near Heeze, the pilot decided to restart the engine at an altitude of roughly 1,640 feet.

The pilot made several attempts to restart the engine using different settings, including variations in throttle and choke usage. Despite following the checklist, the engine failed to ignite. As the aircraft's descent rate increased to over 2 meters per second and the altitude dropped to 650 feet, the pilot ceased restart attempts to focus on an emergency landing. After evaluating several landing sites to avoid obstacles like power lines and trees, the pilot opted to land in a nearby potato field to avoid flying low over a barbed-wire fence. During the touchdown, the nose gear collapsed, causing minor damage to the aircraft, though there were no injuries to the occupants.

The investigation

The investigation relied on the pilot's report, as investigators did not visit the site. Technical inspections of the airframe and engine were conducted by Gomolzig Flugzeug- und Maschinenbau GmbH, while the propeller and accumulator were examined by MT-Propeller Gerd Mühlbauer GmbH. The technical examination found no mechanical defects that would explain the engine's failure to start.

Findings

  • The exact cause of the engine's failure to restart could not be definitively determined.
  • The pilot's decision to prioritize passenger comfort over technical maneuvers contributed to the situation; specifically, the pilot did not attempt a low-nose attitude to allow the propeller to windmill during the second start attempt because he did not want to unsettle the passenger.
  • The pilot's focus on restart attempts at low altitude delayed the necessary planning for an emergency landing site.
  • The pilot underestimated the increased descent rate caused by the propeller not being in the feathered position.

Safety action

  • Pilots should not omit essential emergency maneuvers, such as adopting a low-nose attitude for engine windmilling, simply due to the presence of a passenger.

Probable cause

The engine failure to restart could not be mechanically identified, but the incident was exacerbated by the pilot's decision to prioritize passenger comfort over necessary engine-restart maneuvers and a delay in landing site selection due to continued restart attempts at low altitude.

Frequently asked questions

What happened in the null aircraft accident near Emergency landing after engine problem, Diamond HK 36 TC, Heeze, NL?

A Diamond HK 36 TC motor glider experienced engine restart failures during a local flight, resulting in a forced landing in a potato field near Heeze.

What aircraft was involved and where did it happen?

The accident on null involved a aircraft, at Emergency landing after engine problem, Diamond HK 36 TC, Heeze, NL.

What was the probable cause of the accident?

The engine failure to restart could not be mechanically identified, but the incident was exacerbated by the pilot's decision to prioritize passenger comfort over necessary engine-restart maneuvers and a delay in landing site selection due to continued restart attempts at low altitude.

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