A loose spark plug caused a microlight to crash into a field near Bishopstone.

The crash happened in the morning of February 21 after the MW7 aircraft took off from an airfield near Winchester, Hampshire. An air accident investigation report into the crash says the 40-year-old pilot of the microlight, owned by Duncan Alexander Couchman of Bradley Road, Swindon, had flown one uneventful flight and landed to re-fuel. He then took off again, but at around 1,000 feet the engine lost power.

The pilot, who had 140 hours flying experience, then made an emergency landing in a field. As the aircraft touched down, the wheels were ripped off and it over-turned leaving the pilot upside down in his safety harness. The pilot received only minor injuries but the aircraft was badly damaged.

The report continued: “On subsequent inspection, it was evident that the loss of power had been caused by one of the spark plugs becoming unscrewed from the front cylinder of the engine.

“The spark plugs and the front cylinder head temperature (CHT) probe were last replaced prior to the aircraft’s Permit to Fly renewal, more than six months and six hours 30 minutes flight time before the accident.

“The spark plug that became unscrewed, causing the loss of power, was the one that had the new CHT probe fitted beneath it.

“The ring from the CHT probe was missing after the accident, but the pilot thought it unlikely that the ring could have detached from the cylinder head, leaving the spark plug loosely screwed in.

“He considered it more probable that the threads of the spark plug may have bound on the CHT probe when the two were replaced, giving a misleading torque reading.

“Therefore, it is possible that the spark plug was not correctly tightened up when it was installed.”