What happened
On 11 July 2011, a private flight involving an X’Air R100, registration G-BZER, experienced a sudden engine malfunction while cruising. During level flight, the single BMW R100RS piston engine began to run roughly and experienced a substantial drop in power.
In response to the engine instability, the pilot reduced the throttle and transitioned the aircraft into a glide at approximately 55 mph. Seeking a safe area to land, the pilot identified a long field of barley, noting the presence of power lines at both ends of the field. After confirming the aircraft could clear the nearby lines, the pilot closed the throttle and shut off the master switch at an altitude of roughly 10 ft.
During the landing, the aircraft flared gently but the nose gear struck soft ground, causing it to collapse. The aircraft pitched forward and inverted upon contact with the dense crop. The pilot sustained no injuries during the incident.
The investigation
Following the accident, an examination of the engine was conducted to determine the cause of the power loss. Investigators discovered that the exhaust valve on the left cylinder had detached from its stem. This failure resulted in extensive internal damage to the engine.