What happened
On 28 June 2003, a Rutan Long-EZ, registration EI-CMR, was conducting a private experimental flight near Bunmahon, Co. Waterford. The pilot, accompanied by a passenger, had been performing several descent and climb cycles over the coastline. During one of these maneuvers, the engine began to run roughly.
In an attempt to stabilize the engine, the pilot engaged the carburetor heat and switched fuel tanks, but the performance did not improve. As the engine eventually stopped altogether, the pilot identified a suitable field for an emergency landing. During the landing sequence, the aircraft's nose gear was extended for slow flight. As the pilot approached the field, the aircraft struck an electrical cattle wire, which nicked the propeller and caused minor surface damage to the airframe. Both occupants exited the aircraft without injury.
The investigation
The AAIU examined the aircraft's mechanical condition and the environmental factors present during the flight. An inspection of the fuel system by a SAAC inspector found no contaminants or foreign object damage in the filters or gascolator. However, a subsequent test flight in August 2004 also resulted in an engine failure, prompting a deeper look into the engine components.
Upon overhaul, contractors discovered that the magnetos were in poor condition, featuring worn brushes and outdated distributor gears. Additionally, the carburetor was found to have been running a rich mixture. The investigation also noted that the engine, which had a history of service in a different aircraft, had not undergone a magneto overhaul in seven years, exceeding the manufacturer's recommended intervals.
Findings
- The engine failure was likely caused by a combination of a rich fuel/air ratio and degraded magneto performance.
- Atmospheric conditions, specifically the temperature and dewpoint, were highly conducive to carburetor icing.
- The pilot's use of carburetor heat was intermittent and may not have been sufficient to clear ice buildup during the descent.
- The aircraft's high aerodynamic efficiency allowed it to maintain flight at low power settings, which increased the risk of induction icing in humid conditions.
Safety action
- The owner was advised to install a carburetor temperature gauge in the aircraft.
- A recommendation was made to the IAA to require placards in homebuilt aircraft cockpits, warning passengers of the different airworthiness standards compared to certified aircraft. The IAA subsequently implemented this requirement for all Flight Permits.