What happened
On 21 April 2003, a Europa Classic Monowheel, registration EI-COE, was performing a test flight at Coonagh Aerodrome, Co. Limerick, to establish parameters for a Permit to Fly. Following a standard touchdown on runway 28, the aircraft began to deviate laterally during the landing roll.
As the aircraft slowed, the pilot attempted to correct the leftward veer using the rudder, but the oscillations became increasingly unstable. In an attempt to regain control, the pilot applied the brakes, which instead caused the aircraft to swing sharply to the right by approximately 70 degrees. The aircraft eventually came to a halt roughly 3 metres from the edge of the runway. The maneuver caused the propeller and the port wingtip to strike the tarmac, resulting in damage to the engine cowling, propeller, spinner, and wingtip. There were no injuries to the pilot.
The investigation
The investigation examined the handling characteristics of the monowheel configuration and the circumstances of the landing. The pilot noted that the aircraft's ground handling on hard surfaces was extremely demanding, as the tailwheel provides minimal stabilizing influence during the initial deceleration phase. Furthermore, the application of brakes appeared to exacerbate the instability by increasing the unstable force couple and causing the tail to rise.
The investigation also looked into the aircraft's instrumentation, noting the pilot's suspicion of a potential leak in the pitot-static system, which may have resulted in a higher approach and landing speed than indicated. Additionally, the role of the inspecting engineer in verifying the integrity of the pitot-static system prior to the aircraft being declared fit for flight was reviewed.
Findings
- The pilot lost directional control during the landing roll, leading to the aircraft departing the runway.
- The monowheel undercarriage configuration is inherently difficult to manage on tarmac surfaces due to the lack of stabilizing influence from the tailwheel during deceleration.
- Applying brakes during the unstable oscillation increased the instability of the aircraft.
- The pilot could have potentially prevented the excursion by applying full power for a go-around at the first sign of directional instability.
Safety action
- The owner is advised to install an approved modification to replace the monowheel undercarriage with a tricycle undercarriage to improve ground handling on hard surfaces.
- It is recommended that inspectors perform and record a leak check on the pitot-static system before releasing an aircraft as fit to fly.