History of the Flight
On 13 July 2008, at approximately 1135 UTC, a Europa G-MIME departed Caernarfon Airfield, Gwynedd, for a private flight. During start-up, the pilot noted that the landing gear outrigger down-and-locked indicator lights were not operating. As both lights were affected, he suspected a continuity problem in the common earth return lead. Since the modification was owner-installed and not required for flight, he chose to proceed.
While flying a circuit to land on Runway 26, the pilot observed a pair of slower microlight aircraft ahead and ensured his speed was not excessive. On the base leg at an airspeed of 60 to 65 kt, he lowered the flaps and landing gear in a slow and progressive manner to avoid sudden trim changes. There was a slight crosswind from the left, and after touchdown he applied left aileron to compensate. As the aircraft slowed on the runway, it began to roll to the right, and it became evident that the right landing gear outrigger had not locked down. Despite applying full left aileron and right rudder, the pilot could not prevent the aircraft from veering left and departing the runway. The aircraft pitched nose down, causing the propeller blade tips to strike the runway surface. On subsequent examination, the right outrigger was found locked down; no reason for its initial failure to lock could be identified.
Aircraft Information
G-MIME was equipped with the monowheel landing gear configuration, comprising a single large retractable mainwheel, a fixed tailwheel, and a pair of small wheels on retractable outrigger legs mounted on the wings outboard of the flaps. The landing gear and flap systems were interconnected and mechanically operated via a single cockpit lever. The rate of lever movement directly controlled the rate of downward movement of the landing gear and flaps. The outriggers locked down via latch mechanisms. The pilot had modified the aircraft to include green indicator lights that illuminated when the outriggers were locked down, as their position could not be seen from the cockpit. He had also incorporated additional modifications, in conjunction with the PFA (now LAA) and the manufacturer, to address known mechanical problems in the landing gear outrigger system.
Discussion
The pilot reported being aware of previous cases of Europa outriggers failing to lock down. Possible causes considered included mechanical reasons due to design limitations or lowering the flaps and landing gear at too high an airspeed. Owners had reported that when the flaps and landing gear were lowered at speeds of 75 to 80 kt, the outriggers did not always lock down immediately but would do so as airspeed reduced. According to the pilot, modifications to G-MIME had eliminated mechanical shortcomings, and the airspeed was not excessive when he lowered the system. He had lowered the flaps and landing gear slowly and progressively to avoid trim effects. After discussion with another Europa owner, he concluded that a more positive lowering might achieve more rapid rotation of the outrigger legs, assisting lock-down. The pilot suggested that the right outrigger may have locked down when the load on it was briefly removed as the aircraft left the runway, due to the slight drop between the runway edge and the grass.