What happened
On August 2, 2008, a Piper PA38-112, registration OK-IWB, was performing a solo flight at Zbraslavice aerodrome. The flight originated from Roudnice nad Labem, where the pilot had previously completed training maneuvers.
During the landing phase at Zbraslavice, the aircraft experienced a sudden nose-down pitch. The pilot reported that while in the transition flare, the flaps spontaneously retracted from position '2' to position '1'. At the moment of this change, the aircraft was traveling at approximately 70 knots. The pilot attempted to recover by applying full power and pulling back on the control column, but the attempt was unsuccessful. Consequently, the pilot executed a run-off from the runway, eventually bringing the aircraft to a stop and shutting down the engine.
Upon impact with the ground, the nose gear collapsed, causing damage to the fuselage skin near the nose gear strut attachment. The impact also resulted in visible movement of the engine assembly and damage to the engine mount reinforcement. No injuries were reported, though the aircraft sustained significant damage.
The investigation
The ÚZPLN investigation focused on the mechanical integrity of the flap control system and the physical environment of the cockpit. Investigators examined the flap control mechanism, which utilizes a direct mechanical linkage with a spring-loaded ratchet system.
Technical inspections of the flap control system were conducted by a maintenance organization. The investigation found that the control mechanism itself was functioning correctly and showed no signs of mechanical failure. The investigators also noted that the aircraft's maintenance history included a previous report regarding difficulty disengaging the flaps from the maximum position, which had been addressed via lubrication and inspection of the locking mechanism.
Findings
- The investigation could not definitively identify a mechanical failure within the flap control system.
- The pilot's physical build was noted; specifically, the pilot's right leg was in close proximity to the flap control lever when seated in the left seat.
- The flap control lever may have been physically obstructed by the pilot's leg, potentially preventing the lever from being properly secured in position '2'.
- The spontaneous retraction of the flaps from position '2' to position '1' was the primary factor leading to the loss of lift and subsequent nose gear collapse.