What happened
The flight crew encountered an electrical failure that prevented the normal extension of the landing gear. In response, they manually extended the gear and performed a temporary repair on the ground. To secure the landing gear in the down position, the pilot clamped a wrench to the landing gear strut, effectively creating a stiff-legged configuration.
Despite this improvised measure, the aircraft experienced a second collapse of the landing gear while taxiing to the active runway for takeoff or landing. The temporary repair failed during this ground movement.
The investigation
Examination of the makeshift repair revealed that the wrench used to clamp the strut had broken. Further inspection indicated that the tool appeared to have sustained previous damage prior to its use in the emergency repair, suggesting it was not suitable for the task.