Flexible guide rail system, comprising a) Two rails, b) two support beams and c) a trolley, wherein each rail • is bendable in only one direction perpendicular to its longitudinal extend and • comprises a guiding-length-section with an at least partially ferromagnetic running surface, wherein each support beam comprises • two attachment regions located in a scanning distance from each other, wherein each of the attachment regions is for supporting one enc of one rail, and wherein the trolley comprises a bridge, two supporting boxes and a platform • wherein the bridge connects two supporting boxes which are arranged in the scanning distance from each other, and • wherein the platform is guided by the bridge and is movable along the bridge and • whereby each of the two supporting boxes is equipped with two wheels arranged behind each other, • wherein the wheels comprise a permanent magnetic material such that the rails and/or the support beams can be attached to an inspection surface and that the rails allow the trolley to follow the inspection surface in a controlled and guided motion once its wheels are placed on the rails, wherein the inspection surface is preferably a section of an aircraft structure made of a non-ferromagnetic material such as aluminium or composite which can be curved. a) Two rails, b) two support beams and c) a trolley, wherein each rail • is bendable in only one direction perpendicular to its longitudinal extend and • comprises a guiding-length-section with an at least partially ferromagnetic running surface, wherein each support beam comprises • two attachment regions located in a scanning distance from each other, wherein each of the attachment regions is for supporting one enc of one rail, and wherein the trolley comprises a bridge, two supporting boxes and a platform • wherein the bridge connects two supporting boxes which are arranged in the scanning distance from each other, and • wherein the platform is guided by the bridge and is movable along the bridge and • whereby each of the two supporting boxes is equipped with two wheels arranged behind each other, • wherein the wheels comprise a permanent magnetic material such that the rails and/or the support beams can be attached to an inspection surface and that the rails allow the trolley to follow the inspection surface in a controlled and guided motion once its wheels are placed on the rails, wherein the inspection surface is preferably a section of an aircraft structure made of a non-ferromagnetic material such as aluminium or composite which can be curved. wherein each rail • is bendable in only one direction perpendicular to its longitudinal extend and • comprises a guiding-length-section with an at least partially ferromagnetic running surface, • is bendable in only one direction perpendicular to its longitudinal extend and • comprises a guiding-length-section with an at least partially ferromagnetic running surface, wherein each support beam comprises • two attachment regions located in a scanning distance from each other, wherein each of the attachment regions is for supporting one enc of one rail, and • two attachment regions located in a scanning distance from each other, wherein each of the attachment regions is for supporting one enc of one rail, and wherein the trolley comprises a bridge, two supporting boxes and a platform • wherein the bridge connects two supporting boxes which are arranged in the scanning distance from each other, and • wherein the platform is guided by the bridge and is movable along the bridge and • whereby each of the two supporting boxes is equipped with two wheels arranged behind each other, • wherein the wheels comprise a permanent magnetic material such that the rails and/or the support beams can be attached to an inspection surface and that the rails allow the trolley to follow the inspection surface in a controlled and guided motion once its wheels are placed on the rails, wherein the inspection surface is preferably a section of an aircraft structure made of a non-ferromagnetic material such as aluminium or composite which can be curved. • wherein the bridge connects two supporting boxes which are arranged in the scanning distance from each other, and • wherein the platform is guided by the bridge and is movable along the bridge and • whereby each of the two supporting boxes is equipped with two wheels arranged behind each other, • wherein the wheels comprise a permanent magnetic material such that the rails and/or the support beams can be attached to an inspection surface and that the rails allow the trolley to follow the inspection surface in a controlled and guided motion once its wheels are placed on the rails, wherein the inspection surface is preferably a section of an aircraft structure made of a non-ferromagnetic material such as aluminium or composite which can be curved.