A wall climbing robot has several applications in the present scenario. some of them include surface crack detection, wall surface cleaning, spray painting, etc. for that, the robot has to move on large structures which are hardly accessible otherwise. various robots have been developed that climb flat vertical surfaces using suction, magnets and adhesive materials. these mechanisms have only a small load bearing capacity and the motion over the wall surface is slow. to overcome these drawbacks, in this project we introduce a duct fan based wall climbing robot for the crack inspection on concrete wall surfaces. the thrust force provided by the duct fan holds the robot on to the wall. this thrust can be adjusted to hold the robot to different types of wall surfaces too. this wireless robot can be moved like a 4 wheeled vehicle on the wall. a camera mounted on the robot captures video of the wall under inspection. percolation method of image processing is used for detecting cracks from the video wirelessly transmitted by the camera and saved on a laptop. the mounting mechanism of the wireless camera can be modified to accommodate for spray painting, inspection, surface cleaning etc.