Flap Peening is also known as Roto-Peening or Flapper Peening or Rotary Flap Peening. It is a portable shot peening procedure, suitable for the confine treatment of small and difficult-to-access areas. It is mainly used by maintenance and repair professionals for aircraft and helicopters, because it permits a shot peening treatment directly on the area to be treated, without seperating the part. Flap peening can also be done in the field, making the time-consuming and expensive disassembly and transportation of elements unessential.