Shuttle RCC panels (22 panels together) were used on shuttle wing leading edge, nose cone, 0.25-0.5 inch thick and tough like concrete. link https://www.nasa.gov/centers/kennedy/pdf/167473main_TPS-06rev.pdf . Article pages 5-6 states that after each flight they went through three kind of simple inspections and if any damage was found they were removed and returned to the vendor for repair and refurbishment. Article doesn't specify how often must be replaced, but say that after specified number of mission they were sent back to the vendor for re-coating (or in other worlds needed surface treatment). During processing for return to flight, all RCC panels underwent extensive nondestructive inspections (NDI) and nondestructive evaluations (NDE). NDI inspections included the use of thermography and a CAT scan to detect imperfections or cracks in the structures on and below the surface. NDE methods included eddy current, ultrasound and X-ray inspections. In addition, several inspections of the metal components behind the RCC panels were performed.
So did anybody here know how often any of those 22 panels:
- Were damaged during the flight and then must be replaced, repair?
- After what exact number of specified mission (3,5,10, more) they were sent back to vendor for re-coating - needed surface treatment?
- Were all those inspections necessary, how expansive they were?
- Were they necessary during all existence of Shuttle or only after Columbia disaster?