The three - inch ( 8 cm ) - thick resin lining protecting the rocket nozzle was found to have burned down to as little as 5 millimetres ( 0.20 in ) in places .
The rocket nozzle was designed to erode about half its thickness during firing .
The three - inch ( 8 cm ) - thick resin lining protecting the rocket nozzle , which was designed to erode about half its thickness during firing , was found to have burned down to as little as 5 millimetres ( 0.20 in ) in places .