CLOSED ??? I don't think so.....they want to prevent them from sticking WIDE OPEN !!
YES, STICK CLOSED!!!
The close tolerances between the butterflies and the injector hat, during idle - staging, will ice up very quickly and stick CLOSED. At wide open throttle there is very little area that has close enough tolerances to allow enough ice to form to prevent the butterflies from closing. Not saying it can't happen, but, to my knowledge, it hasn't happened to the extent of causing a major problem.
