 These first production Demons were grounded for a redesign to accept the J71 engine after the loss of six aircraft and four pilots.The decision to move the Demon to the J71 had occurred long before the initial production batch emerged and with the development of a suitable afterburner for the J71 being protracted, BuAer decided to accept the early aircraft with Westinghouse J40-WE-22A and -22 engines.This decision came under Congressional review in 1955 and drew sharp criticism from Congress.