 The all-important 150-hour qualification test that was to have been accomplished in December 1949 was not completed until January 1951, a year behind schedule.The afterburner was particularly troublesome – the afterburning version of the engine, the J40-WE-8, did not pass its 150-hour qualification until August 1952.As a result, J40-WE-6 engines without afterburners had to be used for initial testing, causing delays in flight test programs.