ended ▁on ▁design ▁of ▁the ▁LE M , ▁which ▁was ▁contract ed ▁to ▁Gr um man ▁A ircraft ▁Engineering . ▁ ▁By ▁January ▁ 1 9 6 4 , ▁North ▁American ▁started ▁present ing ▁Block ▁II ▁design ▁details ▁to ▁NASA . ▁Block ▁I ▁space craft ▁were ▁used ▁for ▁all ▁un cre wed ▁Sat urn ▁ 1 B ▁and ▁Sat urn ▁V ▁test ▁fl ights . ▁Initial ly ▁two ▁cre wed ▁fl ights ▁were ▁planned , ▁but ▁this ▁was ▁reduced ▁to ▁one ▁in ▁late ▁ 1 9 6 6 . ▁This ▁mission , ▁designated ▁AS - 2 0 4 ▁but ▁named ▁Apol lo ▁ 1 ▁by ▁its ▁flight ▁crew , ▁was ▁planned ▁for ▁launch ▁on ▁February ▁ 2 1 , ▁ 1 9 6 7 . ▁But ▁during ▁a ▁dress ▁re he ars al ▁for ▁the ▁launch ▁on ▁January ▁ 2 7 , ▁all ▁three ▁astr onaut s ▁( G us ▁Gr iss om , ▁Ed ▁White ▁and ▁Roger ▁Ch aff ee ) ▁were ▁killed ▁in ▁a ▁cabin ▁fire ▁which ▁revealed ▁serious ▁design , ▁construction ▁and ▁maintenance ▁short com ings ▁in ▁Block ▁I , ▁many ▁of ▁which ▁had ▁been ▁carried ▁over ▁into ▁Block ▁II ▁command ▁modules ▁being ▁built ▁at ▁the ▁time . ▁ ▁After ▁a ▁thorough ▁investigation ▁by ▁the ▁Apol lo ▁ 2 0 4 ▁Review ▁Board , ▁it ▁was ▁decided ▁to ▁terminate ▁the ▁cre wed ▁Block ▁I ▁phase ▁and ▁re define ▁Block ▁II ▁to ▁incorpor ate ▁the ▁review ▁board ' s ▁recommend ations . ▁Block ▁II ▁incorpor ated ▁a ▁re vised ▁C M