Bell YAH - 63 The Bell Model 409 / YAH - 63 was an experimental attack helicopter for the Advanced Attack Helicopter ( AAH ) competition . Hughes ' " Model 77 / YAH - 64 " , later developed into the AH - 64 Apache , was selected over Bell ' s entry . Design and development . During the mid - 1960s , United States Army initiated the Advanced Aerial Fire Support System ( AAFSS ) program to develop the Lockheed AH - 56 Cheyenne for the anti - tank gunship role . The U . S . Army pursued the AH - 1G HueyCobra as an interim type for the " jungle fighting " role . However the Army ' s broader concern was the task of protecting Western Europe from the legions of Warsaw Pact armor to the east . In 1972 , the Army conducted an evaluation between the Bell Model 309 KingCobra , the Lockheed Cheyenne , and the Sikorsky S - 67 in a competitive fly - off . The fly - off began in the spring of 1972 and was completed in July . In August , somewhat to everyone ' s shock , the Army rejected all three competitors . Difficulties delayed the AH - 56 Cheyenne development . The Army canceled the Cheyenne program in August 1972 . Controversy over the Cheyenne ' s role in combat and the political climate regarding military acquisition programs caused the Army to amend the service ' s attack helicopter requirements in favor of a simpler and more survivable conventional helicopter . Bell 409 . The Army sought an aircraft to fill an anti - armor attack role . The Army wanted an aircraft better than the AH - 1 Cobra in firepower , performance and range . The aircraft would have the maneuverability to fly nap - of - the - earth ( NoE ) missions . To this end the U . S . Army issued a request for proposals ( RFP ) for an Advanced Attack Helicopter ( AAH ) in 1972 . The Army specified that the AAH was to be powered by twin General Electric T700 turboshaft engines with 1 , 500 shp ( 1 , 120 kW ) each . This was the same powerplant fit specified for a new Army utility helicopter competition that would be won by the Sikorsky S - 70 Black Hawk . The AAH would be armed with a 30 millimeter cannon and sixteen BGM - 71 TOW anti - tank missiles . The missile armament specification was later modified to include an alternate load of sixteen laser - guided AGM - 114 Hellfire anti - tank missiles . Hellfire was then in development and promised greater range and lethality than TOW . Bell , Boeing - Vertol ( teamed with Grumman ) , Hughes , Lockheed , and Sikorsky all submitted proposals for the AAH program . In June 1973 Bell and Hughes were selected as finalists , and each was awarded a contract for the construction of two prototype aircraft . The Bell entry , the Model 409 ( YAH - 63 ) , was by no means " just another Cobra design " though it utilized Cobra technology where possible . Although it had what had become by then the typical configuration for a helicopter gunship , with a sharklike fuselage , tandem crew seating , and stub wings for armament , the YAH - 63 was largely a new machine . Distinctive features included wheeled tricycle landing gear , flat canopy window plates , an unusual " tee " tail , a large ventral fin , and a three - barreled General Electric XM - 188 30 millimeter cannon . The YAH - 63 ' s rotor mast could be lowered and the landing gear could kneel to reduce its height for transport . One less noticeable feature was that the pilot occupied the front seat instead of the back , the reverse of the AH - 1 ' s arrangement . This was believed to be more prudent since the YAH - 63 was intended to fly " in the treetops " during NoE operations , and the pilot needed to have a clear view of the aircraft ' s surroundings . The first prototype of the YAH - 63 ( serial 73 - 22246 ) made its initial flight on 1 October 1975 . This rotorcraft crashed in June 1976 but a static test prototype was brought up to flight standard and , along with the second prototype ( 73 - 22247 ) , entered the flyoff against the Hughes entry , the Model 77 ( YAH - 64 ) . The YAH - 64 was selected in December 1976 and was developed into the production AH - 64 Apache version . The Army believed that the YAH - 63 ' s two - blade rotor was more vulnerable to damage than the Apache ' s four - bladed rotor . In addition the service did not like the YAH - 63 ' s tricycle landing gear scheme , believing it was less stable than the Apache ' s " taildragger " configuration . Some observers also suspected the Army did not want to divert Bell from AH - 1 production . Bell would use its experience with the T700 engine to develop the AH - 1T + design and later AH - 1W .