The advantage of having the engines on the sides of the helicopter (instead on being burried in the helicopter airframe) which most modern attack helicopters do have (such as the Apache) is that it makes an impact from a MANPADS heat seeking missile less catastrophic since heat seeking missiles trend to follow the engine exausts (the hotest part of an aircraft). So if the helicopter has it's engines located in the sides of the helicopters chances are that only the one engine is destroyed/damaged in case of an impact but if the helicopter have it's engines burried in the airframe (such as in the Hind) chances are that more things gets destroyed (such as main rotor and other stuff) thus making a catatrophic damage much more likelly.