THE ATR RATED PLT SAID THAT HE WAS ON AN ILS INSTRUMENT APPROACH, IN IFR CONDITIONS, AND HAD JUST INTERCEPTED THE GLIDE SLOPE, WHEN THE ENGINE FAILED. AN EMERGENCY, OFF AIRPORT, LANDING WAS ATTEMPTED ON A LANDFILL WITH ROUGH UNSUITABLE TERRAIN. POST ACCIDENT INVESTIGATION REVEALED THAT THE TIMING GEAR HAD SHEARED.