THE PILOT INITIATING VFR FLIGHT INTO INSTRUMENT METEOROLOGICAL CONDITIONS RESULTING IN SPATIAL DISORIENTATION AND LOSS OF AIRCRAFT CONTROL. DURING HIS ATTEMPT TO REGAIN CONTROL OF THE AIRCRAFT THE PILOT EXCEEDED THE DESIGN STRESS LIMITS RESULTING IN WING OVERLOAD AND SEPARATION. FACTORS WHICH CONTRIBUTED TO THE ACCIDENT WERE: THE PILOT'S DISREGARD OF THE WEATHER BRIEFER'S ADVISORY THAT VFR FLIGHT WAS NOT RECOMMENDED, THE WEATHER CONDITIONS, THE DARK NIGHT, AND THE PILOT'S LACK OF INSTRUMENT TIME AND NIGHT FLYING EXPERIENCE.