Special Oilfield Services Co LLC empty tanker vehicle on its way back to Fahud base suffered major breakdown due to mechanical failure on its rear axel suspension. Why it happened/Finding : Operator of vehicle unaware of suspensions defective condition was driving vehicle at 52kmph that gave way for suspensions failure The vehicle suspensions possibly had fatigue related not picked up during inspections (Dealer/ RAS/Driver daily/ SPOT) Possibly fatigue defects developed during driving post inspection due to poor road condition. The road condition from Fahud to QarnAlam is most of the times bad which is inducing unwanted vibrations and impact Heavy vehicle drivers had no training / awareness on inspection / primary inspection requirements of heavy vehicles on load bearing critical elements RAS inspections are ineffective / inadequate to pick the fatigue related defects on load bearing elements of vehicles. Other vehicles in fleet of same configuration upon inspection found with defects of kind on their leaf springs and their assemblies