Aircraft tragedy

The Concorde aircraft tragedy in July 1999 involved a fuel tank puncture caused by tire failure.During the investigation, it was disclosed that there had been at least five previous incidents of almost the same scenario. In one of the previous incidents, a tire failed and punctured the fuel tanks, yet there was no ignition. The incident investigation management systems used by the airlines failed to adequately follow-up and apply lessons learned from previous investigations. 

During the late 1980s two air tragedies resulted from very similar common cause failures. In both cases (a Japan Air Lines Boeing 747 and a United Airlines DC-10), hydraulic control was lost when the redundant hydraulic systems (seven in the 747 and three in the DC-10) were disabled by loss of hydraulic fluid when the hydraulic lines in the rudder of the aircraft were severed. Only one hydraulic system in either aircraft would have been sufficient to maintain control of the aircraft. The only location on either aircraft where all the hydraulic lines were in close proximity was in the rudder. Even though the trigger event was different for each aircraft (aft pressure bulkhead failure and sudden depressurization in the 747 and an engine explosion in the DC-10), both aircraft crashed due to common cause failure of redundant hydraulic control systems. 

Aircraft maintenance. Despite the intense media coverage of air tragedies, flying remains the safest mode of transportation by far. The reliability and safety record of aircraft operators is indeed enviable by most industrial standards. This success is directly attributable to the fact that modem aircraft maintenance practices are far removed from reliance on retroactive corrective procedures. Other industries can leam several valuable lessons from current aircraft maintenance methodologies. 

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