Seven months ago William Averell Har- riman. then board chairman of potent Aviation Corp.. was persuaded to invite Motormaker Errett Lobban Cord into the directorate of Avco. Mr. Cord had been a painful nuisance to Avco and other ''pioneer'' operators with his low-fare Century Air Lines, his rambunctious efforts in Washington to get mail contracts. Avco took over Century, gave Mr. Cord 5% of the Corporation's stock. There were expressions of esteem on both sides. But the industry, aware of Mr. Cord as a shrewd, aggressive operator, accustomed to running things his own...

