Arun Kumar Singh, former chairman of oil refining and marketing company BPCL, was on Wednesday appointed chairman and managing director of ONGC — the first instance of a retired person being appointed the head of a Maharatna PSU. “The Appointments Committee of Cabinet (ACC) has approved the proposal of Ministry of Petroleum and Natural Gas for appointment of Arun Kumar Singh, ex-CMD, BPCL as Chairman, ONGC for a three-year tenure with effect from the date of his assumption of charge of the post,” an official order said.