National flag carrying airline Pakistan International Airlines (PIA) has grounded one of two leased Boeing 747 aircrafts that merely needs a tyre change. Despite grounding the aircraft, PIA is paying thousands of dollars a day to the leasing company. Sources said PIA paid an advance of $ 1.125 million for two leased old series Boeing 747 aircrafts which were developing frequent faults. Sources said the Civil Aviation Authority issued clearance to the said aircrafts despite safety concerns due to pressure by the PIA administration. Sources said the aircrafts had been leased from a lesser-known airline Ballenic Aviation.