Bell will be using four test aircrafts in order to certify the 525 Relentless. The program had been on a hold since July 6, when the first prototype crashed, killing both test pilots. Bell has been working tirelessly on modifying the test aircrafts, to ensure that it meets certification levels from Canada, Europe and the US. They have installed software updates to the 525, upgrading the Garmin G500H avionics and fly by wire system, reports AIN Online.