A cover assembly for an air cushion restraint has a smooth cover with a layer of foam connected between the cover and a load bearing insert for covering a housing for an airbag and a gas generator which generates an inflatant for the airbag for deploying the airbag; three cutters are pivotally connected to the insert member to cut an insert cover member from the insert and to pierce the smooth outer cover member during inflation of the airbag so as to form a self-piercing cover assembly which will be cut to form a three sided opening through the cover assembly through which the airbag is deployed; the cutters are actuated by an insert cover member support system which will operate the cutters as the airbag is inflated to cause cutting edges on the cutters to pierce the smooth outer cover member. The cutters are recessed within the cover assembly to avoid incidental contact with the cutting edges prior to deployment. The cutters are configured such that on deployment the cutting edges have only a limited entry into the passenger compartment of a vehicle. The cutters are arranged to self-retract following airbag deployment to shield the cutting edges from passenger contact during secondary impacts.