Tiger props are commonly installed improperly when the rear bulkhead is allowed to drop out of alignment while tightening the bolts. The crank bushings cookie cut crescent shaped slivers of aluminum and wedge them between the flywheel and the prop spacer not allowing a proper or parallel seat. Over time, as the prop operates, these slivers of aluminum crush thinner loosening the torque on the prop bolts. Loose bolts stretch, loosening further, until they fail domino-ing all the bolts and the prop separates from the airplane. The maintenance manual cautions about this and recommends taping the bulkhead in place while the bolts are tightened. Longer crank bushings can also be installed preventing this problem.