Abstract: A watercraft trim system having port and starboard trim flaps which mount near the stern. The trim flaps are independently operated by pneumatic operators. The pneumatic operators are governed by pressure modulators which each advantageously include a gas compressor and controllable pressure relief valve. An automatic control system is used to control the pressure modulators. The control system includes attitude sensors using optical emitter-detectors which beam across liquid-filled channels. The channels contain gas bubbles which are detected by the emitter-detectors to indicate attitude deviations.

Abstract: Apparatus for early detection of fatigue cracks in aircraft structure surrounding fasteners and the like.An ultrasonic scanner manipulating apparatus is provided with various types of replaceable tips which are used to establish the center of a given fastener, adjustable support legs which provide stability and maintain a proper distance for an ultrasonic transmitting/receiving head assembly to be rotated 360.degree. about the centerline of the fastener, and a liquid filled boot attached to the transmitting/receiving head assembly to assure a reliable signal path between the head and the structure being evaluated.