NAVIGATIONAL AIDS-NAMELY, LORAN RECEIVERS, RADAR SETS, COMPASSES, GYROCOMPASSES, AND PLATFORMS; AUTOMATIC AIRCRAFT STABILIZERS AND PILOTS AND PARTS THEREOF-NAMELY, DIRECTIONAL GYROSCOPES, VERTICAL GYROSCOPES, RATE GYROSCOPES, ACCELEROMETERS, RADIO COUPLERS, SIGNAL GENERATORS, AMPLIFIERS, COMPUTERS, SERVOMOTORS AND CONTROLS; AIRCRAFT FLIGHTT INSTRUMENTS-NAMELY, ARTIFICIAL HORIZONS, ATTITUDE INSTRUMENTS, ATTITUDE DIRECTOR INSTRUMENTS.ALTIMETERS, HORIZONTAL SITUATION DISPLAY INSTRUMENTS, AND CONTROLS FOR SAID INSTRUMENTS; COMPUTERS-NAMELY, ANALOG AND DIGITALCOMPUTERS; AIRCRAFT SPEED CONTROLS; SONAR EQUIPMENT-NAMELY, DOPPLER NAVIGATORS, SPEED LOGS, AND ECHO SOUNDERS; AUTOMATIC DIRECTION FINDERS COLLISION WARNING AND/OR NAVIGATIONAL ASSESSMENT SYSTEM, AS A NAVIGATIONAL AID MAGNETOMETERS; LASER TUBES AND COMPONENTS,INSTRUMENTS EMPLOYING LASERS-NAMELY, RING LASERS AND HEIGHT MEASURING DEVICES; TEST SETS-NAMELY, ENGINE ANALYZERS, DADAR PERFORMANCE ANALYZERS, COMPASS SWINGINGEQUIPMENT AND TEST SETS SPECIFICALLY DESIGNED FOR CHECKING ASSEMBLIES OF THE FOREGOING PARTS, AND PARTS FOR ALL OF THE FORE GOING