What was found
AIR TURNBACK AFTER CLIMBING THROUGH 24K FT CAS FAILED, SHORTLY AFTER LEVEL AT 33K BOTH TRANSPONDERS FAILED, 10 MIN LATER AUTO PRESS FAILED, LOW IDLE UPON DESCENT. AIRCRAFT MADE AN UNEVENTFUL LANDING. REMOVED AND REPLACED R3 TRANSFER RELAY PER BOEING MM. OPS CHECK NORMAL. (LPG 71230)