What was found
DURING CRUISE AT FL290, CABIN ALT STARTED TO CLIMB, RT PACK PRESS BEGAN OSCILLATING, FLOW LIGHT ILLUMINATED, PERFORMED QRH PROCEDURE AND BEGAN AND EMERGENCY DECENT. TROUBLE SHOT SYSTEM TO A DEFECTIVE RIGHT COOLING TURBINE. REMOVED AND REPLACED RT COOLING TURBINE IAW AMM 21-51-01 OPS REVEALED LOW AIR FLOW. REMOVED AND REPLACED RIGHT COOLING FAN IAW AMM 21-51-01 LEAK CHECK AND OPS CHECK IAW AMM 21-00-00. NO LEAKS NOTED OPS CK NORMAL AT THIS TIME.