What was found
DURING CRUISE RETURNING TO BASE, WHEN THE NR 2 RADIAL ENGINE REAR SUMP METAL CONTAMINATION LIGHT ILLUMINATED, FOLLOWED BY A DEGRADATION OF TORQUE REQUIRING ADDITIONAL MANIFOLD PRESSURE TO MAINTAIN CRUISE POWER, WHITE SMOKE OBSERVED FROM THE INBD POWER RECOVERY TURBINE PRT. THE ENGINE WAS SECURED AND THE ACFT RETURNED TO BASE WITHOUT INCIDENT. AN EMERGENCY WAS NOT DECLARED. DURING INVESTIGATION, IT WAS DETERMINED THAT THE NR 3 PRT FAILED CAUSING OIL SYSTEM CONTAMINATION.