Beech 1900
Flight Crew Air Transport Pilot (ATP)
Other / Unknown
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Procedure
I was the First Officer for roundtrip flights. Prior to operating the roundtrip; I was the Captain on the inbound flight that arrived 38 minutes prior to the departure of the roundtrip. As I got to the aircraft; the Captain was already doing the preflight walk-around. We finished the rest of our preflight duties and departed on time. In the turn around station; I did the post-flight walk-around and found no discrepancies. Back in original airport; I once again did the walk-around in the late afternoon. Once again; I found no discrepancies. Sunset was approaching and light was waning; but not so much as to need a flashlight. I do distinctly remember looking in the engine inlets during both of the walk-arounds I performed. The next day I was notified of the inlet plugs that had been found in the engine that morning. I was not there in the morning to know what events lead up to the plugs being sucked into the engine. That would be the first place to try to find a cause and preventative recourse. I'm not sure if I didn't look close enough in the inlets; or if the plugs were not in sight. I do believe that if the plugs were brightly colored; they would have not been missed on at least 6 different walk-arounds by 4 different people.
A BE-1900 First Officer reported doing several preflight walk-arounds; including looking in the engine inlets; and not seeing inlet covers which had been ingested during that aircraft's first start at the originating station.