John, you are correct. A jet engine is designed for intake of air through the Impellers, Air ONLY. not screws, bolts nuts, or anything else. If a hard metal,plastic, or foreign material enters the impellers, it will fracture then shatter the others, which causes a rapid stop to the function of the impellers. The engine will shut down or implode. Nothing but AIR is to be ingested into any jet engine. I have worked on B-52's and KC-135's, and I believe this to be a true statement. Look at prop driven aircraft. Throw a bolt in the propeller , what happens?
Damage to the prop, which creates unbalance, which creates damage to the crankshaft, bearings, valves etc. That also will cause shutdown in certain cases. Birds, are also a problem near Airports, and have caused many aircraft to make emergency landings as you are aware of. To many uneducated wanna be pilots are buying these "Drone" Quad Copters without knowing the responsibility they are undertaking. This has become a very serious problem for the FAA and the AMA, but it continues. Once a serious accident happens, LOOK OUT!