Date: 201402
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Dawn
Aircraft: Beech 1900
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
ATC / advisory: Ramp ZZZ
Aircraft component: Cowling
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Commercial
Human factors: Other / Unknown; Fatigue; Communication Breakdown
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Aircraft In Service At Gate
Result: General None Reported / Taken
Contributing factors: Aircraft; Procedure
Primary problem: Procedure

Narrative: It was brought to my attention that an incident had occurred where the engine inlet covers had been ingested into the engines. That morning I did the preflight inspection and noted the covers but had been under the impression they were there to keep the engines warm and would be removed prior to the flight by the ground crew. Upon my post-flight inspection in that first destination I did not notice these covers in the engine inlet. The only explanation I can think of is that the inlets are similar to pillows and may have been very compressed and had not re-inflated yet and were therefore not very visible. In addition they are the same color of the inlet and depending on their location at the time; may not have been visible. During the engine startup and throughout the flight; no abnormal indications were noted in performance or engine temperature that would have given reason to believe anything out of the usual had occurred. This event was discovered to have occurred after maintenance personal identified the inlet covers on the following morning during their daily RON checks. This event occurred during the first flight of the day. Individuals involved were the ground crew in the originating station for their lack of properly removing the inlet covers and myself and the Captain for not finding the covers during the post-flight inspection upon completion of our flight.Ground agents should have their own checklists for making sure their tasks are complete. As well as improved awareness during startup to notice the covers had not been removed. Also the inlet plugs could be colored red instead of silver making them highly visible instead of the same color of the intake.

Callback: The reporter stated that the inlet cowling plugs are a gray colored; soft foamy material which custom fit the inlet cowl. He saw the covers in the soft dawn light but assumed that a ramp person would remove them before start; but that did not happen. Anyone conducting a preflight walk-around after the covers were ingested would not see them in the let because both were sucked down and wedged near the separator baffle. They could not have been sucked completely through the engine because the air goes forward; makes a 180 degree turn and the reporter believes it would be nearly impossible to make the trip into the compressor blades. His Company is changing procedures which require cover removal during preflight and the covers will be colored so they stand out and are distinguishable from the surrounding engine.



Synopsis: A BE-1900 First Officer noted the engine inlet covers during his early morning preflight and assumed the ground crew would remove them but was told later that the engines were run all day after ingesting the covers during start that morning.