EMB ERJ 145 ER/LR
Flight Crew Air Transport Pilot (ATP)
Confusion
Aircraft Equipment Problem Critical; Ground Event / Encounter FOD
Aircraft Aircraft Damaged; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft; Airport
During post/pre-flight inspection in ZZZ1; the First Officer (F/O) noticed significant FOD damage to the (Left) #1 Engine fan.  Specifically; one fan blade was bent outward about the last inch; at the tip.  Several blades had dime size pieces missing and cracks further into the fan blades.  Numerous gouges along the fan casing adjacent to the fan.  Several embedded pieces of metal shrapnel in the fan casing and acoustic lining of the inlet.  We suspect this damage occurred sometime after landing and the object was either metal or concrete.  The engine had no damage when we left ZZZ and all engine parameters were normal during the three hour flight.  We landed on Runway XXR and taxied via XX to the ramp.  We were only behind another aircraft; a B737; at the hold short for XXC and then crossing that runway and XXL; but nothing was unusual about their power settings; nor did we notice any debris flying around.  No birds were observed in flight or on the ground.  And icing was not a factor before; during; or after the flight.  No parts and panels from the airplane were missing.  After we contacted Maintenance Control; I did contact the ZZZ1 Tower via landline to inform them of the FOD damage.  About an hour after this; an Airport Operations vehicle did come to inspect the airplane; but the individual I spoke with informed me a runway and taxiway FOD sweep had not yet occurred.  In addition; an FAA Inspector from the local office called me to discuss; but left the conversation with our air-carrier programs; including the Logbook entries to be the entities to handle this event. I have no explanation as to when this damage occurred; but I am strongly assuming that it was after landing.  Considering the damage; I can't imagine this fan disk would have stayed intact at a high power setting and I am extremely grateful that I had a F/O who was doing his job and actually inspecting the airplane on his walk-around.  After the event; three things do stand out to me; considering again we do not know when this happened:  1) After notifying Maintenance Control; I was informed the plane had been involved in a bird strike the previous day; despite no entries into the Logbook. 2) Prior to the flight from ZZZ; the aircraft was with Maintenance; and according to the Logbook; Routine Checks...but could a tool have been left at the bottom of the inlet and out of sight from normal pre-flight inspection? 3) Runway XXL was closed for unknown reasons; so we could have picked up FOD there? The F/O; doing a proper walk-around inspection; saved the day on this one.  With this damage; I do think we would have had a catastrophic failure on the next flight.  From a training standpoint; I cannot stress the importance of a good walk-around. Clear; good visibility.
I performed the pre-flight inspection on the aircraft and did not notice anything unusual. The flight from ZZZ to ZZZ1 was a normal flight in VMC; and we never had any abnormal indications. We landed on Runway XXR and taxied via XX to our parking spot. We still had no abnormal indications as we shut down and prepared for the flight back to ZZZ. Upon performing the post-flight inspection; I noticed several damaged fan blades on the Number One (Left side) Engine. I notified the Captain and we both went out to take another look. He agreed that there was significant damage to the fan blades and potentially to other internal parts. We called to have Maintenance inspect the engine and informed the Company of the issue. After a brief period; the flight was cancelled and we were rescheduled to dead head to ZZZ on another flight.  The only real threat was that we had damage; that had it not been detected on the post flight; could have resulted in an engine failure on a subsequent flight. Thankfully the error was detected before any further damage could occur.
A Captain and First Officer (F/O) report finding significant F.O.D. damage to the Left Engine inlet fan blades during post flight walk-around of an EMB-145 aircraft. One fan blade was bent outward at the tip and several blades had dime size pieces missing and cracks further into the fan blades. Flight was canceled.