A319
Flight Crew Air Transport Pilot (ATP)
Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action; General Release Refused / Aircraft Not Accepted
Human Factors; Incorrect / Not Installed / Unavailable Part
After arriving at the gate; the inbound Captain informed me of a write-up regarding the flight deck door latch.  Maintenance had been contacted and were en route to correct the discrepancy.  The door was repaired and signed off by Maintenance in approximately 20 minutes.  After my First Officer's walk-around; he told me about a missing panel on the Number 1 engine. The missing panel was on the top of the cowling; outboard side; adjacent to the pylon.  I phoned Maintenance Control; and my First Officer began researching for relief in the CDL.  Neither Maintenance Control nor my First Officer found any reference to the missing panel. (We later determined the panel is known as 'The Hinge Access panel')  Maintenance Control contacted Airbus for an exemption to fly the airplane; which Airbus declined to grant.  Inspecting the engine; it was obvious that the thrust reverser was new; as was the landing gear.  Researching the logbook; we determined that the airplane had come out of a maintenance check the day prior.  We reasoned that the part had been removed during this maintenance; and most likely had not been reinstalled; as we found no evidence on the pylon or wing that the panel had departed the airplane in flight (e.g.; scratches; missing paint).  Since the maintenance [was] performed; the airplane had flown 5 legs; presumably with the missing panel. It should be noted that the missing panel was difficult to see from the ground during a walk around; especially when standing right next to the engine.  The panel was most noticeable when viewed from the jetway; not normally part of a walk around inspection.  The missing part was found that afternoon at [the maintenance facility]; and was flown to CAK on the evening flight; and installed.  The airplane was flown over 9 hours late; by a replacement crew.  I; and my crew; returned to the hotel prior to the evening flight's arrival.  We did not operate the airplane that day.  We deadheaded back the next day. The panel should have been reinstalled after the engine maintenance performed.  Other crews should have discovered this discrepancy. However; its location on the top of the engine cowling makes it difficult to see when standing next to the engine; during a walk around inspection of the airplane.  I; and specifically my first officer; were the ones to notice the discrepancy and to initiate appropriate maintenance action to correct the discrepancy properly.
A pylon panel was inadvertently left off of the aircraft following maintenance activity.  This went undetected for several cycles due to the panel's location.  Ultimately; the panel was relocated and shipped to the aircraft where it was reinstalled.