Date: 201708
Location: ZZZ.Airport, US
Aircraft: B737-700
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Reverser Lockout
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Routine Inspection
Result: General None Reported / Taken
Contributing factors: Aircraft; Procedure; Human Factors
Primary problem: Procedure

Narrative: On our originator in ZZZ; I came into the cockpit and noticed that the ground power was connected. I immediately looked in the logbook and around a bit to see if maybe Maintenance (MX) was on the aircraft. When I saw the thrust reverser deferral recently completed in the logbook; I spoke with the Agent to verify that MX was indeed recently on the aircraft and she said they had been earlier. No Maintenance was on aircraft at that point. I soon called Maintenance Control through my Dispatcher to discuss the thrust reverser MEL in the logbook. Its specific number was labeled correctly on the Release and incorrectly in the logbook. The logbook was subsequently corrected. Then I brought yet another active and incorrectly numerically labeled MEL in the logbook to attention of MX Control. This was also corrected. I expressed my concern with MX Control over Contract Maintenance performing the MEL. I specifically asked if all the Maintenance stuff/procedures were complied with. The Controller I spoke with; without hesitation; said that they had walked Contract through everything as the Contract Mechanic was a 'new' guy. It was good to go. The walk around yielded nothing irregular except the appropriate lockout pins for the number 2 thrust reverser and I even confirmed with Maintenance the difference in length of the pins. We departed ZZZ and landed in ZZZ1 uneventfully.Today; I received a phone call from my Assistant Chief Pilot in ZZZ1 and was told that the aircraft was found to have had a lockout pin installed in the wheel well. I was actually expecting a thank you for catching the two logbook errors and instead I was told that I missed something on the walk around and to [report] it. I have spoken with Maintenance Control about this today. The Controller I spoke with was extremely helpful in providing a MX diagram; but I (and maybe the other Pilots who didn't see this pin) would like to see a picture of what the thrust reverser ISO valve lockout pin looks like installed in an actual wheel well and of course at night. Did this particular pin have a flag on it? Did a Pilot find it? Was it found by Maintenance? Did Contract Maintenance in ZZZ realize they were missing a lockout pin specific to a Boeing 737 thrust reverser ISO valve? I was told that this aircraft flew for several legs after we brought it to ZZZ1. I absolutely make mistakes every day; but apparently others made the same mistake this day and it would be just awesome if we can all learn from this event rather than just fear the consequences of not submitting a [report].If Maintenance installs any pin in the aircraft; it needs to be documented in the logbook in the manner for the Pilot in Command to see its installation and subsequent removal in writing. Line Pilots do not have ready access to the 737 Maintenance manual and are forced to 'assume' that all procedures have been complied with that are Maintenance procedures and not 'visible' on the MEL information.




Synopsis: B737 Captain reported that after several flights the aircraft was found to have had a lockout pin installed in the wheel well.