B737-700
Flight Crew Last 90 Days 64
Human-Machine Interface
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
Flight Crew Overcame Equipment Problem; General Maintenance Action
Aircraft; Human Factors; Procedure
Approximately five minutes prior to the scheduled push time; I started the APU and placed the aircraft electronics on the APU generator. The APU Bleed was switched to on after operating for greater than a minute. Shortly thereafter; a Ground Crew Member asked if we had been cleared to start an engine; then stated an engine was turning; and there was no anti-collision light on. Both pilots responded 'no' to his question. I then saw the number two engine start switch was in the GND position and immediately moved it to the off position. The Ground Crew Member exited the cockpit.Maintenance had been performed on the number two thrust reverser prior to the arrival of the originating flight crew. Both pilots reviewed the preflight flows in the AOM; but found no requirement for either pilot to ensure the correct position of the start switches prior to starting and using the APU. I could find no requirement for checking the position of the start switches until the after engine start flows.
Maintenance personnel failed to ensure the right engine start switch was correctly positioned after performing maintenance on the thrust reverser. The engine began to motor when the First Officer started the APU and opened the APU bleed five minutes prior to scheduled departure.