Narrative:

Shortly after starter cutout during push back; the tug driver informed me that the safety monitor noted a spark in the number two engine. The engine had not reached 25% prior to me lighting it off; but had stabilized at max motoring around 22.5% and all start parameters were well within normal limitations throughout rollback; including starter cutout. I asked him to find out what he had seen and understood him to say that the safety monitor had noted a spark near the bottom of the engine. I considered the normal start and told the push back crew that he probably saw the igniters in operation. After start of the number one engine; I compared the engine parameters and noted that both engines were operating normally. During taxi and run up; the engine parameters remained normal. I elected to continue the takeoff and the flight was uneventful. Enroute I started to question my decision and began to think that maybe the starter might be about to fail and this could have been the cause of the ramper's concern. When we landed; I called maintenance out to take a look. When we tried to start the number two; it did not rotate. They replaced the starter and we continued on. In hindsight; I tried to determine what led me to not properly consider the safety observer concern. I am normally very cautious; and have always previously investigated the ground crews concerns. Was it the last day of a four-day; let's get home syndrome? No; I didn't feel rushed. We were duty rigged that day and I actually could have used the additional time if we were late. Was it the fact that we were not a maintenance base? I don't think so; that's never stopped me before. I have investigated numerous things noted by the ground crew and most; if not all; have been nothing. Maybe that's it. I had begun to take them for granted. Regardless of the reason; I rank this up there as the worst decision of my career. Trust your ground crew. That's what they are there for. This event ended without incident; the next may not.

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Original NASA ASRS Text

Title: B737 Captain was informed of sparks coming from bottom of engine during starting by ground observer. Engine started normally and flight departed. Upon next start attempt starter was found to have failed.

Narrative: Shortly after starter cutout during push back; the Tug Driver informed me that the safety monitor noted a spark in the number two engine. The engine had not reached 25% prior to me lighting it off; but had stabilized at max motoring around 22.5% and all start parameters were well within normal limitations throughout rollback; including starter cutout. I asked him to find out what he had seen and understood him to say that the safety monitor had noted a spark near the bottom of the engine. I considered the normal start and told the Push back Crew that he probably saw the igniters in operation. After start of the number one engine; I compared the engine parameters and noted that both engines were operating normally. During taxi and run up; the engine parameters remained normal. I elected to continue the takeoff and the flight was uneventful. Enroute I started to question my decision and began to think that maybe the starter might be about to fail and this could have been the cause of the Ramper's concern. When we landed; I called Maintenance out to take a look. When we tried to start the number two; it did not rotate. They replaced the starter and we continued on. In hindsight; I tried to determine what led me to not properly consider the safety observer concern. I am normally very cautious; and have always previously investigated the ground crews concerns. Was it the last day of a four-day; let's get home syndrome? No; I didn't feel rushed. We were duty rigged that day and I actually could have used the additional time if we were late. Was it the fact that we were not a Maintenance Base? I don't think so; that's never stopped me before. I have investigated numerous things noted by the ground crew and most; if not all; have been nothing. Maybe that's it. I had begun to take them for granted. Regardless of the reason; I rank this up there as the worst decision of my career. Trust your ground crew. That's what they are there for. This event ended without incident; the next may not.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.