A 737 I was supposed to fly on yesterday was grounded after, per the captain, it ingested a pebble on the taxiway causing damage to a fan blade. My question is: how did they know this happened? (Lucky for us they had a spare plane coming in right at the next gate & were able to get a full planeload of us out with only a couple hour delay.)
2 Answers
Most likely either the captain or the first officer spotted the damage during a preflight walk around of the A/C and reported it to maintenance. The flight crew deemed the damage to be a flight safety risk and that the aircraft was no longer airworthy until it could be repaired. While rare, engine damage due to FOD ingestion occasionally happens. That’s why we do preflight inspections to physically inspect the airframe, engines and other systems for any signs of damage prior to flying.
The pilot and co-pilot actually have a much better field of view than one may expect from the cock pit. Now while one of them may have seen the pebble get ingested by one of the engines this is where the facts end. But the damaged fan blade is simply an educated but more than likely correct assumption. The only way to confirm the damage though is to cut power to the engine(s) and conduct a visual inspection as well as an internal borescope inspection of the engine itself. From personal experience while working on turbofan engines for the F/A18 Hornet and Super Hornets. It's rare that you would only have damage occur to only the blades of only a single module.