An air carrier aircraft departed smf and developed a vibration during the post takeoff clean up. The...

Narrative:

The engine start; taxi; and takeoff were normal. As we finished cleaning up the aircraft; we heard a vibration noise. We checked the pressurization and engine instruments and everything was normal. As we climbed; the noise held steady initially. The flight attendants called to say they heard it and it seemed loudest in the aft galley. At this point; we were thinking a door seal was making the noise and we confirmed normal pressurization. We also considered that the engines were out of sync; and modulating the engines did change the tone of the noise; but didn't stop it. We checked the QRH; but found nothing that applied to our situation. At this point we discussed turning back but; given all the normal indications; we elected to continue and monitor. As the climb progressed the noise decreased appreciably. The flight attendants confirmed it was much better in the back. We leveled off and everything seemed to be ok. Later on though; the flight attendants called and said the noise had started again and they felt a vibration as well. At this point; we felt that the aircraft obviously had an issue that needed to be looked at. As all indications were still normal and we were approaching our descent; we elected to continue on to our planned destination. As we pulled the power back in the descent; the noise improved and stayed fairly quiet until we powered back up in the destination traffic pattern. By then we were pretty sure there was an engine issue even though all indications continued to be normal. Sure enough; after landing; we found damage to three fan blades in the number two engine. The only thing that made sense to us was that we'd hit a bird at some point after takeoff. I really wish we'd turned back when we noticed the noise; but the normal indications and the fact that the noise decreased significantly during the climb and level off led us to make a bad decision. I was also lulled into a false sense of security because I've had noise issues in the past that resolved during the climb; which is what I thought happened here. Evaluate the situation on its own (not on what's happened in the past) and be conservative. When we discussed turning back; we should have. Our crew communication was good; I thought; but we still made the wrong decision.

Original NASA ASRS Text

Title: An Air Carrier aircraft departed SMF and developed a vibration during the post takeoff clean up. The crew did not determine the cause until after landing at their destination where three fan blades were found damaged; presumably by a bird.

Narrative: The engine start; taxi; and takeoff were normal. As we finished cleaning up the aircraft; we heard a vibration noise. We checked the pressurization and engine instruments and everything was normal. As we climbed; the noise held steady initially. The flight attendants called to say they heard it and it seemed loudest in the aft galley. At this point; we were thinking a door seal was making the noise and we confirmed normal pressurization. We also considered that the engines were out of sync; and modulating the engines did change the tone of the noise; but didn't stop it. We checked the QRH; but found nothing that applied to our situation. At this point we discussed turning back but; given all the normal indications; we elected to continue and monitor. As the climb progressed the noise decreased appreciably. The flight attendants confirmed it was much better in the back. We leveled off and everything seemed to be OK. Later on though; the flight attendants called and said the noise had started again and they felt a vibration as well. At this point; we felt that the aircraft obviously had an issue that needed to be looked at. As all indications were still normal and we were approaching our descent; we elected to continue on to our planned destination. As we pulled the power back in the descent; the noise improved and stayed fairly quiet until we powered back up in the destination traffic pattern. By then we were pretty sure there was an engine issue even though all indications continued to be normal. Sure enough; after landing; we found damage to three fan blades in the number two engine. The only thing that made sense to us was that we'd hit a bird at some point after takeoff. I really wish we'd turned back when we noticed the noise; but the normal indications and the fact that the noise decreased significantly during the climb and level off led us to make a bad decision. I was also lulled into a false sense of security because I've had noise issues in the past that resolved during the climb; which is what I thought happened here. Evaluate the situation on its own (not on what's happened in the past) and be conservative. When we discussed turning back; we should have. Our crew communication was good; I thought; but we still made the wrong decision.

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.

Attributes
ACN	943619
Time
Date	201104
Local Time Of Day	1801-2400
Place
Locale Reference	SMF.Tower
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Person 1
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 135 Flight Crew Type 12000
Person 2
Function	First Officer Pilot Flying
Experience	Flight Crew Last 90 Days 200 Flight Crew Type 7000
Events
Anomaly	Aircraft Equipment Problem Less Severe Inflight Event / Encounter Bird / Animal

An air carrier aircraft departed smf and developed a vibration during the post takeoff clean up. The crew did not determine the cause until after landing at their destination where three fan blades were found damaged; presumably by a bird.