Narrative:

Climbing through 7;500 ft MSL to a cruising altitude of 10;000 ft MSL; the aircraft experienced a violent vibration. The pilot flying was hand flying the aircraft to the cruise altitude when the event occurred. Myself and the first officer evaluated the situation and came to the conclusion that this was a flight control surface issue. I instructed the first officer to look out his window toward the right aileron and tell me what he saw. He informed me that the control surface looked normal. When I did the same I saw what appeared to be the left aileron and static wicks vibrating. This caused me concern to the structural integrity of the aircraft and flight control surfaces. At the time the aircraft was leveling off at 10;000 ft and the autopilot was engaged. I made the decision to contact the company and let them know of the situation. The first officer stayed with approach and continued to fly the aircraft. After about two minutes we both came to the conclusion this problem was not getting better and safety may be compromised. We made the decision to divert the aircraft for a precautionary landing. At this time I instructed the first officer to disconnect the autopilot and hand fly the decent and approach to the airport. During the approach and the introduction of flaps 15 degrees setting the aircraft vibrations began to intensify. I noticed on short final the left engine oil pressure fluctuated around 5%. We made the decision to land the aircraft with only 15 degrees of flaps for fear that even more would worsen the stability of the approach. The aircraft landed without incident and we taxied to the gate.

Google
 

Original NASA ASRS Text

Title: SF340 flight crew during climb reported a significant vibration; flight control surfaces were questionable in the crew's opinion. They elected to divert to an enroute airport and on final noticed the left engine oil pressure was low.

Narrative: Climbing through 7;500 FT MSL to a cruising altitude of 10;000 FT MSL; the aircraft experienced a violent vibration. The pilot flying was hand flying the aircraft to the cruise altitude when the event occurred. Myself and the First Officer evaluated the situation and came to the conclusion that this was a flight control surface issue. I instructed the First Officer to look out his window toward the right aileron and tell me what he saw. He informed me that the control surface looked normal. When I did the same I saw what appeared to be the left aileron and static wicks vibrating. This caused me concern to the structural integrity of the aircraft and flight control surfaces. At the time the aircraft was leveling off at 10;000 FT and the autopilot was engaged. I made the decision to contact the company and let them know of the situation. The First Officer stayed with Approach and continued to fly the aircraft. After about two minutes we both came to the conclusion this problem was not getting better and safety may be compromised. We made the decision to divert the aircraft for a precautionary landing. At this time I instructed the First Officer to disconnect the autopilot and hand fly the decent and approach to the airport. During the approach and the introduction of Flaps 15 degrees setting the aircraft vibrations began to intensify. I noticed on short final the left engine oil pressure fluctuated around 5%. We made the decision to land the aircraft with only 15 degrees of flaps for fear that even more would worsen the stability of the approach. The aircraft landed without incident and we taxied to the gate.

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.