Narrative:

All checklists complete; I began the takeoff roll and rotated the aircraft at the appropriate speed. After retracting the landing gear; I was immediately 'on instruments' due to the low overcast conditions. I knew I would be 'on top' by 2;500 ft MSL or so given my recent ILS approach on the previous leg. As I was flying the departure climb; I noticed several irregularities: 1) the altimeter was 'bouncing' vs. The normal 'scrolling' or smooth turning action of the hands. 2) the vertical speed indicator was also 'bouncing' vs. The normal action of pointing to the actual vertical speed of the aircraft. 3) the yoke felt like it was buffeting. Almost like a stall buffet. I kept the aircraft under control until I was on top of the clouds. I delayed completion of the after takeoff checklist until that time; so that I could dedicate my entire focus to flying the assigned heading and keeping the aircraft at an appropriate and safe indicated airspeed. Once out of the clouds; I completed the after takeoff checklist and engaged the autopilot. I was given subsequent climb from 4;000 ft to 5;000 ft. The buffet and airspeed/altimeter abnormalities were still occurring and I was looking for the reason why. At that point; I began looking out the windows of the aircraft to see if anything looked weird. It was then that I noticed the right flap vibrating. Immediately I slowed the aircraft's airspeed and considered returning back. I was then faced with two decisions. 1) return to the departure airport for a no-flap ILS to 400 ft overcast conditions with an altimeter and vsi that were bouncing. 2) continue to my destination where the weather was cavu and I could land visually. Runway length at both airports was not a factor even with the added distance from a no-flap approach and landing. Both airports had runways over 9;000 ft long. Well over 2x the calculated landing distance given weight and temperature. I had decided to land (at either airport) no-flap; because with the flap vibrating I did not want to take a chance that it was only secured to the aircraft because the flaps were 'up'; and that by selecting approach or landing flaps; the flight control would depart the aircraft partially or completely; changing the situation from an abnormal to a true emergency. At that point I decided that at 400 ft overcast; it was pretty likely that I would get in and I could almost omit the altimeter from my scan if it got too bad; using the glide slope and localizer as primary instruments along with airspeed. Once my decision was made; I notified ATC that I was going to return. They asked for the reason so they could 'tell the sup' (supervisor?) and I informed them. I included in the same radio transmission that I did not need assistance at this time but if that changed I would notify them immediately. I also told them that I was going to have to slow the aircraft early to get the gear down and that I was most likely going to need extra time on the runway due to no flaps and an increased landing roll. Once cleared for the ILS; I was handed off to tower and I repeated my request for extra time on the runway due to no flaps. I asked to exit at a taxiway far down the runway and the tower controller assured me that the whole runway was mine. I landed uneventfully; taxied in and contacted operations and maintenance. After the conversation with maintenance I exited the aircraft and attempted to 'wiggle' the flaps both left and right while they were still 'up.' there was significant movement in the right flap; but I could not be certain that the left flap didn't have the same or similar movement. I completed a post-flight inspection of the aircraft; notified the chief pilot and awaited instructions from airline operations.

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Original NASA ASRS Text

Title: Baron 58 pilot reported after takeoff he noticed airframe buffeting that he traced to vibration in the right trailing edge flap. He returned to departure airport for a zero flap approach.

Narrative: All checklists complete; I began the takeoff roll and rotated the aircraft at the appropriate speed. After retracting the landing gear; I was immediately 'on instruments' due to the low overcast conditions. I knew I would be 'on top' by 2;500 FT MSL or so given my recent ILS approach on the previous leg. As I was flying the departure climb; I noticed several irregularities: 1) The altimeter was 'bouncing' vs. the normal 'scrolling' or smooth turning action of the hands. 2) The vertical speed indicator was also 'bouncing' vs. the normal action of pointing to the actual vertical speed of the aircraft. 3) The yoke felt like it was buffeting. Almost like a stall buffet. I kept the aircraft under control until I was on top of the clouds. I delayed completion of the after takeoff checklist until that time; so that I could dedicate my entire focus to flying the assigned heading and keeping the aircraft at an appropriate and safe indicated airspeed. Once out of the clouds; I completed the after takeoff checklist and engaged the autopilot. I was given subsequent climb from 4;000 FT to 5;000 FT. The buffet and airspeed/altimeter abnormalities were still occurring and I was looking for the reason why. At that point; I began looking out the windows of the aircraft to see if anything looked weird. It was then that I noticed the right flap vibrating. Immediately I slowed the aircraft's airspeed and considered returning back. I was then faced with two decisions. 1) Return to the departure airport for a no-flap ILS to 400 FT overcast conditions with an altimeter and VSI that were bouncing. 2) Continue to my destination where the weather was CAVU and I could land visually. Runway length at both airports was not a factor even with the added distance from a no-flap approach and landing. Both airports had runways over 9;000 FT long. Well over 2x the calculated landing distance given weight and temperature. I had decided to land (at either airport) no-flap; because with the flap vibrating I did not want to take a chance that it was only secured to the aircraft because the flaps were 'up'; and that by selecting approach or landing flaps; the flight control would depart the aircraft partially or completely; changing the situation from an abnormal to a true emergency. At that point I decided that at 400 FT overcast; it was pretty likely that I would get in and I could almost omit the altimeter from my scan if it got too bad; using the glide slope and localizer as primary instruments along with airspeed. Once my decision was made; I notified ATC that I was going to return. They asked for the reason so they could 'tell the sup' (supervisor?) and I informed them. I included in the same radio transmission that I did not need assistance at this time but if that changed I would notify them immediately. I also told them that I was going to have to slow the aircraft early to get the gear down and that I was most likely going to need extra time on the runway due to no flaps and an increased landing roll. Once cleared for the ILS; I was handed off to Tower and I repeated my request for extra time on the runway due to no flaps. I asked to exit at a taxiway far down the runway and the Tower Controller assured me that the whole runway was mine. I landed uneventfully; taxied in and contacted Operations and Maintenance. After the conversation with Maintenance I exited the aircraft and attempted to 'wiggle' the flaps both left and right while they were still 'up.' There was significant movement in the right flap; but I could not be certain that the left flap didn't have the same or similar movement. I completed a post-flight inspection of the aircraft; notified the Chief Pilot and awaited instructions from airline operations.

Data retrieved from NASA's ASRS site as of July 2013 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.