B737-800
Flight Crew Last 90 Days 210; Flight Crew Total 25000; Flight Crew Type 5000
Training / Qualification; Situational Awareness
Aircraft Equipment Problem Critical
Flight Crew Returned To Departure Airport; General Declared Emergency
Aircraft
After departure and above the cloud deck where it is smooth my First Officer and I noticed a continuous elevator oscillation. We leveled off around 14;000 FT and oscillation stopped. We continued climb and as soon as climb power was introduced oscillation started again. This time we leveled off at FL240 and after discussion I declared an emergency and returned to the departure airport for an overweight landing.
The reporter stated that the oscillation frequency with climb power applied was about 3 'bumps' per second. In level flight at 14;000 FT the 'flutter' was absent. During climb to 24;000 FT the 'flutter' was evident again but after leveling and with the power reduction; the anomaly ceased. The 'flutter' was felt throughout the aircraft and the reporter decided it was serious enough that he returned to the departure airport. He had not heard the cause of the event; but was told that this was a repeat event with this aircraft.
A B737-800 developed an elevator flutter with a frequency of about 3 oscillations per second with climb power applied; an emergency was declared and the flight returned to the departure airport.