CHI99IA115

On two separate flights, the flight crews determined that the elevator would not respond to control input. During the first occurrence, the flight crew continued to fly the airplane using pitch trim and descended to a lower altitude where elevator control returned. During the second occurrence, the flight crew applied elevator backpressure until the elevator '...bump[ed} free and control was restored.' After the first occurrence, maintenance personnel found ice accretions in the elevator control bay of the vertical stabilizer. They also found debris obstructing the drain holes in this area. Maintenance personnel were unable to find any anomalies after the second occurrence. On both occasions, the airplane departed in rain showers with surface temperatures of 46 degrees (F) and 39 degrees (F) respectively.

On March 21, 1999, at 1945 central standard time (cst), a McDonnell Douglas DC-9-14, N600ME, operated by Midwest Express Airlines (MWEA), Inc., experienced a loss of elevator control while in cruise flight over Grand Rapids, Michigan. The 14 CFR Part 121 flight departed Newark International Airport (EWR), Newark, New Jersey, en route to General Mitchell International Airport (MKE), Milwaukee, Wisconsin. The flight crew piloted the aircraft using the elevator trim system until regaining elevator control after descent. The airplane landed at General Mitchell International Airport without further incident. There were no reported injuries to the four-person crew or to the 60 passengers.

Weather at the departure airport, approximately 19 minutes prior to departure, was reported as heavy rain showers and mist, and a temperature of 46 degrees (F). Upon arrival, at MKE, MWEA maintenance personnel inspected the aircraft and found ice accretions in the elevator control bay of the vertical stabilizer. Debris was also found covering the drainage holes within this bay. No other anomalies were detected with respect to the incident aircraft. No ice was found in any area that would have prevented movement of the elevator.

On April 9, 1999, approximately 0745 cst, the same airplane, N600ME, experienced a similar occurrence while in cruise flight. The aircraft had departed MKE en route to EWR. The weather, at MKE, at the departure time, was reported as rain showers and mist, and a temperature of 39 degrees (F). After leveling off at 29,000 feet altitude, the pilots determined that the elevator control would not respond to control inputs. The captain stated, in a written report, that he "applied more and more elevator backpressure until I [he] finally felt [the] elevator control 'bump' free and control was restored." The flight continued to EWR with no further difficulties.

After the April 9, 1999 occurrence, MWEA maintenance personnel inspected the aircraft and no anomalies were noted with respect to the elevator control difficulties.