Event Details


Title:Frozen elevator control, Douglas DC-9-32, April 9, 1999
Micro summary:This Douglas DC-9-32's elevator was frozen in cruise.
Event Time:1999-04-09 at 930 CDT
File Name:1999-04-09-US.pdf
Publishing Agency:National Transportation Safety Board (NTSB)
Publishing Country:USA
Report number:CHI99IA136
Pages:5
Site of event:Dubuque, IA
Departure:General Mitchell International Airport, Milwaukee, Wisconsin, USA
Destination:Eppley Field, Omaha, Nebraska, USA
Airplane Type(s):Douglas DC-9-32
Flight Phase:Cruise
Registration(s):N205ME
Operator(s):Midwest Express Airlines
Type of flight:Revenue
Occupants:91
Fatalities:0
Serious Injuries:0
Minor/Non-Injured:91
Other Injuries:0
Executive Summary:

NTSB short summary:

the frozen elevator control. Factors to the incident were the rain and the low temperature.

NTSB synopsis:

The airplane departed in rain with a surface temperature of 39 degrees Fahrenheit. Upon reaching cruise altitude, the flight crew discovered that the elevator control '...was found to be frozen and would not move.' The pilot said that the aircraft was flown using primary and alternate trim until a descent was made to 'warmer air', and the '... elevator thawed out...' and normal control was regained. An inspection of the aircraft after the incident failed to reveal any anomalies with respect or the aircraft or aircraft systems. On two other occasions, Midwest Express Airlines (MWEA) DC9 aircraft have experienced elevator control difficulties. On these occurrences, the aircraft departed in rain with temperatures of 46 degrees Fahrenheit and 39 degrees Fahrenheit respectively. On one of the occurrences, MWEA maintenance personnel found ice accretions in the elevator control bay of the vertical stabilizer.

NTSB factual narrative text:

On April 9, 1999, approximately 0930 central daylight time, a McDonnel Douglas DC9-32, N205ME, operated by Midwest Express Airlines, Inc. (MWEA), experienced a loss of elevator control while in cruise flight near Dubuque, Iowa. The 14 CFR Part 121 flight departed General Mitchell International Airport, Milwaukee, Wisconsin, at 0920, enroute to Eppley Airfield, Omaha, Nebraska. The flight crew piloted the aircraft using the elevator trim system until regaining elevator control after descent. The airplane landed at Eppley Airfield without further incident. There were no reported injuries to the 6 crew members or to the 85 passengers.

The pilot stated that the aircraft departed General Mitchell International Airport in "moderate wind driven rain." The pilot said that when the aircraft was leveled off, after climb, the elevator control "...was found to be frozen and would not move." The pilot further stated that when a descent was made to "warmer air", the "... elevator thawed out..." and normal control was regained.

A weather report for General Mitchell International Airport, MKE, at 0856, showed a temperature of 39 degrees Fahrenheit, rain, mist, and winds from 030 degrees magnetic at 20 knots gusting to 28 knots.

An inspection of the aircraft after the incident failed to reveal any anomalies with respect or the aircraft or aircraft systems.

On two other occasions, MWEA DC9 aircraft experienced elevator control difficulties. On these occurrences, the aircraft departed in rain with temperatures of 46 degrees Fahrenheit and 39 degrees Fahrenheit respectively. On one of the occurrences, MWEA maintenance personnel found ice accretions in the elevator control bay of the vertical stabilizer (Reference: CHI99IA115).
Learning Keywords:Operations - Icing
Systems - Elevator, Stabilizer, Rudder, Ailerons
Systems - Flight Control System
Close match:Pitch control problems, Boeing 767-300, March 27, 2001
Loss of elevator control, Douglas DC-9-14, March 21, 1999
Frozen aileron cable, Boeing 767-222, June 7, 2000
Frozen elevators, McDonnell Douglas MD-82, February 5, 1999
Flight control system problems following icing, Avro 146-RJ100 and others, G-JEAV, January 17, 2006
Flight control difficulties, McDonnell Douglas MD-11-C, I-DUPA, January 14, 2003

 




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