Frozen Elevator Nearly Downs Jet

According to a newly released Air Accident Investigation Board of Norway (AIBN) final report, de-icing fluid entered a Norwegian Air Shuttle Boeing 737-800's tail section and froze on three of four input cranks to the two elevator power control units (PCU), causing a Dec. 26, 2012 unintentional pitch up incident that nearly resulted in a complete loss of control while the aircraft was on approach to Kittila Airport in Finland. The Boeing was deiced before departure at Helsinki Airport to remove about 10 inches of snow that had accumulated while the aircraft sat outside for three days.

The flight appeared normal until the aircraft was established on the Kittila localizer in a flaps five configuration with all automation engaged. As the aircraft intercepted the glideslope, the nose of the Boeing began to pitch up and the aircraft began to climb. The two pilots responded with forward pressure on the control column, but they made no attempt to disconnect the autopilot. The nose eventually reached a 38.5-degree deck angle and a 25-degree angle of attack as the airspeed dropped to 118 knots before control was slowly regained despite almost no elevator control. The autopilot disconnected itself and the crew conducted a second approach to a safe landing.