The Swedish Accident Investigation Board SHK issued a preliminary statement on an incident that occurred in January 2010 involving a BAe ATP, citing thickened de-icing fluid as a possible factor.
A BAe ATP cargo plane registered SE-MAP was involved in a takeoff incident at Helsinki/Vantaa Airport (HEL). The airplane was loaded with cargo and the centre of gravity was within the permitted limits.
No outstanding technical defects or faults concerning the aircraft had been noted. There were no other difficulties or problem areas – traffic or operational – to affect the implementation of the flight.
Due to the weather conditions at the time the commander ordered that the aircraft should be de-iced before take-off. Taking into account the fact that it was snowing, it was decided to perform two-stage de-icing, which meant that both type I (removal of ice, frost and snow) and type II (prevention of ice forming again) would be carried out on the aircraft.
After de-icing had been completed, SE-MAP requested permission to taxi out, and clearance was received to taxi to the holding point runway 22R for take-off. During taxiing out, the pre-take-off checklist was completed, which among other things included checks that the control surfaces had full and free movement. The co-pilot was the PF (Pilot Flying) for this particular flight.
When the aircraft had reached the calculated rotation speed (Vr), the PF pulled back the control column in order to rotate the aircraft but without any result. According to witness statements the control column was as far back as it could be, with no sign that the aircraft would leave the ground. The commander then aborted the take-off and the aircraft taxied in to the terminal again.
After parking, the load and its distribution were checked, but nothing abnormal was found. No other faults in the aircraft were found. The commander then cancelled the flight.
Investigators identified several previous occurrences with common factors. Given the fact that thickened anti-icing fluids might interfere with normal control of the elevators, several measures were taken. Following a measurement of elevator clearances on all ATP aircraft BAe Systems announced that certain individual aircraft were “NOT approved for continued operation”, after the application of Type I or Type II/IV fluids.
Then, in December2010 EASA published an AD (Airworthiness Directive 2010-0263), containing restrictions on ATP operations. Principally the Directive contained the above-mentioned rules from the type certificate holder. An exception was however made for de-icing with (un-thickened) Type I fluids.
The investigation is continuing.