What happened
On January 12, 2004, a Cessna 550 Citation II, registered PH-DYN, was taxiing at Rotterdam Airport for a commercial flight to Strasbourg. The aircraft, carrying two crew members and six passengers, was moving along the F-apron following recent rain. While attempting a left-hand turn using nosewheel steering and the left-hand wheel brake, the pilot found that applying maximum pressure to the brake pedal resulted in minimal deceleration. Despite the co-pilot attempting to assist with braking, the aircraft failed to complete the turn within the required radius. Consequently, the right wing struck a hangar door post, causing the aircraft to veer and run through a hangar door. The impact resulted in 3 passengers with neck complaints and severe damage to the aircraft.
The investigation
The investigation focused on the functionality of the braking and antiskid systems. Sixteen components of the brake and antiskid system were sent to the United States for inspection by manufacturers under the supervision of the NTSB and FAA. Testing revealed that the nosewheel steering, brakes, and hydraulic fluid levels were all functioning normally. Furthermore, the emergency brake system was found to be in working order, though investigators determined it was not utilized during the incident.
Investigators also examined the operator's taxi procedures. The airline's checklist required a brake test as the first item upon movement, but the crew could not confirm if this had been performed. The investigation noted that the operator's practice of delaying certain checklist items until reaching a specific marker was intended to reduce inattention, but it may have delayed the detection of a braking issue.
Findings
Several factors contributed to the collision. The investigation considered that the damp surface of the apron, combined with reduced weight on the left-hand wheel during the turn, might have caused the wheel to lock. If the antiskid system was active, a momentary loss of signal from the speed transducer could have caused the electronic control box to reduce brake pressure, leading to the wide turn.
The failure to perform an immediate brake test upon movement was identified as a critical factor, as an earlier test might have revealed the lack of braking effectiveness at a much lower speed, allowing more time to deploy the emergency brake.