What happened
On 15 February 2002, an Embraer EMB-145EP, registration G-RJXC, was conducting a scheduled passenger flight from Leeds Bradford International Airport to Paris Charles De Gaulle. While cruising at flight level 250, the crew received a warning indicating the main door was open, followed shortly by an advisory message showing low quantity in the No 2 hydraulic system.
As the crew diverted to East Midlands Airport, the hydraulic fluid level continued to drop. During the approach, the commander selected the speedbrakes to open to expedite the descent. While the EICAS indicated the speedbrakes had closed, the loss of hydraulic pressure prevented the actuators from fully locking. This caused the right outboard spoiler to deploy uncommanded, followed by the left outboard spoiler.
As the aircraft progressed to a landing flap 45° configuration, the left spoiler opened again. This triggered a significant lateral imbalance, forcing the commander to apply substantial right aileron and right control trim to maintain wings level. The aircraft landed safely, though the crew subsequently requested fire service assistance due to a brake overheat caution during the landing roll.
The investigation
The AAIB investigation focused on the cause of the hydraulic leak and the subsequent flight control behavior. Investigators found that the No 2 system leak originated from a loose connection on the engine-driven pump case tube drain union, likely caused by in-service vibrations.
Testing on a similar aircraft confirmed that if hydraulic pressure is lost before the speedbrake actuators are mechanically locked, the panels can remain in a "floating" state. The investigation also examined the discrepancy between the aircraft's various manuals, noting that the crew had not been specifically trained on the risks of asymmetric spoiler deployment during recent type conversion.