What happened
On 1 August 2008, an Embraer ERJ 190-200 LR (Embraer 195), registration G-FBEH, was operating a scheduled passenger flight from Manchester to Belfast City. During the climb to 24,000 feet, the flight crew detected a sulphurous smell, similar to a struck match, within the cockpit. As the aircraft continued its ascent, the smell intensified and a haze became visible in the cabin.
Fearing a fire, the commander declared a MAYDAY and diverted the aircraft to Ronaldsway Airport on the Isle of Man. During the descent, the pilots donned oxygen masks to protect themselves from the fumes. However, technical issues with the masks made communication between the pilots, the cabin crew, and Air Traffic Control extremely difficult, forcing the crew to shout to be heard.
Upon landing, the commander ordered an immediate evacuation. While the left overwing exit functioned correctly, the right overwing emergency exit became jammed. Passengers evacuating via the left wing reported confusion regarding the correct path to the ground, as the markings on the wing were not clearly understood. During the evacuation, several passengers experienced minor injuries due to the steepness of the slides and the speed of their descent. /n## The investigation
Investigators examined the aircraft's flight recorders and the physical components of the air conditioning system. They found that the No 1 Air Cycle Machine (ACM) had suffered a failure where the turbine blades had fractured due to fatigue. This failure released hot metallic particles into the cabin air system, creating the smoke and fumes.
Regarding the evacuation, the investigation found that the right overwing exit door had jammed because the door trim was caught under the ceiling edge panel. This was caused by insufficient clearance between these components. Furthermore, the investigation looked into the communication difficulties and found that the captain's oxygen mask microphone was malfunctioning due to a manufacturing defect in the internal cut-out mechanism.
Findings
- The primary cause of the smoke and fumes was the failure of the No 1 Air Cycle Machine turbine blades due to fatigue cracking related to a known resonance condition.
- The right overwing exit failed to open because the clearance between the door trim and the ceiling panel was insufficient to prevent jamming during an energetic opening.
- Communication between the flight crew and others was severely hindered by technical malfunctions in the oxygen mask microphone system.
- The effectiveness of the evacuation was impacted by ambiguous markings on the wing surface, which led some passengers to be unsure of the correct route to the ground.
Safety action
- Safety Recommendation 2010-007: It is recommended that the EASA review the design and visibility of wing surface markings on public transport aircraft to ensure escape routes are unambiguous.
- Safety Recommendation 2010-008: It is recommended that Embraer modify the overwing exits on Embraer 195 aircraft to prevent the door trim from interfering with the ceiling edge panel.