History of the flight
On 6 February 2007, an Airbus A319-111 (registration G-EZIU) operated a scheduled passenger flight from Barcelona to Liverpool. The co-pilot was the pilot flying. While crossing the south coast of England, an Electronic Centralised Aircraft Monitor (ECAM) caution message indicating 'ENG 2 EGT' appeared with an aural tone. The co-pilot continued flying on autopilot while the commander reviewed the ECAM checklist. Subsequently, an 'ENG 2 EGT OVER LIMIT' caution appeared, requiring the No 2 engine thrust lever to be moved to idle and the engine shut down. As the commander retarded the thrust lever, an 'ENG 1 EGT OVER LIMIT' caution appeared with identical actions. Observing normal engine parameter indications, the commander deemed the cautions probably spurious and reinstated the No 2 thrust lever.
During this period, the captain's Primary Flight Display (PFD) and Navigation Display (ND) showed red indications similar to inertial reference system alignment, along with intermittent 'USE MAN PITCH TRIM' and 'MAN PITCH TRIM ONLY' messages, even though flight control degradation had not occurred. The co-pilot's PFD showed intermittent 'CHECK ATT' messages. Other anomalies included loss of gross weight, outside air temperature and clock displays.
The commander declared a MAYDAY and requested diversion to London Stansted due to its favourable weather and long runway. ATC initially assigned Runway 23, but later changed to Runway 05, requiring the commander to reprogram the Flight Management System. ECAM cautions and aural tones continued frequently. The commander briefed the cabin crew and informed passengers. The co-pilot armed approach mode and engaged the second autopilot. The commander, anticipating an overshoot, took manual control for a visual approach. On selecting landing gear down, one ECAM landing gear indication showed unsafe, though the independent green 'gear down and locked' lights were all illuminated. At approximately 700 ft, the No 1 engine N1 indication turned amber and indicated slow rotation. The landing, attended by Aerodrome Fire and Rescue Service, was uneventful.
The crew noted that no guidance existed in available manuals for the combination of symptoms experienced.
Aircraft information
The Airbus A319 is equipped with an Electronic Instrument System (EIS) including three identical Display Management Computers (DMCs). During normal operations, DMC 1 supplies the captain's displays, DMC 2 supplies the co-pilot's, and DMC 3 is standby. The DMCs generate engine exceedence thresholds and transmit them to Flight Warning Computers (FWCs), which generate caution messages for parameter discrepancies. The DMCs contain circuit boards with PUMA 0 and PUMA 1 components; engine parameter data is processed in parallel. If a DMC fails, messages are still displayed due to redundancy.
Recorded information
The aircraft was fitted with a solid-state Cockpit Voice Recorder (CVR) and Flight Data Recorder (FDR). FDR data showed the aircraft north of the Isle of Wight at FL380, 246 kt, with autopilot and autothrottle engaged. At 11:46:43 hrs, the first Master Caution chime was recorded. The No 2 thrust lever was retarded about 28 seconds later. After 26 seconds, the No 2 lever began advancing over 38 seconds. In the first three minutes, 61 Master Caution chimes were recorded; approximately 460 chimes occurred in the 33 minutes between first and last. No DMC fault was recorded on the FDR.
Aircraft examination
Maintenance troubleshooting data confirmed numerous recurrent ECAM caution messages. The 'Post Flight Report' included discrepancy messages for ENG 2 N1, ENG 2 N2, ENG 2 EGT, NAV ATT, ENG 1 FF and ENG 2 FF. Engine trend monitoring showed no developing problems. Engine ECU data showed no faults or limit exceedances. Ground runs with the EIS DMC switch in all positions were performed to check correct DMC operation.