What happened
On 20 March 2001, a DHC-8-3 and registration G-JEDD was operating at Bristol International Airport. While taxiing in icing conditions, the aircraft experienced engine flameouts. Although the commander had intended to use manual ignition for the takeoff, the necessary checks during the Line Up phase were not completed before the engines failed.
The investigation
The AAIB investigation focused on the engine ignition settings and the aircraft's ice protection procedures. It was established that the operator's existing checklist at the time only required ice protection and ignition to be selected 'as required' during Line Up checks. Furthermore, the aircraft, G-JEDD, lacked a specific modification known as the Auto Relight System (Service Bulletin 8-74-02), which automatically activates igniters if engine power drops below a certain threshold.
Investigators found that the aircraft's engine intakes were likely affected by ice breakaway, causing a temporary interruption in airflow. Because the ignition had not been manually set to the 'ON' position, the engines were unable to recover from the transient power loss.
Findings
- The primary cause of the engine flameouts was the failure to select the engine ignition to the manual 'ON' position during taxi in icing conditions.
- The aircraft's specific configuration did not include the Auto Relight System modification, which would have provided automatic protection against such flameouts.
- The operator's checklist at the time of the incident did not explicitly mandate an ice protection check prior to taxi, though this was subsequently revised following the event.
Safety action
- The operator updated its aircraft checklist to include a specific check for ice protection before taxiing.
- Following the incident, all Dash 8 operators within the United Kingdom chose to implement the Service Bulletin 8-74-02 modification to enhance engine protection.
- The manufacturer committed to revising service letters to emphasize the necessity of ensuring engine intakes are free from frozen contaminants before departure.