An AVRO 146-RJ100, G-CFAE, was being readied at Edinburgh Airport, Scotland after a night stop for a 08.00 hrs departure to London Ciry Airport, England. With the aircraft still parked at Stand 22 the crew were going through their flight preparation procedure. Part of that was the check of the aircraft technical status, 2 items were on the aircraft Hold Item List (The Hold Item List is a list of current allowable defective aircraft equipment in accordance with relevant Airworthiness Data);
APU (Auxiliary Power Unit) unserviceable The APU provides electrical power and bleed air for numerous aircraft systems
Minor issue with a passenger seat row The purser was briefed by the Captain about this defect
The AVRO RJ family, the RJ100 is the second from the back (Source: www.pilotweb.aero)
With the APU unserviceable an external power unit provided the aircraft with the 115 V 400Hz electrical power to energise the aircraft systems and start the engines. After receiving their start-up clearance the crew established contact ground staff to get the all clear to start Engine #4 (Right-Hand outboard engine) using the external power. The #4 engine was started without any problem and once the engine was stabilised the generator on the engine was switched on, and the ground staff were told to disconnect the external power unit. With the External Power Unit disconnected the aircraft was pushed back onto the taxi track with the aircraft pointing in a westerly direction. After the pushback equipment was disconnected and clear of the aircraft the ground crew informed the crew that they were cleared to start the other three engines in sequence from right to left (Engine #3, #2 and #1 last). The crew commenced the start of the #3 engine (right-hand inboard engine) and just after initiating the start, the crew realised they did not increase the thrust setting on the #4 engine to provide enough energy to put the heavy load of an engine start on the generator. With the electrical starter engaged on the #3 engine the load on the #4 generator was so high that the #4 engine speed dropped, which caused the engine electronic controller to increase the fuel flow to the engine. However, the amount of fuel was too much for an engine at such a low speed. The fuel ignited and caused flames to exit the engine exhaust.
Example of a tail pipe fire (due to another reason then on the incident discussed in this blog, Click on the picture to see the video of this tailpipe fire. (source youtube.com)
This was correctly identified by the ground crew who immediately informed the flight crew of this situation. The fuel selector for the #4 engine was set to ‘OFF’ when the Captain reached for the fire handle the co-pilot already had his hand on the fire handle, and on the captain’s instruction, the co-pilot pulled the fire handle and discharged both fire extinguishers into the #4 engine. With all engines off, the aircraft electrical system was now powered by the aircraft battery, the captain transmitted a MAYDAY call to ATC, which was confirmed immediately by ATC, alerting the Airport Fire and Rescue Service. The flight crew noticed the ‘DOOR’ open warming light illuminate indicating that one of the cabin doors was open, they also heard the cabin crew tell the passengers “get out”, an evacuation of the passengers had been started by the cabin crew. The commander unlocked to cockpit door and shortly after that, the purser came into the flight deck to inform the flight crew that all passengers were off the aircraft.
A member of the cabin crew was informed by passengers that there was a 6 feet (1.8 meters) flame from an engine, he rushed forward informing the purser, who initiated the evacuation. After completing the relevant checklist the flight crew were the last ones leaving the aircraft after confirming the aircraft was empty. Right at that time, the Airport Fire and Rescue Service arrived.
The incident was investigated by the Air Accident Investigation Branch, there full report is available by clicking here.
Flight Data Recorder data from the incident (Source aaib.gov.uk)
After the incident the airlines maintenance department carried out a detailed inspection of the engine and related systems without finding any mechanical fault, nor did the engine Full Authority Digital Engine Control memory contain any fault codes.
After replacement of the engine fire extinguishers engine test runs were carried out without any further fault, subsequently the aircraft was returned to service.