What happened
On 5 April 2022, a Saab 340B, registered VH-ZRK, was being prepared for a scheduled flight from Melbourne to King Island. During the engine start sequence, a ground crew member disconnected the ground power unit (GPU) without instruction, which interrupted the start process.
To address the interruption, the flight crew began the motoring procedure to clear residual fuel. During this process, a tailpipe fire developed in the left engine. A ground marshaller observed flames and smoke and used hand signals to alert the cockpit. Because the crew could not see the rear of the engine from the flight deck, and because the marshaller used non-standard signals, the crew initially attempted to continue the procedure.
Upon observing rising interstage turbine temperatures and receiving signals from the ground, the captain decided to shut down both engines and discharge the fire extinguishers. The captain then ordered an emergency evacuation. The evacuation was complicated by several factors: the flight attendant was initially unaware of the order, some passengers attempted to grab baggage, and the emergency exit row passengers did not utilize a usable exit. Two passengers sustained minor injuries during the process.
The investigation
The ATSB examined cockpit voice recordings, CCTV footage, and interviews with the crew and ground staff. The investigation focused on the communication breakdown between the ground and flight crews, the sequence of the engine start interruption, and the effectiveness of the evacuation procedures. The investigation also reviewed the operator's training protocols regarding hand signals and emergency communications.
Findings
- The primary cause of the tailpipe fire was the incomplete motoring cycles caused by non-standard hand signals from the ground crew regarding the observed smoke and flames.
- The captain's decision to evacuate was made without communicating the specific observations or the intended plan to the first officer.
- The evacuation order was not immediately recognized by the cabin crew because the captain used a secondary chime signal rather than a primary public address announcement.
- The evacuation was delayed because passengers in the exit row did not open a functional exit and some passengers attempted to retrieve cabin baggage.
- There was a lack of standardized, recurrent training for both flight and ground crews regarding the specific hand signals required for emergency communication.
Safety action
Following the incident, Regional Express implemented several corrective measures, including:
- Developing a new, specific hand signal to indicate an interrupted engine start.
- Updating training content for both ground and flight crews to include updated marshalling and dispatch procedures.
- Distributing hand signal posters in high-traffic crew areas to improve visual recognition and standardization.