Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation.
On 22 February 2020 at 0900 Eastern Daylight-saving Time, a twin-engine Cessna 404 with three crew commenced its take‑off run on runway 17 at Essendon Airport, Victoria. During rotation the right engine fire extinguisher discharged without crew command. The crew reported hearing a loud ‘whoosh’ sound and an alert light in the cockpit illuminated indicating zero pressure in the right engine fire extinguisher. The crew continued the take-off and observed normal engine indications during the climb to 5,000 ft.
The crew discussed their situation and elected to conduct a return to Essendon Airport. To avoid an overweight landing, they decided to enter a holding pattern to burn off sufficient fuel. The crew contacted air traffic control (ATC) advising them of their decision and were directed to hold at a nearby waypoint.
About 20 minutes into the holding pattern, the crew detected a burning odour in the cockpit but no smoke was evident. The crew advised ATC of the smell and requested to cancel the holding pattern and land at Essendon Airport. ATC initiated an uncertainty phase (INCERFA) and cleared the aircraft for a straight-in approach to runway 26. The crew pulled the fire detection and extinguishing system circuit breakers, and the odour disappeared temporarily before returning during final approach. Shortly afterwards, a safe landing was completed after which ATC cancelled the INCERFA.
Engineers inspected the aircraft after landing and found that the fire extinguisher discharge button in the cockpit was faulty but the source of the odour could not be determined. After replacing the button and the discharged fire extinguisher, the aircraft returned to service.
The unintended discharge of the engine fire extinguisher occurred during a critical phase of flight and was not covered by an emergency response procedure. However, the crew’s actions and decisions ensured that aircraft safety was maintained at all times.
Prompt decision making between crewmembers and communication with ATC is critical for timely and effective management of a potential in-flight emergency.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.
- Rotation: the positive, nose-up, movement of an aircraft about the lateral (pitch) axis immediately before becoming airborne.
- When the engine fire extinguishers are operating normally, only the crew can discharge them via a button in the cockpit.
- Uncertainty phase (INCERFA): an emergency phase declared by the air traffic services (ATS) when uncertainty exists as to the safety of an aircraft and its occupants.
|Date:||22 February 2020||Investigation status:||Completed|
|Release Date:||24 March 2020||Occurrence category:||Incident|
|Report status:||Final||Highest injury level:||None|
|Aircraft manufacturer||Cessna Aircraft Company|
|Type of operation||Aerial Work|
|Damage to aircraft||Nil|
|Departure point||Essendon Airport, Victoria|