| 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. |
What happened
On 20 September 2019, a Pilatus Britten-Norman BN2A-21 Islander operated a return charter flight from Horn Island to York Island, Queensland. There was one pilot and four passengers on board.
During taxi after landing at York Island in the morning, the pilot turned the fuel pumps on and switched the tank selector from main tanks to tip tanks. After the passengers disembarked and the aircraft was parked on the apron, the pilot completed his flight log and dipped the fuel tanks, confirming his estimate of remaining fuel on board.
The passengers returned late afternoon and the aircraft departed for its return flight to Horn Island at about 1600 Eastern Standard Time.
During cruise, the pilot observed the no. 1 engine surging. He immediately turned on both fuel pumps and monitored all instruments. He noticed that the fuel gauges were indicating that the tip tanks were almost empty and the main tanks had gained a significant amount of fuel. The pilot switched from tip tanks to main tanks and the surging stopped. As a precaution, he conducted a diversion to Warraber Island.
After landing, the pilot checked the fuel in the tip tanks and discovered that the tanks were empty and the fuel had transferred into the main tanks.
Engineering inspection
Following the incident, engineers determined that after switching the fuel selector from the main tanks to the tip tanks, the aircraft was shut down without allowing adequate time for the fuel transfer lines to close. This resulted in the fuel from the tip tanks to drain into the main tanks.
Safety action
As a result of this occurrence, the aircraft operator has advised the ATSB that they are taking the following safety actions:
- An internal company document was raised to review procedures by dipping the fuel tanks before take-off when on the ground for 30 minutes or more.
- A safety meeting was held to raise awareness and discuss the importance of fuel procedures, including allowing 5 to 10 minutes before shut down when switching to tip tanks on the ground.
- A note has been included in the aircraft close to where the switches are, advising the importance of allowing time for the fuel selection change.
Safety message
Keeping fuel supplied to the engines during flight relies on the pilot’s knowledge of the aircraft’s fuel supply system and being familiar and proficient in its use. Accidents and incidents involving fuel mismanagement are an ongoing aviation safety concern, particularly those involving complex fuel delivery systems. The ATSB publication, Avoidable Accidents No. 5 - Starved and exhausted: Fuel management aviation accidents (AR-2011-112), is available from the ATSB website.
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.