In September of 2016, the ATSB received a report from a helicopter operator in Cloncurry, Queensland, that while inspecting one of several recently arrived drums, a pilot had discovered white particles floating in the Jet A1 fuel. The same material, described as small pieces of white debris that tended to settle at the base of the drum, was subsequently found in all seven of the drums that were opened and inspected.
The same operator would subsequently report further instances of fuel drum contaminants, from a second location in Queensland and two remote sites in Western Australia on separate occasions in 2016, 2017 and 2019.
The operator advised that the contaminated drums had been filled by different refuelling companies but all had been manufactured the same company, VIP Packaging. Batch numbers and manufacturing dates on the drums across the incidents did not show any correlation.
There are a number of ways to minimize the likelihood of using contaminated fuel.
The ATSB determined that the contaminant was a sealant used by the drum manufacturer on the lid and base of the drums. The sealant’s mechanical properties were found to degrade when exposed to Jet A1 fuel. This, in combination with vibration and drum deformation during transport to remote locations over rough roads, likely resulted in pieces of sealant entering the fuel within the drum.
“Fuel sourced from drum stock is particularly susceptible to contamination. However, there are a number of ways to minimise the likelihood of using contaminated fuel,” ATSB Director Transport Safety Stuart Macleod said.
“These include applying appropriate drum handling and storage methods; visually inspecting drums for contaminants prior to refuelling activities; regularly inspecting fuel pump filters; and conducting fuel drains from the aircraft after each refuel for visual inspection.”
Mr Macleod noted that the investigation established that no contaminants were found in any aircraft exposed to the fuel.
“Filtration during the refuelling process appears to be effective in preventing these contaminants from reaching the aircraft and there was no evidence that the sealant dissolved in the fuel.”
The report notes it is possible that the sealant may break down into small enough pieces to pass through a fuel transfer pump’s micronic pre-filter and reach the aircraft’s fuel tank, and from there pass through the aircraft’s fuel filtration system and enter the engine.
“However, if that was to occur, the particles would be in minor quantities and too small to affect engine operation,” Mr Macleod said.
“As long as fuel is filtered as required under the regulations, and in accordance with best practice, harmful contaminants should not be able to reach the aircraft.”
For useful information on the use of drum stock, read investigation report AO-2016-144: Drum Stock Fuel Contamination