What happened
On October 9, 2014, an Embraer EMB-505, registration PP-EMO, departed Brasília International Airport (SBBR) bound for Fortaleza (SBFZ) for a private transport flight. The aircraft was carrying two pilots and two passengers. During the initial climb, the crew observed the "FUEL IMP BYP" warning lights illuminating, indicating an issue with the engine fuel lines. Following standard checklists, the pilots performed a return to Brasília and landed the aircraft safely.
The investigation
CENIPA investigators examined the aircraft's fuel system and discovered that the fuel filters in both engines were clogged. Visual inspections of the fuel tanks and inspection windows revealed a white, crystalline residue that resembled ice after the kerosene had evaporated. Laboratory analysis at DCTA and CENPES confirmed that the residue was a nitrogen-based material consistent with urea.
Further investigation traced the contamination to the refueling process at the Brasília airport's aviation fuel reseller. Investigators found that the anti-icing additive (ULTRASOLVE AC HF) stored in the refueling truck (CTA 1477) had been contaminated with ARLA 32, an automotive urea-based liquid used in diesel engines to reduce nitrogen oxide emissions.
Security footage and interviews revealed that during a replenishment of the additive reservoir, a mechanic was interrupted by another task and left the task to an unqualified airport service assistant. This assistant, unaware that ARLA 32 was being handled, mistakenly placed a leftover 3-liter container of ARLA 32 into the additive storage depot, believing it to be the correct anti-icing additive. The refueling operator later used this contaminated container to top up the truck's additive reservoir.
Findings
- The primary cause of the fuel system blockage was the contamination of the anti-icing additive with ARLA 32.
- High workload and the practice of informal task delegation among ground staff led to the error.
- Lack of specific procedures and designated areas for handling new products like ARLA 32 in the airport environment.
- Inadequate human and material resources to ensure tasks were completed without interruption.
- The additive is added to the fuel after the filtration process, meaning there was no mechanical barrier to prevent the contaminated additive from reaching the aircraft engines.