The FAA has issued a special airworthiness Information bulletin (SAIB) regarding last month’s incident where five aircraft were serviced with jet fuel contaminated with diesel exhaust fluid (DEF) at Miami Opa-Locka Executive Airport, while an additional nine aircraft were fueled using equipment that had been exposed to DEF. The agency identified the aircraft, including the Falcon 900EX that was forced to make an emergency return to base as its engines began failing due to clogged fuel systems, and noted that it has sent a copy of the SAIB to the registered owner of each.
While the agency said the issue does not currently warrant issuance of a broader Airworthiness Directive, it is requesting that owners and operators of the aircraft involved report any service difficulties or anomalies. Further, it recommends they consult with the OEMs of the aircraft, engines, and APUs to determine the appropriate inspection and corrective maintenance actions required.
When mixed with jet fuel, DEF will react and form crystalline deposits that can accumulate on filters and other fuel system components such as fuel nozzles. The deposits can also settle in the fuel tanks, where they might potentially later become dislodged and cause problems. "The crystalline deposits are not soluble in fuel, so they cannot be removed by flushing the airplane fuel system with jet fuel," the FAA added.