Fokker is investigating in-service reports of Fokker 100 fuel boost pump wiring damage and is considering improper maintenance as the cause.

The issue, detailed in an Australian Civil Aviation Safety Authority (CASA) airworthiness bulletin, focuses on burnt wiring insulation. In one case, the damage was discovered during a pump repair, CASA explains. 

“The wiring harness for the [left] rear fuel boost pump canister was removed for access to allow defect rectification of a fuel leak,” CASA says. “The wiring harness had fuel present within the harness conduit and the rubber insulation on the plug was found severely damaged.”

Further investigation revealed the likely cause as an incorrectly installed “backshell” at the end of the harness. 

Damage to the harness assembly has been reported before, CASA notes. Fokker says that so long as the associated pump remains submerged in fuel, “there is no immediate safety risk,” the authority adds.

As a precaution, Fokker in late October issued a maintenance manual change, telling operators to pull and tag boost pump circuit breakers during maintenance activities if collector tanks have 200 liters or less of fuel in them. This protects against the dry-running of pumps. The manufacturer also recommends shutting off center wing tank transfer pumps as soon as the center tank is empty.

CASA’s bulletin echoes Fokker’s recommendations and suggests that operators check fuel canister connector backshells “for correct installation.”

Meanwhile, Fokker is further investigating the in-service reports to pinpoint the exact cause of the damage. The manufacturer is exploring whether fuel boost pump replacements—specifically improper wiring harness connections—are the root cause. 

Depending on its findings, the manufacturer may follow up with a service letter, CASA says. The fuel pump wiring damage issues are isolated to Fokker 100s, according to the manufacturer.

There are about 160 Fokker 100s still in service, according to the Aviation Week Intelligence Network Fleets database. Australia, with 38, is the county with the largest fleet.