Brazil’s ANAC has ordered and 175 operators to make modifications that will prevent hot engine exhaust air from leaking from engine precooler systems and damaging nearby wiring and related components.
The directive (ANAC AD 2013-11-01) gives operators 8,000 flight cycles or 12,000 hr. from its Nov. 4 effective date to install deflectors on left and right precooler exhaust flanges and apply silicone sealant to the precoolers. Operators also must verify that surrounding Electrical Wiring Interconnection System components are not damaged.
The directive was triggered by reports of bleed air leaks and related cockpit warnings. “Further investigation has shown that a leakage on the flange of the precooler refrigerating air exhaust duct caused the damaged and triggered the message[s],” the ANAC says.
Worst-case, the issue can cause engines to roll back to idle, the regulator adds.
ANAC suggests that operators stagger the work so both precoolers on the same aircraft are not serviced at the same time.
The Brazilian regulator based its directive onservice instructions sent out in August 2011. The and Australia’s Civil Aviation Safety Authority have adopted the ANAC directive as written.
The Aviation Week Intelligence Network Fleets database shows 346 E-170s and -175s in service, with about half of them flying for U.S. carriers.