Operators of ATR turboprops are being instructed to conduct urgent checks for possible wrongly-assembled valves on the engine fire-extinguishing systems.

The European Union Aviation Safety Agency has ordered the checks in an emergency directive which covers both the ATR 42 and 72, up to the -500 variants.

EASA states that a scheduled maintenance operation identified incorrect marking and assembly of two-way valves in the left- and right-hand fire-extinguishing systems.

As a result, says the regulator, the systems “did not operate as intended”.

Similarly-affected systems could suffer from “reduced performance” in the event of an engine fire, it adds.

ATR engine-c-Arpingstone Creative Commons

Source: Arpingstone/Creative Commons

ATR operators must check two-way valves in the extinguishing system

ATR has issued inspection and rework instructions for the parts involved.

EASA is requiring operators to carry out a functional check of these parts, within 21 days, and undertake corrective measures if necessary – including replacing affected components before the next flight.

Older-variant ATRs are powered by Pratt & Whitney Canada PW124 or PW127 engines.