This article is published in Aviation Daily part of Aviation Week Intelligence Network (AWIN), and is complimentary through Feb 05, 2025. For information on becoming an AWIN Member to access more content like this, click here.
An airworthiness directive for ATR turboprops has come into force that requires more regular inspections of the pressure regulator and shut-off valves (PRSOV) that regulate the engine bleed air used for airframe and engine de-icing.
The European Union Aviation Safety Agency (EASA) gave the instruction after a design review with ATR identified the need to reduce the current interval of the functional test of each PRSOV and extend its scope. The change, which became effective on Jan. 24, is intended to reduce the risk of losing anti-icing protection for the engines’ air intakes.
Functional checks are now required at intervals ranging from 650 flight hr. to 1,050 flight hr., depending on the model of ATR. All ATRs are required to have their first check within the next six months.
The airframer told Aviation Week that it has developed a pro-active maintenance procedure that provides instructions for the functional testing of the affected components, which was distributed to all ATR operators through a dedicated communication. “It is important to note that, to date, ATR has had no in-service events related to this failure condition,” ATR said.
De-icing of ATRs has come under scrutiny following the fatal accident of a Voepass Linhas Aéreas ATR 72-500 in August 2024. A preliminary report filed a month after the Flight 2283 crash said investigators would be looking to see whether a de-icing system malfunctioned and how the flight crew reacted in response to the issue and increasingly dangerous icing conditions. The final accident report has not been issued yet.
According to ATR, airframe de-icing of the wings and horizontal stabilizer leading edges is activated when ice accretion is observed by the flight crew, while engine de-icing is activated when the aircraft flies in visible moisture. Wing, empennage and engine de-icing are ensured by pneumatic de-icers consisting of dual chambers boots, inflated alternately by air bled from the high-pressure compressors of engines 1 and 2. The PRSOV is vital to regulating the pressure of the bleed air to maintain consistent functionality.
Related Content
