Russian regulator urges de-icing caution after detailing more 737 engine-surge occurrences

Russian authorities have discovered that at least one other Boeing 737 operator has encountered engine instability arising from blade contamination during winter operations. Federal air transport regulator Rosaviatsia states that a 737-800 of Smartavia was involved in an occurrence on 16 January while undergoing maintenance. It says the aircraft (RA-73654) experienced alternate surges in both CFM International CFM56 engines during tests. Inspection found a “white coating” on the low- and high-pressure compressors. The problem was resolved with engine wash procedures. Rosaviatsia had previously indicated issues with CFM56 engines on 737s operated by S7 Airlines, and it has disclosed details of four incidents, all involving S7 737-800s. After take-off from Novosibirsk on 8 December last year, the crew of an aircraft registered RA-73665 reported surges in both engines, and opted to return to the airport. Rosaviatsia says the probable cause was unstable operation of the high-pressure compressors in each powerplant, owing to contamination of the compressors’ blades from “intensive” use of de-icing fluid while the engines were running. The regulator also refers to ingestion of salts from the runway during taxiing. Under certain conditions, it says, this can lead to disruption of the airflow through the compressor blades.<br/>