The restrictions had prevented airlines from sourcing parts and repairs from Western providers.
Unlike routine maintenance work, the faults with the A320neo engines – which stem from the use of contaminated powdered metal in some parts – require specialist intervention from manufacturer Pratt & Whitney.
That means they must be removed after reaching a specified number of flights, with repairs taking up to 300 days per engine.
Airlines around the world have been affected – including European discount carrier Wizz Air, – but for most operators the groundings represent a temporary inconvenience.
However, for S7 and other Russian airlines, they are likely to represent a permanent loss of capacity, at least until the end of the war in Ukraine and a possible lifting of sanctions.
Russian media cited a transport ministry source as saying that neither S7’s engineering division nor Iran, which has years of experience keeping planes flying in the face of sanctions, has been able to carry out the required repairs.
S7 has already grounded 15 of its 31 A320neo jets – up from about half a dozen five months ago – and all eight of its larger A321neo aircraft, according to figures published on the CH-Aviation website. That would leave just 16 of the planes still operational.
The company also has older A320 models unaffected by the engine issue, as well as Boeing 737s, though it’s not clear how many of those remain serviceable.
S7 ranks second in size among Russian airlines after state-owned Aeroflot and is the country’s leading operator on domestic routes, with hubs in Moscow and Novosibirsk in Siberia, where it was founded.
The carrier is a member of the Oneworld alliance that also includes British Airways and American Airlines, though its membership has been suspended since the Ukraine invasion.