MOSCOW, RUSSIA — Contrary to expectations, the Russian commercial aviation industry has so far managed to keep its business afloat despite western sanctions that prevented the country from accessing essential spare parts and maintenance services.

The country's domestic air travel has recently bounced back sharply and approached pre-pandemic levels. But it causes safety concerns in the industry, especially in the west, since Boeing, Airbus, and other western suppliers, including engine manufacturers, ceased exporting critical parts and providing maintenance support to their Russian counterparts after the invasion of Ukraine.

International connections of the Russian airline operators are still far below 2019 levels as they were banned from using the airspace of most countries except China, Turkey, former Soviet Union states, and some states in Africa and Asia.

Before the war, 70 percent of the fleets of Russian operators (880 aircraft) consisted of aircraft from Airbus and Boeing. Around 500 of these planes had been leased from western lessors. After the sanctions, those lessors attempted to retrieve their aircraft from the country, but they failed. Most of the planes are still held and operated by Russian airlines.

"We are worried about the conditions for maintenance as the planes are flying a lot. Because of the sanctions, we cannot monitor and support as we do with our customers at normal times. And that's something that is indeed creating some concerns on the safety side," Guillaume Faury, chief executive of Airbus, told reporters last month.

Since the maintainability of aircraft has improved significantly over the past few years, most Boeing and Airbus aircraft can operate without too much maintenance in the short term, but spare parts, tooling, and equipment are quite a bit specific, and the problem is expected to grow over time. Russian airlines are already using some aircraft as spare parts sources. As time passes, they may be forced to acquire some third-party components from other countries or manufacture their own.

Each aircraft has its own maintenance planning and tracking document kept by its owner, and it must be updated after each maintenance operation. After the Russian government's decision to deregister the western-owned aircraft, the future of these planes became uncertain. Western lessors lost track of the maintainability state of their own aircraft. If Russia agrees to return those planes to their owners, It is doubtful whether they would want them back. Because these aircraft are now out of a legally controlled environment, and putting them into service in other parts of the world is not a simple issue."

"There is a difference between whether the aircraft can still fly and whether it meets international safety standards," said an executive of a Western lessor.

After failing to reclaim their aircraft from Russia, several lessors filed lawsuits against their insurers to recover their losses that cost billions of dollars.