WASHINGTON — The government shutdown that ended last month has taken a lasting hit on the Coast Guard, which has grounded aircraft, stopped major ship repairs and will leave parts of an air station in Puerto Rico without emergency generators for the start of hurricane season because of a backlog that will take months to process.

Internal documents obtained by The New York Times show that the Coast Guard’s ship maintenance command lost at least 7,456 productive workdays — or 28.5 years’ worth of workdays — as a direct result of the partial shutdown, which furloughed 6,400 civilian employees.

“This reality poses significant risk to operational availability of cutters and boats,” the documents concluded.

The service also noted a “domino effect” that has caused delays in repairs and maintenance on its roughly 200 aircraft, which, in turn, could keep them from being immediately available.