Crack-inspecting drone crashes outside sinking Millennium Tower

The Millenium Tower is visible out the windows at the Salesforce Tower in San Francisco, Calif., Thursday, November 2, 2017. The Millenium Tower is visible out the windows at the Salesforce Tower in San Francisco, Calif., Thursday, November 2, 2017. Photo: Carlos Avila Gonzalez / The Chronicle Buy photo Photo: Carlos Avila Gonzalez / The Chronicle Image 1 of / 19 Caption Close Crack-inspecting drone crashes outside sinking Millennium Tower 1 / 19 Back to Gallery

A drone being used to inspect a cracked window in the famously sinking Millennium Tower crashed Saturday, according to a report, adding to the building’s notoriety.

KPIX-TV reported that a drone deployed to photograph and inspect the crack in the glass on the 36th floor of the building lost its signal and crashed to the street after capturing footage of the crack.

No one was injured, according to the TV report, but a young boy was quoted as saying he was nearly hit.

The crack, discovered last week, could be an isolated break or a sign of a more serious problem caused by the sinking and tilting of the 58-story building, an architectural engineering firm told city officials Friday.

Since opening in 2009, the Millennium Tower has sunk by around 18 inches and tilted to one side, prompting serious concerns about the building’s structural integrity.

A report from engineering firm Allana Buick & Bers was filed late Friday with the city’s Department of Building Inspection. It says someone will rappel down the building early next week to photograph the crack from the outside and to tape up the glass as a safety precaution.

Michael Cabanatuan is a San Francisco Chronicle staff writer. Email: mcabanatuan@sfchronicle.com Twitter: @ctuan