The Financial Post reports in its Monday edition that the U.S. government hit Boeing with a proposed $3.9-million fine on Friday, saying the firm installed substandard parts on 133 aircraft and did not properly oversee its suppliers. A Bloomberg dispatch to the Post quotes the Federal Aviation Administration saying that the parts in question were installed on the wings of Boeing 737 jets to allow devices known as slats to move back and forth. The civil penalty comes as the company has been embroiled in controversy over how it designed its 737 Max, which was involved in two fatal crashes that killed 346 people and has been grounded since March 13. Friday's proposed fines are not related to those accidents. On Friday, the FAA alleged Boeing "knowingly" sought FAA certification of aircraft that had the faulty parts, after determining the devices had failed a strength test. The so-called slat tracks, supplied by subcontractors, had become brittle during a process to add a cadmium-titanium plating, the FAA said. Boeing has 30 days to respond to the FAA and may dispute the allegations. The regulator often negotiates to lower penalties, particularly if companies agree to take steps to address the issue.