United Airlines says it found loose bolts while inspecting Boeing 737 Max 9 planes

United Airlines says it discovered loose bolts holding on door plugs like the one that blew out of an Alaska Airlines flight on Friday, causing the plane to make an emergency landing back at its originating airport. A representative for United who only identified themselves as “Erin” told The Verge in an email that since beginning inspections of the planes on Saturday, it has “found instances that appear to relate to installation issues in the door plug — for example, bolts that needed additional tightening.”

The Air Current first reported that United had found loose plugs on “at least” five aircraft. Now, United has confirmed the discovery and says its technicians will remedy the installation issues and “safely return the aircraft to service.” The company says it has 79 Boeing 737 Max 9 in its fleet.

Erin also wrote that service on the planes is suspended and that it has canceled 200 Boeing 737 Max 9 flights. United also expects “significant cancellations on Tuesday as well.”

United’s inspection process involves removing two rows of seats and the wall’s liner, which the company says it has already done on most planes. It says it then opens the door to inspect the surrounding area, including the seal, then closes it, “ensuring proper fit and security.” The company says five techs inspect each plane for several hours.

The FAA began requiring the inspections after the Alaska Airlines incident and has directed companies to repair any issues they find. Alaska Airlines said that it hadn’t found any concerning issues while inspecting the first quarter of its 737 Max 9 fleet.