(Web Desk) - United Airlines said it has found loose bolts and other parts on at least five of its Boeing 737 Max jet door plugs, the same fuselage piece that broke away from an Alaska Airlines jet on Friday.
"Since we began preliminary inspections on Saturday, we have found instances that appear to relate to installation issues in the door plug – for example, bolts that needed additional tightening," it said in an emailed statement to The Messenger.
United said it was able to tighten the loose parts and "safely return the aircraft to service."
Trade publication the Air Current reported the loose bolts on United's jets earlier Monday, citing three people familiar with the findings.
The Federal Aviation Administration hasn't yet lifted the grounding on all 737 Max 9s.
The door plug is used to cover what would be an emergency exit for airlines that carry the maximum number of passenger aboard their 737 Max 9 aircrafts. Alaska and United, two of the U.S. operators out of the 11 that fly the 737 Max 9, don’t use the cabin’s maximum seating density and conceal the exit with the plug, which appears as a normal sidewall and window.
The report caused a further dip in shares of Boeing and Spirit AeroSystems, which manufactures the fuselage of the 737 Max family for Boeing. Spirit dropped around 11% in late-day trading, while Boeing declined 8%.
The National Transportation Safety Board on Monday released photos of the plug door from the Alaska Airlines 737, which was recovered Sunday from the yard of a man who lives near the Portland airport.
The plug’s failure on the Alaska Airlines flight from Portland to Ontario, California, on Friday quickly led the Federal Aviation Administration on Saturday to ground 171 MAX 9s that are registered to U.S. airlines or fly in U.S. airspace.
On Sunday, European regulators adopted the same emergency directive but said none of the carriers it oversees is believed to use those plugs.
The FAA directive affects 144 Boeing 737s that United — with the largest number of that model in its fleet — and Alaska fly, leading to hundreds of cancellations over the past three days