By David Shepardson, Valerie Insinna and Tim Hepher (Reuters) – Safety checks on some Boeing jets hit a snag over paperwork on Sunday, as U.S. authorities searched for a missing panel that blew off a new Boeing 737 MAX 9 jet in midair on Friday. The Federal Aviation Administration on Saturday ordered the temporary grounding of 171 Boeing jets installed with the same panel after the eight-week-old Alaska Airlines jet was forced to make an emergency landing with a gap in the fuselage. “They will remain grounded until the FAA is satisfied that they are safe,” the agency said in a statement on Sun…