MECHANIC FALLS, Maine — Maine, like most states, doesn't have strict regulations for hayrides, including the one that lurched down a steep hill and into a tree over the weekend, killing a 17-year-old girl and injuring more than 20 others.

A mechanical problem caused a Jeep towing a wagon full of passengers in Mechanic Falls to crash during a Halloween-themed hayride at Harvest Hills Farm on Saturday, authorities said.

Maine doesn't have statutes that regulate hayrides, the state fire marshal's office has said.

Rhode Island is the only state that appears to explicitly require a permit to operate hayrides, said James Hanseen, a transportation researcher at the National Conference of State Legislatures.

In Pennsylvania, the Department of Agriculture inspects amusement rides, but operators will often argue that hayrides don't fall into that category because they're being used on private property, said Jeffrey Reiff, a Philadelphia lawyer who represents people injured in amusement park accidents.

SAN FRANCISCO — A Dallas-bound American Airlines flight that departed from San Francisco International Airport turned back and made an emergency landing after some of the cabin's wall panels cracked loose, aviation and airlines officials said.The captain of the Boeing 757 decided to turn around an hour into the flight to Dallas/Fort Worth International Airport because of a possible blown air duct, American Airlines spokesman Matt Miller said.Flight 2293 departed from SFO shortly before 1 p.m. Monday and landed without incident about 2:15 p.m. No one on the plane with 184 passengers and six crew members was hurt, he said.Even though the plane's problem is related to pressurization, the cabin did not lose pressure and oxygen masks did not deploy.Flight attendants said the problem was “cosmetic,” a passenger said.Experts agreed with that assessment and said that while it is disconcerting for passengers to see any piece of the plane break, the cabin's wall panels are not part of the structure.