Gregor said an FAA inspector from Phoenix was en route to Yuma. The NTSB said it also was sending a crew to Yuma.
Holes in aircraft can be caused by metal fatigue or lightning. The National Weather Service said the weather was clear from the Phoenix area to the California border on Friday afternoon.
In 1988, cracks caused part of the roof of an Aloha Airlines Boeing 737 to peel open while the jet flew from Hilo to Honolulu. A flight attendant was sucked out of the plane and plunged to her death, and dozens of passengers were injured.
Three years ago, an exploding oxygen cylinder ripped a gaping hole the fuselage of a Qantas Boeing 747-438 carrying 365 people. The plane descended thousands of feet with the loss of cabin pressure and flew about 300 miles to Manila, where it made a successful emergency landing. No one was injured.
Hoang, Associated Press writers Don Thompson and Adam Weintraub contributed to this report from Sacramento, Calif.