BOB CHRISTIEPHOENIX (AP) â¿¿ The crown prince of Thailand has one. So do the presidents of Peru and Chile. The Chinese Air Force relies on it, as do airlines in Russia, Indonesia, Australia and Romania. The Boeing 737 is a workhorse of international aviation. And the accident in which the roof of a Southwest Airlines jet ripped open 34,000 feet over Arizona has brought scrutiny to the hundreds of older-model 737s around the world that could be similarly vulnerable because of tiny, hard-to-find stress fractures in the aluminum skin. The planes will now be subjected to repeated examinations as the problem revealed by the fuselage crack on the Southwest flight resonates through the world's 737 fleet for years to come. Many of their owners are now giving the planes a closer look after what happened April 1 in Arizona when a 5-foot section of the fuselage tore apart and forced pilots to make an emergency landing at a desert military base. Light-headed passengers were banged around the cabin and had to quickly put on overhead oxygen masks as pilots made a rapid descent. The incident has forced airlines and governments around the world to take swift action. The governments of Japan, Indonesia, South Korea and others ordered airlines to beef up inspections. Scandinavian airline SAS is performing similar checks on some of its 737s. Qantas Airlines in Australia is checking four of its planes and Air New Zealand is looking at 15. Airlines said the inspections have not disrupted air travel. Southwest and Continental Airlines have the most planes on the list of 737-300s, 737-400s and 737-500s prone to the fuselage ruptures, but a large number of the planes are owned by overseas carriers. UTAir in Russia, Garuda Airlines in Indonesia, Air New Zealand and three major carriers in China are among the biggest. Alaska Airlines has 17.