PHOENIX — 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.
Southwest finished inspecting all of its affected planes by Tuesday. They found five that had cracks in the same lap joint that tore open during last week's flight, and were working with Boeing to make repairs. Alaska Airlines is going a step beyond a Federal Aviation Administration directive this week that ordered inspections when the planes reach 30,000 takeoffs and landings; the airline will inspect all its planes in the coming weeks.
"We're not required to inspect them right now, but we felt it was the prudent thing to do, and to help the industry determine the proper interval," spokesman Paul McElroy said.
There are about 6,000 737s in operation worldwide, and an emergency FAA order on Tuesday only covers 579 that have the type of "lap joint" that failed during last week's flight. Lap joints are used in many places on an aircraft fuselage and get their name because it is the spot where the aluminum skin of the aircraft overlaps and is secured with rivets. The FAA order focuses on a Boeing joint design on planes made between 1993 and 2000.
Experts say that all of the planes around the world will be covered by the FAA order because of international agreements between civil aviation regulators globally. Many of the inspection orders handed down by foreign governments mirrored the one issued by the FAA.
"Some airlines may not always maintain the records that they need to and certainly not all airlines will not maintain their airplanes to the highest levels of safety," said Henry Harteveldt, aviation analysis at Forrester Research Inc. in San Francisco. "But I would make very clear that the top-tier U.S. and foreign flag airlines do this. Airlines like British Airways, Qantas and so on, those airlines maintain their airplanes to the highest standards and the best record-keeping."
The FAA said all of the planes have to undergo inspections when they reach the threshold of 30,000 takeoffs and landings. The 175 of those planes that have already reached the threshold are getting immediate inspections.
For example, the planes owned by the crown prince of Thailand and Chinese Air Force have only flown about 5,000 cycles each, meaning their planes have a long ways to go before an inspection. One of the Swedish planes has more than 40,000, requiring an immediate examination.
The inspections are high-tech and labor-intensive.
Mechanics using a device that sends magnetic signals through metal to detect unseen cracks will scan about 50 feet of the twin metal seams running along the top of each airplane. The task takes two experts in aircraft service about eight hours. Repairs on any fatigue cracks will take a day or two at most. The checks will have to be repeated every 500 flights.