U.S. aviation authorities have ordered emergency inspections of newer model Boeing Co. 737 jetliners in response to last week's explosion and fire that destroyed a China Airlines plane in Japan, officials said on Monday.

A Federal Aviation Administration order sent to airlines over the weekend requires wing slat inspections on all 737-600 through 900ER models within the next three weeks.

There are more than 780 of the affected planes registered to U.S. airlines and another 1,500 flying overseas. Foreign aviation safety authorities usually follow FAA recommendations.

Airlines were working diligently to complete the inspections, a Boeing spokesman said.

The FAA, working with Boeing, wants airlines to ensure that a nut inside the movable slat system on each wing does not fall off and possibly damage an adjacent fuel tank.

Slats are panels that extend from the front of the wing to help give an aircraft lift at lower speeds -- during landing and takeoff.

Japanese investigators examining the charred wreckage of the Taiwanese 737-800 on the island of Okinawa found that a loose nut fell into the path of a retracting wing slat after landing and pierced the fuel tank, causing a leak.

The leaking fuel triggered an explosion and fire that engulfed the plane but all aboard escaped safely.

Boeing said it issued a service letter to airlines in 2005 after receiving four reports of loose slat nuts. In one case, a nut fell off a bolt and punctured a fuel tank, but there was no fire. The advisory was updated in 2006 and again last month, Boeing said.

(Reporting by John Crawley)

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