By Alwyn Scott and Andrea Shalal-Esa WASHINGTON/NEW YORK (Reuters) - The top U.S. transportation safety agency said on Tuesday it is looking beyond what caused a Boeing Co Dreamliner battery fire in January to find larger lessons that can be applied to the airplane certification process and to new technologies.

The European Aviation Safety Agency said Tuesday it had approved Boeing's proposed battery design change for its 787 planes, after a problem with overheating grounded the jetliner in January. The green light, which follows a similar move in the United States, will allow the "European operated aircraft to return to service as soon as the modification will be installed," the Germany-based agency said in a statement.

WASHINGTON (Reuters) - A top Boeing Co <BA.N> executive said on Tuesday it was too early to determine whether problems with the lithium ion batteries on its new 787 Dreamliner that led to the plane's grounding in January stemmed from a design error or some manufacturing problem. Mike Sinnett, Boeing's chief 787 engineer, told an investigative hearing of the National Transportation Safety Board that the batteries had been through thousands of hours of testing before the new airliner began flying, plus additional hours during flight testing.

US air-safety regulators on Monday said they would inspect more than 1,000 Boeing 737s for a faulty tail part that could cause a pilot to lose control of the jetliner. In a new safety headache for Boeing three months after its 787 Dreamliner was grounded worldwide, the Federal Aviation Administration said it would inspect the single-aisle 737s for improperly mounted pins on the tail and replace those found faulty. The FAA said the airworthiness directive (AD) would take effect on May 20 and "affects 1,050 airplanes of US registry."