AlHijjah 1, 1435, Sep 25, 2014, SPA -- Orders for U.S. durable goods posted their biggest drop on record in August due to volatile commercial aircraft sales, but a rebound in business spending plans suggested underlying strength in the manufacturing sector, the government reported Thursday. The Commerce Department said orders for durable goods—expensive manufactured items expected to last at least three years—plunged 18.2 percent last month, mostly reversing a 22.5 percent surge in July driven by aircraft demand. Orders for the volatile transportation category fell 42 percent in August as civilian aircraft orders tumbled 74.3 percent. Transportation orders had soared 315.6 percent the previous month. Boeing Company reported on its website it had received 107 orders last month, one-third of July's unusually large gains. Orders for automobiles fell 6.4 percent in August after increasing 10 percent the previous month. Excluding transportation, durable-goods orders rose 0.7 percent last month following a 0.5 percent decline in July. Non-defense capital goods orders excluding aircraft—a closely watched measure of business spending plans—rose 0.6 percent in August after falling 0.2 percent the previous month. Core capital goods shipments rose 0.1 percent following a 1.9 percent advance in July. The increase in core capital goods orders and the underlying trend in overall durable-goods orders suggest further gains are likely in coming months. Manufacturing is being supported by improving domestic demand, which is helping to offset some of the weakness due to slowing growth in the euro-zone and China.