WASHINGTON (AP) – Orders for long-lasting factory goods fell by the largest amount in three years last month, mostly because demand for commercial aircraft plummeted. But companies also ordered less machinery and other equipment, a sign manufacturing output may slow. The Commerce Department says orders for durable goods dropped 4.2 percent in March, the steepest fall since January 2009. Commercial aircraft orders, a volatile category, fell by nearly 50 percent. Excluding transportation equipment, orders declined 1.1 percent. That’s the second drop in that category in three months. And orders for so-called “core” capital goods, a good measure of business investment plans, declined 0.8 percent. Companies are reducing their orders for steel and other metals, industrial machinery and computers.