U.S. orders for manufactured durable goods such as airplanes and computers declined in May for the second straight month, suggesting a loss of momentum in the U.S. manufacturing sector, U.S. Commerce Department reported on Monday.

Orders for durable goods fell by 1.1 percent from April to a seasonally-adjusted 228.2 billion U.S. dollars in May, the department said. It was the largest decline in six months and followed a 0.9 percent decline in April.

Orders for defense aircraft declined by 30.8 percent last month, while orders for civilian airplanes fell by 11.7 percent, the department said. Excluding transportation, durable goods orders increased 0.1 percent last month.

Orders for nondefense capital goods excluding aircraft, a key measure of business investment, dropped by 0.2 percent last month. It was the largest decline since December and suggested soft business investment in the second quarter of the year.

The manufacturing index, also known as the purchasing managers index (PMI), registered 54.9 in May, slightly up from the April reading of 54.8, according to the Institute for Supply Management (ISM). A reading above 50 indicates the sector is generally expanding, while a reading below that level indicates contraction.

The recent weak reports of durable goods orders and manufacturing production suggest that economic growth in the second report might not be as strong as expected.

The U.S. economy grew at an annual rate of 1.2 percent in the first quarter of this year, lower than the 2.1 percent growth in the previous quarter, according to the Commerce Department.