* US durable goods orders unexpectedly fall

* Dollar index off 11-year high ahead of Fed

* Aussie could slip if inflation softer than forecast

By Hideyuki Sano

TOKYO, Jan 28 (Reuters) – The dollar stepped back from a 11-year peak against a basket of currencies after soft spending data and some disappointing earnings cast doubts about the underlying optimism on the U.S. economic outlook.

Investors took profits from recent gains in the U.S. currency ahead of the Federal Reserve’s policy announcement later in the day, which they think could show a more dovish bias due to the recent plunge in oil prices.

The dollar index posted its biggest fall since early October on Tuesday and slid to 94.010, off a 11-year high of 95.481 hit on Friday.

Against the yen, the U.S. currency was little changed at 117.87 yen, but off last week’s high of 118.80.

The euro ticked up to $ 1.1362, extending its rebound from a 11-year low of $ 1.1098 hit on Monday.

“I would say the dollar selling we’ve seen so far is just position adjustments ahead of the major (Fed) event,” said Bart Wakabayashi, head of forex at State Street Bank.

“But I am a bit nervous that the dollar may have a further leg to go down if the Fed says something negative (about the U.S. economy) given that the market is still very long in the dollar on the whole,” he added.

Indeed the dollar index is still up more than 4 percent so far this year, and up almost 18 percent since June, as investors have bet the Fed will start raising rates this year on the back of a solid U.S. economic recovery.

But data on Tuesday showed non-defense capital goods orders excluding aircraft, a closely watched proxy for business spending plans, fell unexpectedly for a fourth straight month in December.

It marked the longest downward stretch since 2012, stoking worries slowing global growth and cheap oil prices are curbing business spending in the U.S., seen as one of the brightest spots in the global economy.

While other U.S. data, such as consumer spending and home sales, were more robust, traders are getting worried the Fed could turn even more cautious in its guidance of future rate hikes given plunging oil prices are cooling any inflationary pressure.

The dour business investment report came as construction and mining equipment maker Caterpillar Inc reported a nearly 25 percent decline in fourth-quarter profit and warned that falling oil prices would hurt its business in 2015.

Elsewhere, the Australian dollar could face renewed pressure if the local consumer price data due at 0030 GMT comes in weaker than expected.

The Australian dollar traded at $ 0.7922, not far from 5 1/2-year low of $ 0.7850 touched on Monday.

(Editing by Shri Navaratnam)