BAGHDAD - The V-22 Osprey has arrived in a combat zone for the first time.

It was an epic trip for the tilt-rotor plane, one that took more than 25 years of development and cost 30 lives and $20 billion. Even the last short hop - from an aircraft carrier into Iraq - went awry, U.S. military officials said yesterday.

A malfunction forced one of the 10 Ospreys that were deployed to land in Jordan on Thursday. The Marines flew parts to it from Iraq and repaired it. After it took off again Saturday, the problem recurred, and it had to turn back and land in Jordan a second time, said Maj. Jeff Pool, a U.S. military spokesman in western Iraq. The Osprey finally was repaired and arrived at Asad air base in western Iraq late Sunday afternoon.

Maj. Eric Dent, an Osprey spokesman at Marine headquarters in Washington, declined to identify the problem.

"The nature of the malfunction was a minor issue, but our aircrews are top-notch when it comes to safety," Dent said in an e-mail. "Rather than continue, the aircrew opted to land at a predetermined divert location and further investigate the issue."

Now the Osprey is on the world stage, and the burden of proving it is safe and effective in combat lies with the North Carolina-based Marine Medium Tiltrotor Squadron 263, nicknamed the "Thunder Chickens." The unit's mission will be transporting troops and cargo in western Iraq.

It will perform that mission in ways that no other military transporters have done in combat. The Osprey - which costs $110 million each, including development costs - takes off and lands like a helicopter but tilts its engines forward to fly like an airplane. It is jointly produced by the Boeing Co. in Ridley Township, Delaware County, and Bell Helicopter Textron of Fort Worth, Texas.

Its arrival in Iraq is aviation history, said Bob Leder, a spokesman for the Bell-Boeing partnership.

"This is a big thing - the introduction of a new type of aircraft into combat, totally different from the way things have been done before," he said.

Leder said the company believed that the Osprey and the squadron would do well but that years of criticism and heavy media attention were putting huge pressure on the unit to perform.

The aircraft's problems have generated a gallery of vocal detractors, who say that not only is it too expensive and too dangerous but that it performs poorly and has become little more than an extraordinarily expensive bus.

The Osprey made the cover of Time magazine last week in a highly critical article that called it "A Flying Shame."

The problem with the flight into Iraq recalled one of the V-22's first big journeys, a transatlantic flight last year to an English air show. One Osprey suffered engine problems and had to make a precautionary landing in Iceland.

The aircraft has had worse moments, though, including three fatal crashes:

In 1992, seven crew members died when a tilt-rotor crashed into the Potomac River.

In April 2000, a V-22 with 19 crew and Marine passengers aboard crashed in Arizona, killing all.

In December 2000, a mechanical problem compounded by a software glitch caused a crash in North Carolina that killed the crew of four.