The B-2 bomber, which long has battled bad reviews, suffered what might have been a bolt of bad luck recently, when lightning apparently zapped a wing of one of the fleet and caused as much as $1 million in damage.

The Air Force said Friday that it still had not determined precisely what caused small blisters to appear on the super-costly radar-evading material in which the $2 billion plane is encased. But lightning was being considered as a likely culprit.The bat-winged craft was damaged March 25 during a routine training flight at Whiteman Air Force Base in Missouri, where the B-2s are based, according to the service. Whiteman officials estimated it would cost somewhere between $500,000 and $1 million to fix the holes in the material.

Officials said it was not clear how the plane, which remains able to fly, was damaged. It is one of 18 B-2s in the U.S. fleet. Eight are operational. The damaged plane is still able to fly, but its radar-dodging capacity has been hurt, a Whiteman spokesman said.

This bad news for the B-2, which even the Pentagon has criticized for being overpriced and beset with problems, came just days after the Air Force trumpeted the success the bomber had during its first real deployment.

In March, two of the so-called "stealth" bombers were dispatched to Anderson Air Force Base in Guam, marking the first time the plane had been sent so far from its home base.

The Air Force was pleased to report that at least one of the bombers had been parked outside in the tropical weather, and was exposed to both intense sunlight and heavy rainstorms.

Even so, each of the planes managed to drop a maximum payload of 80 Mk-82 bombs with "pinpoint accuracy," the Air Force said.

That might not seem like much to brag about, but considering the problems that have beset the B-2 since it became operational last April, that ranks as good news.

Last August, the Air Force acknowledged that the supercraft was so sensitive to outdoor temperature and moisture that it could not be deployed overseas.