B-2 Component Under Scrutiny, Northrop Says

Northrop disclosed Monday in its annual report that an electronic flight control system for the B-2 Stealth bomber is under investigation by the Department of Justice.

The system is called the Actuator Remote Terminal, a device that the Air Force was forced to upgrade while the B-2 has been grounded for modifications since late last year. The ART system has been plagued by severe technical problems, according to an informed source, though the Air Force has denied that the system is not working properly.

The ART plays a critical role in keeping the B-2 stable in flight. It takes commands from the bomber’s flight control computer, relays them to flight control surfaces and then provides feedback information to the computer. The B-2, which has an unconventional all-wing design, relies on its computers to maintain stability and without the computers would be unstable.

Air Force officials said in a recent interview that “the flight control system, including the ART, is performing better than expected. We are taking advantage of the scheduled layup to upgrade the ART system. We are installing a faster microprocessor with a bigger memory.”

Asked why the Air Force would be changing the system if it were working well, the spokeswoman said the service wanted to “take advantage of the scheduled layup in the test program to upgrade the system.”

Northrop disclosed the Justice Department investigation, saying that its recent guilty plea on unrelated criminal charges provided for the government to drop certain investigations at the company but specifically not the one involving ART.

The ART was produced by Lear Astronics of Santa Monica, the Air Force said. Lear officials did not return a reporter’s call.

The B-2 is undergoing modification during a five-month grounding, but Air Force officials said the grounding was planned as part of the bomber’s flight test program. The next step in the flight test program will be testing of the aircraft’s ability to evade radar.

A Northrop spokesman said flight tests are due to resume later this month.

In addition to changing the ART, the Air Force is changing some rivets on the B-2, strengthening the wings after discovering some weaknesses and installing an autopilot system that has not yet been tested, the Air Force spokeswoman said. The service is also installing improved power units that experienced cracks in their cases early in the test program.