Because of erroneous information from a Northrop Corp. spokesman, some editions yesterday reported an incorrect estimate of the number of U.S. air-launched cruise missiles with a Northrop part that may have been improperly tested. One-half of the approximately 1, 800 ALCMs have the part. (Published 7/4/87)

The Air Force, recently stung by public revelations of shortcomings in the B1 bomber and MX missile programs, has begun an investigation into suspected defects in its nuclear-tipped air launched cruise missiles, or ALCMs, Air Force officials and congressional sources said yesterday.

The investigation centers on allegations that a key part of the cruise missile has been improperly tested by its manufacturer, the Northrop Corp., calling into question the missiles' ability to hit their targets in the Soviet Union in the event of a nuclear war, the officials said.

Northrop announced yesterday that it had removed four employes at the Pomona, Calif., plant that produced the parts, "pending the outcome of an investigation begun last week into possible irregularities in the testing of electronic components."

Law enforcement sources in Washington confirmed that the Justice Department's Fraud Section and the FBI are investigating the allegations.

Northrop has produced the component in question -- known as an "attitude stabilization unit" and intended to keep the missile on course during high-speed, low-level flights over Soviet territory -- for half of the roughly 1,800 cruise missiles in the U.S. strategic arsenal, according to congressional and industry sources.

Most of the missiles are deployed on B52 strategic bombers. Coupled with serious defects in some vital electronic systems of the new B1 bomber, the ALCM problems could mean that much of one leg of the U.S. strategic "triad" -- composed of air-, sea-, and land-based nuclear systems -- is potentially unreliable. Furthermore, the newest addition to the land-based leg, the MX missile, is suspect because of recent concerns raised about the weapon's guidance system, which also is made by Northrop.

Several sources said the ALCM allegations, apparently first raised by Northrop employes, centered on the company's failure to test an as yet undetermined portion of the attitude stabilization units after they were assembled.

Government investigators recently tested four of the parts in an effort to verify the allegations and each failed to operate as expected, according to one knowledgeable source. This report could not be independently confirmed.

Capt. Michael Laughlin, an Air Force spokesman, declined to provide details of the ongoing review by the agency's Office of Special Investigations, but said a team of experts will visit Northrop's Pomona plant soon.

Congressional sources complained that committees with jurisdiction over the cruise missile program were not told of the problems, even though Air Force field investigators have been looking into the allegations since February and officials in Washington have known of them for several weeks.

House Armed Services Committee Chairman Les Aspin (D-Wis.) told Air Force Secretary Edward C. Aldridge Jr. in a letter yesterday that his committee had learned of the allegations from "independent sources" and that they "raise basic questions about the management, oversight and performance of critical strategic modernization efforts."

"The allegations raise questions of confidence in the ALCM system, in particular, and in Northrop Corp. in general," Aspin wrote, noting that the company has recently been criticized by the Air Force for unduly slow delivery of guidance systems for the MX strategic missile and by his committee for problems in developing the new Stealth strategic bomber.

As a result of delays in production of the guidance mechanism, one-third of the existing 21 MX missiles cannot be fired, the Air Force said. Cost overruns and alleged security lapses in the Stealth bomber program have caused the House Armed Services Committee to demand that another company be allowed to share production of the plane.

Apparently responding to this criticism, Northrop announced yesterday that it had replaced the general manager and senior financial officer of the plant in Hawthorne, Calif., where the MX guidance mechanism is produced.

Thomas V. Jones, Northrop chairman, said in a statement on the personnel changes that "our customers rely on the integrity of our management and our adherence to procedures as much as on the quality of the systems we produce. We expect to meet their standards of excellence and our own, and we are going to do whatever is necessary, throughout the corporation, to make sure we do."

Aspin's letter to Aldridge, obtained yesterday by The Washington Post, said that the allegations included charges that the company may have "falsely certified" results of tests involving the cruise missile part. If true, he said, "the integrity and confidence in deployed {cruise} missiles is severely compromised."

The missiles, which cost roughly $1.5 million each, were developed by the Air Force because improvements in Soviet air defenses began to threaten the capability of B52 bombers to reach their targets. Without them, bombers would face considerably greater risk of destruction. Staff writer Howard Kurtz contributed to this report.