The commander in charge of the Titan II missiles at Little Rock Air Force Base has been replaced in a disciplinary action related to the explosion last September at the Titan site near Damascus, Ark., that killed one airman and injured 21 others.

The transfer order of Col. John T. Mosher, announced Wednesday at the base, was one of several actions taken by the Strategic Air Command since the accident occurred to meet complaints about operation of the 18-year-old, liquid-fueled, missile system. Among the others:

A siren warning system, just months ago described by SAC as too costly and unnecessary for the protection of civilians living or working near the 54 Titan sites, is being developed for each missile complex.

Every portable tool carried into the silo, according to a new SAC directive, must be tied on a lanyard and attached either to the airman using it or the silo wall.A dropped wrench socket punctured the Titan II's fuel tank and started the Damascus accident.

A costly, remote moinitoring system is being studied for placement in each underground silo so that in case of a spill or leak, vapor levels could be read from above ground without having to send men into the missile complex.

The announcement that Mosher had been relieved after only six months at the Little Rock base was greeted by several survivors of the accident with the comment that "the wrong man got fired," according to one source.

A Pentagon official said that Mosher's removal as Little Rock commander related more "to how he handled matters after the accident occurred than during the accident itself." He said top SAC officers believed "he was just a guy over his head when put in the spotlight." Another official noted that SAC had a record of replacing Titan commanders after major accidents, pointing out the same thing happened after the Rock, Kan., oxidizer spill in August 1978 in which two airmen died.

Relieving Mosher of his Titan command, however, revived complaints among some airmen involved that the accident had been incorrectly handled by the vice commander of SAC, Lt. Gen. Lloyd R. Leavitt Jr. At issue has been Leavitt's order that two teams reenter the missile complex to measure the toxic vapor levels six hours after the fuel began to spill out from the missile.

The airman who died, David Livingston, was one of the four men involved in the entry operation. The other three were severely injured.

Mosher and experts from Martin-Marietta Co., builders of the missile, had initially recommended against entry during a conference call with Leavitt, according to individuals who were party to the discussions.

SAC officials have said recently that tapes of telephone conference calls held the evening of the accident will show that Mosher and his colleagues at the Little Rock base and the Martin-Marietta experts "concurred" in Leavitt's decision.

A 1,400-page report of the accident investigation of the Damascus incident has just been completed and is being sent to 8th Air Force headquarters for reveiw and ultimate public release, according to a SAC public affairs officer. He could not say whether the taped conversations would be part of that record. This report is expected to contain interviews with airmen and others who were at the scene.

Another report, by the Air Force Safety and Inspection Center, is expected to be released this week. It focuses on operation of the Titan systems that worked and did not work.

Both the House and Senate Armed Services committees have been looking into the Titan II system, studying whether it should be kept opeational given the troubles that have been occurring at the missile sites.

A third study of the system, by the Air Force under direction of President Carter, is expected to report on what actions must be taken to make the system safe for continued operation.

When that study comes in early next year, both congressional committees are expected to take a hard look at whether the money needed to make it safe is worth the benefits that come from the missile system's enormous nuclear explosive power.