In an action that has become a human rights embarrassment to the Carter administration, West Coast long shoremen are refusing to load a ship with 22,000 pounds of U.S. aerial bomb parts for the military regime in Chile.

Standing on the sidelines and cheering on the longshoremen are two members of Congress, several human rights groups and the seamen's union, whose members would have to sail the ship.

All charge that the proposed shipment represents a desertion by the administration of its own policies and frequent assertions of dedication to human rights.

In response, administration officials say Chile has a legally valid contract for the bomb parts. But they also concede that the administration has the authority to half the shipment for policy reasons.

At the State Department yesterday, the official line was that there are no present plans to cancel's Chile's order. However, some department sources said privately, "It's a safe bet that the wisdom of going ahead with this transaction is going to be reviewed."

Underlying the controversy has been strong and continuing criticism of the Chilean regime headed by President Augusto Pinochet. His government, which came to power in a bloody 1973 coup that saw the killing of Marxist President Salvador Allende, has been accused of murdering, torturing and imprisoning its domestic opponents.

In response to these charges, Congress passed legislation in 1976 cutting off all U.S. military aid to Chile. In addition, President Carter, who made concern for human rights a major issue in his presidential campaign, has followed a generally tough line in dealing with the Pinochet regime.

However, in line with what State Department officials described as "generally established practice," the administration has been allowing so-called pipeline military equipment - weapons and other material contracted for before the congressional ban went into effect - to be shipped to Chile.

Despite occasional complaints by human rights groups, these shipments didn't cause much of a stir until late in May when the International Longshoremen's and Warehousemen's Union (ILWU) received word that its locals in San Francisco would be called on to load the bomb parts aboard the SS Seajet in that port.

In 1975, the ILWU's annual convention called for a boycott of all cargo to and from Chile. Citing that internal resolution, the union refused to touch the bomb parts - identified by the Air Force as the tail assemblies for 25-pound practice bombs - after their arrival in San Francisco.

After the parts sat on the docks for several days, the government had them moved to a warehouse at the Oakland Army base. ILWU officials said yesterday they had received information that another vessel, the SS american charger, has been engaged to pick up the bomb parts at the Army base on or about June 25.

Andrew McLellan, inter-American representative of the AFL-CIO, said last night that the National Maritime Union (NMU), which represents the crew of the American Charger, also opposes transporting the bomb assemblies to Chile.

Accordingly, McLellan said, the NMU has instructed the crew to refuse any assistance to the loading. But, he added, if the government does get the shipment abroad, the crew will be required to sail the ship because a refusal to do so could be considered mutiny under maritime law.

In the meantime, the Chile Information and Legislative Center, a private, Washington-based organization that acts as a spokesman for human rights groups concerned with Chile, has been drumming up support for the longshoremen's stance.

By yesterday, that support included strong statements by Sen. Edward M. Kennedy (D-Mass.) and Rep. Phillip Burton (D-Calif.), who represents the San Francisco area.

Kennedy said that shipping the bomb parts would "run counter to the wishes of the majority of Congress and the American people." Burton said he "vigorously opposes" any military dealings with Chile and called for cancellation of "this back-door delivery of fin bomb parts."

State Department officials said yesterday they could not tell immediately how much equipment remained in the pipeline for Chile. However, Cindy Arnson, a researcher with the Institute for Policy Studies, a private Washington group that has done several critical studies on Chile, said her estimates indicated that the Pinochet regime had $120 million worth of orders in the pipeline at the time Congress imposed its ban in 1976.

Of that amount, Arnson said, approximately $57 million worth was shipped in 1977; and, she added, unless the administration changes its policy, the remainder is due to go this year.