In a revealing demonstration of how Egypt's national psychology and political orientation are being reshaped by the reality of peace, a team of air defense experts from the Pentagon is due here Saturday for a two-week inspection of Egypt's deteriorating Soviet-built anti-aircraft missiles.

In the Egyptian context, it is little short of revolutionary for the armed forces to permit American military personnel even to approach Egyptian military installations, let alone undertake this detailed scrutiny of critical weapons.

Egypt's Soviet-trained armed forces traditionally have been a closed book to outsiders and especially to representatives of the country the Egyptians hold responsible for building the Israeli military machine.

With the advert of peace, however, the Egyptians and the Americans suddenly have become partners in exactly the way President Anwar Sadat envisoned when he first begain to diversify his weapons sources after breaking with the Soviet Union. The United States is becoming ever more deply involved in promoting Egypt's economic and military development.

Egypt already possesses American propeller-driven transport planes. It is expecting the first shipment of F5 fighters this year, although Saudi Arabia, which has promised to pay for them, has not yet come up with the money, according to military sources.

A small group of U.S. Air Force personnel and civilian technicians is already here supervising those two programs and instructing the Egyptians. But the missile inspection gives the United States new access to information about Egypt's most critical defense systems that would have been unthinkable in the past-numbers, locations and conditions of missiles that Egypt has taken elaborate precautions to conceal from American Satellite Camers.

A spokesman for the U.S. Embassy said, "The U.S. governmet has agreed to dispatch a teach of air defense experts of Egypt to consult with the government of Egypt on air defense requirements. The team will discuss those requirements in detail and will report back to the secretary of defense."

According to military sources, the American team, headed by an Army colonel, will make estensive on-site inspections of Egypt's antiaircraft defenses and prepare an assessment of Egypt's needs for new equipment. It is likely, the suorces said, that Egypt will want to use some of the $1.5 billion in military aid that President Carter has proposed to purchase batteries of the U.S. made Hawk missile system to replace its aging Soviet SAMs.

Egypt's air defense command is a separate branch of the armed forces, with an estimated of the armed forces, with an estimated 75,000 men. The heart of its equipment is about 600 SAM2, SAM3 and SAM6 missiles supplied by the Soviet Union before Moscow cut off arms supplies to Egypt in 1975.

Military experts here believe many of those Soviet missiles have deteriorated after years of exposure to desert winds and sand and may no longer be operational. Even if they are, Egypt faces an acute problem in keeping them that way because of a shortage of spare parts.

Sadat has made no secret of Egypt's need for new air defense equipment. But the Egyptians have been restricted to what they could afford from Western suppliers, who wanted payment in hard currency. Egypt is awaiting delivery of its first battery of French-built Crotale missiles, but is expected to ask the United States for Hawks as well.

In another sign of Egypt's growing military relationship with the United States, a team of Egyptian Air Force officers is to visit the United States next month to see what combat jets might be available in addition to the F5s. Egypt is believed to be willing to settle for the F4 Phantam if it cannot get the more advanced F15 or F16. But since the Phantom production line is all but shut down, it may be necessary for Egypt to select used aircraft from American surplus, military sources here said.