The Air Force temporarily grounded its B1 bombers yesterday to inspect the planes' emergency ejection system after a crash last week in which three crew members were killed and three others escaped.

Air Force maintenance crews will inspect the emergency escape system on each of the 69 long-range B1 bombers before the planes will be allowed to return to service, according to a spokesman for the Strategic Air Command (SAC), which controls the bomber fleet.

Air Force officials said the "precautionary inspection" was a result of problems with the escape system in the bomber that crashed into the Colorado plains last week after birds were sucked into two engines.

Although the bomber has four ejection seats and an escape hatch in its floor, only three of the six crew members were able to eject and parachute to safety, Air Force officials said.

The escape system problems are the latest setback for the troubled $28.3 billion, 100-bomber program, which is a key to the Reagan administration's strategic forces buildup. The Air Force is grappling with major deficiencies in the electronic countermeasures system designed to protect the plane on bombing missions into the Soviet Union.

There also have been problems with development of the bomber's terrain-following radar and flight controls. Soon after the first bombers were declared combat-ready last fall, fuel leaks developed in the wings, where much of the bomber's fuel is stored. Air Force officials say they have corrected most of the leak problems.

Air Force officials said they are uncertain how long it will take to complete the inspections of the emergency escape systems in all the bombers. A SAC spokesman said that an inspection of one plane at Dyess Air Force Base near Abilene, Tex., was completed yesterday. The spokesman said each inspection takes about two hours.

The B1 bomber's escape systems can be operated either automatically or manually. In an emergency, the pilot or copilot can start the automatic ejection process by pulling a handle located about mid-thigh on their seats.

The chain reaction that follows takes about 2.5 seconds from the time the handle is pulled until the last crew member is ejected.

The crew members are ejected at half-second intervals with the officer who controls offensive weapons from the right rear seat ejecting first, followed by the defensive systems operator in the left rear seat, the copilot in the right front seat and the pilot in the left front seat.

The crew members who were killed in the training flight crash last week were the student pilot, the student defensive systems officer and the offensive systems instructor. Air Force officials refused to say where they were seated in the plane.

The crew members also could have ejected manually, with each pulling his seat ejection handle. Parachutes are built into the backs of four of the the plane's seats.

The B1 normally carries four, but in the case of the crashed B1 training flight, two additional crew members were seated in jump seats, which are not equipped with parachutes. Those two would have had to escape through a floor hatch just behind the cockpit.