Twenty-three out of 41 Boeing 747 jumbo jets inspected in Japan after last week's Japan Air Lines crash were found to have abnormalities, the Ministry of Transport announced today, but it said they present no danger and that necessary repairs have been made.

Improvement in the Japanese airlines' procedures for inspecting aircraft will be necessary, however, the ministry added.

After the JAL crash Aug. 12, the ministry ordered checks of all jumbo jets in Japan, in particular the tail portion of the planes, where the difficulty with the downed airliner apparently originated.

Shiro Ooshima, deputy director general of the Engineering Department of the Civil Aviation Bureau, said at a press conference that the inspections had found a total of 35 problems in 23 planes of JAL and two other Japanese airline companies, including cracks and scratches, one or two broken bolts attaching the rear pressure bulkhead, loose bulkhead and rudder bolts, rust and worn bearings.

Ooshima said at the press conference that the inspection system must be improved. Under the present system, checks of the bulkhead and a sample number of bolts are required after 20,000 hours of flight. In the inspections after the crash, however, all bolts were checked individually.

The crashed JAL plane had flown more than 25,000 hours.