SUMMARY OF INFORMATION FROM MANUFACTURER:NISSAN STATES THAT RUBBING AIRBRAKE LINE IS WRAPPED WITH COILED STEEL WIRE WHICH PROTECTS IT FROM FOREIGNOBJECT.IF FITTING IS LEFT UNCHANGED, IT WOULD TAKE YEARS BEFORE HOSESHOWED ANY SIGNS OR RUBBING OR ABRASIONS.MAINTENANCE MANUAL REQUIRES THATTHE BRAKE HOSE BE REPLACED AT 30,000 MILES OR 1 YEAR.RECALL (87V-056)CONCERNING WIRE HARNESS HAS BEEN ISSUED.ANALYSIS:THE SUBJECT AIR BRAKE HOSE IS WRAPPED WITH A COILED STEEL WIREAND REPLACEMENT AFTER 12 MONTHS IS REQUIRED BY THE SERVICE MANUAL.IT THEPROBLEM IS IGNORED OVER AN EXTENDED PERIOD OF TIME, SOME LOSS OF REAR BRAKEPOWER MAYEVENTUALLY OCCUR.LOW AIR PRESSURE WARNING DEVICE AND REAREMERGENCY BRAKES WOULD BE ACTIVATED.FRONT BRAKES NOT AFFECTED.A PRODUCTIMPROVEMENT LETTER HAS BEEN ISSUED ON THE BRAKE HOSE.PROPOSED ACTION:CLOSE THIS PE.===