What was found
(AUS) NOSE LANDING GEAR WOULD NOT EXTEND - AIRCRAFT LANDED WITH NLG RETRACTED - INVESTIGATION FOUND THAT A NEW NLG WAS RECEIVEDWITHOUT THE TOP SECTION OF THE PROXIMITY SENSOR PROTECTIVE COVER - A NEW ONE WAS MANUFACTURED AND FITTED WITH HEXAGON HEADED BOLTSINSTEAD OF THE CORRECT COUNTERSUNK ITEMS REQUIRED BY THE MANUFACTURER - INTERNAL SPACERS WERE ALSO USED TO OBTAIN THE CORRECT INTERNAL CLEARANCE BETWEEN THE COVER AND THE PROXIMITY SENSORS - THE USE OF THE HEXAGON BOLTS AND SPACERS RESULTED IN THE BOLTS CONTACTING THE UPPER DRAG BRACE DURING NLG RETRACTION PREVENTING NLG EXTENSION - DAMAGE CAUSED TO THE UNDERSIDE OF THE AIRCRAFT - PERSONNEL/MAINTENANCE ERROR - UNAPPROVED PART