Narrative:

Flight xyz departed ZZZ. Everything normal en route to ord. On approach to runway 14R, gear extended with nose gear lights extinguished and gear not latched light illuminated. Recycled gear while on approach. No change in gear indications. Initiated go around, cleaned flaps up and left gear extended and tested gear light bulbs. Bulbs checked good. Ran the 'gear unsafe indication' checklist. Visually inspected nose gear indices and noted that they were not aligned. Contacted maintenance and ZZZ for further guidance. Per maintenance's instructions, we accomplished the following: 1) extended gear while applying a positive g-load on the aircraft. 2) performed a high airspeed (300 KTS) extension of the landing gear accompanied with yawing of the aircraft. 3) attempted free-falling of landing gear with hydraulic pressure removed from the aircraft. After the above procedures were performed, a visual inspection of the nose gear indices produced no changes. Performed all required checklists per DC8 aom. Declared an emergency with ATC and made a normal approach to runway 32R at ord. Normal landing was made, gently lowering the nose of the aircraft to the runway. Upon brake application, right main tires were blown. Aircraft remained just right of centerline. Upon stopping, #1 and #4 engines were secured. Subsequently fire and rescue notified the crew that the right main tires were on fire. Initiated 'emergency evacuate/evacuation' checklist. Deployed entry door slide. While preparing to evacuate/evacuation via the slide, the nose gear collapsed. When egressing the aircraft, the first person who jumped on the slide caused the slide mounting brackets to fail. The slide and the girth bar separated from the aircraft. The rest of the crew and the acm exited the aircraft uneventfully. Callback conversation with reporter revealed the following information: the reporter stated the nose gear would extend but would not lock in the down position. The reporter said the cause was a migrating bushing in the lock links where the down lock pin is inserted. The reporter said the bushing migrated out and prevented the lock links from straightening out in the lock position.

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Original NASA ASRS Text

Title: A DC8-71 EXPERIENCES NOSE LNDG GEAR UNSAFE INDICATION AND ON LNDG ROLLOUT THE NOSE GEAR COLLAPSES CAUSED BY THE NOSE GEAR LOCK LINK BUSHING FAILURE.

Narrative: FLT XYZ DEPARTED ZZZ. EVERYTHING NORMAL ENRTE TO ORD. ON APCH TO RWY 14R, GEAR EXTENDED WITH NOSE GEAR LIGHTS EXTINGUISHED AND GEAR NOT LATCHED LIGHT ILLUMINATED. RECYCLED GEAR WHILE ON APCH. NO CHANGE IN GEAR INDICATIONS. INITIATED GAR, CLEANED FLAPS UP AND L GEAR EXTENDED AND TESTED GEAR LIGHT BULBS. BULBS CHKED GOOD. RAN THE 'GEAR UNSAFE INDICATION' CHKLIST. VISUALLY INSPECTED NOSE GEAR INDICES AND NOTED THAT THEY WERE NOT ALIGNED. CONTACTED MAINT AND ZZZ FOR FURTHER GUIDANCE. PER MAINT'S INSTRUCTIONS, WE ACCOMPLISHED THE FOLLOWING: 1) EXTENDED GEAR WHILE APPLYING A POSITIVE G-LOAD ON THE ACFT. 2) PERFORMED A HIGH AIRSPD (300 KTS) EXTENSION OF THE LNDG GEAR ACCOMPANIED WITH YAWING OF THE ACFT. 3) ATTEMPTED FREE-FALLING OF LNDG GEAR WITH HYD PRESSURE REMOVED FROM THE ACFT. AFTER THE ABOVE PROCS WERE PERFORMED, A VISUAL INSPECTION OF THE NOSE GEAR INDICES PRODUCED NO CHANGES. PERFORMED ALL REQUIRED CHKLISTS PER DC8 AOM. DECLARED AN EMER WITH ATC AND MADE A NORMAL APCH TO RWY 32R AT ORD. NORMAL LNDG WAS MADE, GENTLY LOWERING THE NOSE OF THE ACFT TO THE RWY. UPON BRAKE APPLICATION, R MAIN TIRES WERE BLOWN. ACFT REMAINED JUST R OF CTRLINE. UPON STOPPING, #1 AND #4 ENGS WERE SECURED. SUBSEQUENTLY FIRE AND RESCUE NOTIFIED THE CREW THAT THE R MAIN TIRES WERE ON FIRE. INITIATED 'EMER EVAC' CHKLIST. DEPLOYED ENTRY DOOR SLIDE. WHILE PREPARING TO EVAC VIA THE SLIDE, THE NOSE GEAR COLLAPSED. WHEN EGRESSING THE ACFT, THE FIRST PERSON WHO JUMPED ON THE SLIDE CAUSED THE SLIDE MOUNTING BRACKETS TO FAIL. THE SLIDE AND THE GIRTH BAR SEPARATED FROM THE ACFT. THE REST OF THE CREW AND THE ACM EXITED THE ACFT UNEVENTFULLY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE NOSE GEAR WOULD EXTEND BUT WOULD NOT LOCK IN THE DOWN POS. THE RPTR SAID THE CAUSE WAS A MIGRATING BUSHING IN THE LOCK LINKS WHERE THE DOWN LOCK PIN IS INSERTED. THE RPTR SAID THE BUSHING MIGRATED OUT AND PREVENTED THE LOCK LINKS FROM STRAIGHTENING OUT IN THE LOCK POS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.