A DC9-50 had the nose landing gear collapse on landing due to incorrect installation of interim repa...

Narrative:

On aug/xx/96, at the start of shift #1, lead mechanic was assigned to the 2 aircraft that were in the hangar for a service check and a 'C' check. Aircraft X which was in for a service check needed to be finished. Abcd, the manager on duty instructed me to replace the temporary flex line that was installed on the left steering actuator. I assigned a mechanic to see which line needed to be replaced. The mechanic looked up the part and found out there were no replacement parts in supply. I notified abcd about the situation. Abcd instructed us to have it removed so he could bench check it on the test stand. The leak check was ok so he said to put it back on the airplane and see if it leaks again. The mechanic hooked up the line and it started leaking again. The mechanic and I went up to see abcd in the manager's office to find out what he wanted done next. Abcd said to take out the line and resecure everything. The mechanic accomplished the resecuring, but I did not get to see the final close up. Callback conversation with reporter revealed the following information: reporter was contacted and revealed the following details. The nose gear collapse was a direct result of the flexible hose installed in the left nose gear steering cylinder hydraulic circuit. The flexible hose prevented the nose gear down and lock linkage from going over-center thus preventing a down and locked condition. The reporter believes the flexible hose installed as an interim repair for a leaking solid tube was too long and could not be clamped adequately. Callback conversation with acn 343596 reporter revealed the following: the nose gear collapse was caused by the flexible nose steering line interfering with the down lock mechanism. This flexible hydraulic hose was installed as an interim repair for a leaking hard line. The reporter states he made the first installation of the hose. On the overnight layover the line was removed with the hard line tubing for a bench check. The line bench checked ok, but leaked again on the airplane and the interim repair flexible hose was reinstalled.

Original NASA ASRS Text

Title: A DC9-50 HAD THE NOSE LNDG GEAR COLLAPSE ON LNDG DUE TO INCORRECT INSTALLATION OF INTERIM REPAIR HYD FLEX LINE INTERFERING WITH DOWN-LOCK MECHANISM.

Narrative: ON AUG/XX/96, AT THE START OF SHIFT #1, LEAD MECH WAS ASSIGNED TO THE 2 ACFT THAT WERE IN THE HANGAR FOR A SVC CHK AND A 'C' CHK. ACFT X WHICH WAS IN FOR A SVC CHK NEEDED TO BE FINISHED. ABCD, THE MGR ON DUTY INSTRUCTED ME TO REPLACE THE TEMPORARY FLEX LINE THAT WAS INSTALLED ON THE L STEERING ACTUATOR. I ASSIGNED A MECH TO SEE WHICH LINE NEEDED TO BE REPLACED. THE MECH LOOKED UP THE PART AND FOUND OUT THERE WERE NO REPLACEMENT PARTS IN SUPPLY. I NOTIFIED ABCD ABOUT THE SIT. ABCD INSTRUCTED US TO HAVE IT REMOVED SO HE COULD BENCH CHK IT ON THE TEST STAND. THE LEAK CHK WAS OK SO HE SAID TO PUT IT BACK ON THE AIRPLANE AND SEE IF IT LEAKS AGAIN. THE MECH HOOKED UP THE LINE AND IT STARTED LEAKING AGAIN. THE MECH AND I WENT UP TO SEE ABCD IN THE MGR'S OFFICE TO FIND OUT WHAT HE WANTED DONE NEXT. ABCD SAID TO TAKE OUT THE LINE AND RESECURE EVERYTHING. THE MECH ACCOMPLISHED THE RESECURING, BUT I DID NOT GET TO SEE THE FINAL CLOSE UP. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR WAS CONTACTED AND REVEALED THE FOLLOWING DETAILS. THE NOSE GEAR COLLAPSE WAS A DIRECT RESULT OF THE FLEXIBLE HOSE INSTALLED IN THE L NOSE GEAR STEERING CYLINDER HYD CIRCUIT. THE FLEXIBLE HOSE PREVENTED THE NOSE GEAR DOWN AND LOCK LINKAGE FROM GOING OVER-CTR THUS PREVENTING A DOWN AND LOCKED CONDITION. THE RPTR BELIEVES THE FLEXIBLE HOSE INSTALLED AS AN INTERIM REPAIR FOR A LEAKING SOLID TUBE WAS TOO LONG AND COULD NOT BE CLAMPED ADEQUATELY. CALLBACK CONVERSATION WITH ACN 343596 RPTR REVEALED THE FOLLOWING: THE NOSE GEAR COLLAPSE WAS CAUSED BY THE FLEXIBLE NOSE STEERING LINE INTERFERING WITH THE DOWN LOCK MECHANISM. THIS FLEXIBLE HYD HOSE WAS INSTALLED AS AN INTERIM REPAIR FOR A LEAKING HARD LINE. THE RPTR STATES HE MADE THE FIRST INSTALLATION OF THE HOSE. ON THE OVERNIGHT LAYOVER THE LINE WAS REMOVED WITH THE HARD LINE TUBING FOR A BENCH CHK. THE LINE BENCH CHKED OK, BUT LEAKED AGAIN ON THE AIRPLANE AND THE INTERIM REPAIR FLEXIBLE HOSE WAS REINSTALLED.

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.

Attributes
ACN	343787
Time
Date	199608
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz
State Reference	US
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	DC-9 50
Operating Under FAR Part	Part 121
Flight Phase	landing other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	other personnel other
Qualification	other other : other
ASRS Report	343787
Person 2
Affiliation	company : air carrier
Function	other personnel other
Qualification	other other : other
ASRS Report	343596
Events
Anomaly	aircraft equipment problem : critical non adherence : published procedure other anomaly other
Independent Detector	other flight crewa other other : unspecified cockpit
Resolutory Action	none taken : unable
Consequence	other Other
Supplementary
Air Traffic Incident	other

A DC9-50 had the nose landing gear collapse on landing due to incorrect installation of interim repair hydraulic flex line interfering with down-lock mechanism.