A FOKKER 100 RETURNED TO THE FIELD DUE UNABLE TO RETRACT THE LEFT MAIN LNDG GEAR CAUSED BY RETRACT ACTUATOR ROD END FAILURE.

Narrative

DECEMBER 2000; I INSTALLED THE LEFT MAIN LNDG GEAR RETRACT ACTUATOR ON ACFT PER JOB CARD INSTRUCTIONS. OCT 2001; ACFT ON TKOF EXPERIENCED A PROB WITH THE LEFT GEAR. WHEN THE F100 WAS BROUGHT BACK TO THE GATE IT WAS DETERMINED THE RETRACT ACTUATOR HAD SNAPPED AT THE ROD END. INITIAL INDICATIONS SHOW THAT THE ROD END WAS INSTALLED WITH THE GREASE FITTING IN THE DOWN POS INSTEAD OF THE UP POS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED AFTER THE ACTUATOR WAS REPLACED THE AIRPLANE HAD SEVERAL MONTHS IN SVC BEFORE THE ACTUATOR FAILED AGAIN. THE RPTR SAID THE FAILURE WAS AT THE ROD END WHERE IT IS SCREWED INTO THE GEAR RETRACT ACTUATOR PISTON. THE RPTR STATED THE THREADS ON THE ROD END AND PISTON END ARE VERY FINE AND NO PROTECTION IS MADE FOR WATER OR CORROSIVE FLUIDS FROM ENTERING AND CORRODING THE THREADS. THE RPTR SAID THIS IS THE THIRD TYPE OF FAILURE THE RPTR HAS WITNESSED WHERE THE ROD END FAILED. THE RPTR SAID IT WAS DETERMINED THE POS OF THE GREASE FITTING HAD NO BEARING ON THE FAILURE.