A PA44-180 ON A TRAINING FLT PERFORMING TOUCH-AND-GO LNDGS; THE NOSE LNDG GEAR FAILED AFTER A FIRM LNDG. FOUND UPPER AND LOWER NOSE SCISSORS CONNECTION BOLT SHEARED.

Narrative

AFTER A NORMAL TRAINING FLT; MY STUDENT AND I WERE IN A R TFC PATTERN FOR RWY 12R. WE COMPLETED 2 TOUCH-AND-GOES NORMALLY; BUT ON THE THIRD LNDG; THE NOSE GEAR COLLAPSED AFTER A FIRM TOUCHDOWN ON THE MAINS. THOUGH THERE WAS SIGNIFICANT DAMAGE TO THE PROPS; THIS EVENT WAS CLASSIFIED AS AN INCIDENT. AFTER RESEARCHING THIS NOSE GEAR; I DISCOVERED THAT THERE WAS A SVC BULLETIN ISSUED IN 2005 FOR THE BOLT THAT CONNECTS THE UPPER AND LOWER DRAG LINKS. THIS SVC BULLETIN (PIPER SVC BULLETIN 1156) INDICATES THAT WITH MULTIPLE EXTENSIONS/RETRACTIONS; THIS BOLT CAN DEVELOP A WEAKNESS IN THE CTR OF THE BOLT. ON MY INCIDENT; THE BOLT WAS SHEARED MIDWAY ALONG THE BOLT. THERE WAS NO AIRWORTHINESS DIRECTIVE ASSOCIATED WITH THIS SVC BULLETIN THAT REQUIRES REPLACEMENT OF THE BOLT EVERY 500 HRS; AND I DISCOVERED IT HAD BEEN 984 HRS SINCE THE BOLT WAS REPLACED. ADDITIONALLY; THE TRAINING ENVIRONMENT REQUIRES SIGNIFICANTLY MORE GEAR CYCLES THAN THE AVERAGE NUMBER THAT WAS PROBABLY USED TO DETERMINE THE 500 HR REQUIREMENT. AN AIRWORTHINESS DIRECTIVE SHOULD BE ISSUED FOR THIS SVC BULLETIN AND THEY SHOULD RE-EXAMINE THE 500 HR NUMBER. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR BELIEVES THE FAILED SCISSORS BOLT CONTRIBUTED TO THE NOSE GEAR FAILURE. ACFT INCURRED DAMAGE TO THE PROP; ENG AND RELATED SHEET METAL.