COLLAPSE OF L MAIN GEAR.

Narrative

TOOK OFF FROM TEB FOR PLEASURE FLT. CONTACTED SWF FOR A TOUCH AND GO. GOT R MAIN NOT LOCKED DOWN INDICATION (NO R GREEN LIGHT) AND RED 'GEAR UNLOCKED' LIGHT ON. ABANDONED APCH; RECYCLED GEAR ONCE -- SAME INDICATIONS. RECYCLED AGAIN -- GOT ALL 3 GEAR DOWN AND LOCKED INDICATION. FLEW ACFT BACK TO TEB WITH ALL 3 GEARS DOWN AND LOCKED AS INDICATED. AT TEB; ON DOWNWIND; CHKED GEAR DOWN (3 GREEN). FINAL GEAR CHK STILL 3 GREEN. TOUCHED DOWN; LET NOSE DOWN; STARTED DECELERATION. AT APPROX 50- 60 KTS; GEAR UNSAFE HORN CAME ON; L MAIN GEAR COLLAPSED; THE ACFT SKIDDED; SWERVING L FOR APPROX 75-100 FT ONTO THE GRASS AND STOPPED. R MAIN AND NOSEWHEEL STAYED DOWN AND LOCKED. AT THIS POINT; I PULLED ALL ENG LEVERS AFT; SHUT OFF MASTER AND FUEL; AND EXITED THE ACFT. PUZZLING ELEMENTS -- FIRST; R MAIN SHOWING NOT DOWN AND LOCKED AT SWF. SECOND; L MAIN COLLAPSED AFTER ALL DOWN AND LOCKED INDICATION. TEMP WAS APPROX 20 DEGS F. PERSONALLY SUSPECT GEAR SELECTOR LEVER MALFUNCTION OR STRUT FAILURE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR WAS CALLED TO SEE IF ANYTHING HAD BEEN DETERMINED WHY THE L GEAR COLLAPSED. HE STATED THAT THIS TYPE OF FAILURE HAD HAPPENED BEFORE ON PIPER TWIN ACFT BUT HAD NO DEFINITE FACTS TO BACK UP THAT STATEMENT. ALTHOUGH EXACT CAUSE OF FAILURE HAS NOT BEEN DETERMINED; IT IS SUSPECTED THAT ENG EXHAUST AFFECTS A RUBBER GROMMET THAT HELPS TO ASSURE GEAR IS IN LOCKED POS. ACFT WAS PUT ON JACKS AND GEAR LOWERED. THE GEAR WENT TO LOCKED POS AS IT SHOULD. PROB IS; THE GEAR RETRACTED DURING ROLLOUT AT ABOUT 50-60 KTS. RPTR BELIEVES THE ACFT WILL BE TOTALED AS IT WAS AN OLDER MODEL OF THE NAVAJO. WITH THE GEAR COLLAPSE; THE PROP WAS BENT AND COMPLETE ENG TEARDOWN WILL HAVE TO BE ACCOMPLISHED. THAT WORK ALONE IS ESTIMATED TO BE WORTH MORE THAN MARKET VALUE OF ACFT.