MOONEY M20 GEAR FOLDED DURING LNDG ROLL DUE TO THE MANUAL GEAR ACTUATING BAR SLIPPING OUT OF ITS EXTEND POS DETENT.

Narrative

DURING APCH TO AN UNCTLED RWY IN VMC CONDITIONS; I PERFORMED A BEFORE LNDG CHKLIST. THIS INCLUDED ROTATING THE MANUAL GEAR HANDLE TO THE 'UP' POS AND LOCKING IT INTO PLACE; THEREFORE PLACING THE GEAR DOWN. ON FINAL; BOTH MY PAX (ALSO A COMMERCIALLY-CERTIFIED PLT) AND I CONFIRMED THE SECURITY OF THE GEAR HANDLE BAR AND THE ASSOCIATED GREEN LIGHT INDICATION ON THE INST PANEL THAT INDICATED A SAFE GEAR DOWN CONDITION. WE CONTINUED THE APCH TO THE ROUND OUT AND FLARE AND EXECUTED A SMOOTH LNDG. WE ROLLED FOR APPROX 200-300 FT UNEVENTFULLY. I THEN HEARD A MUFFLED THUMP; ACCOMPANIED BY THE ACFT CONTINUING TO SETTLE TO THE RWY. THE PROP STRUCK THE GND AND THE ENG ENCOUNTERED A SUDDEN STOPPAGE. THE ACFT SLID ON THE CTRLINE FOR AN ADDITIONAL 1000 FT AND WE EGRESSED UNEVENTFULLY. AFTER SHUTDOWN; POSTFLT INSPECTION REVEALED THE MANUAL GEAR EXTENSION HANDLEBAR HAD POPPED OUT OF ITS DETENT AND HAD MOVED APPROX 3/4 OF ITS ROTATION TOWARD THE GEAR 'UP' POS. THE ACFT WAS ABLE TO BE JACKED UP TO EXTEND ITS GEAR AND WAS TOWED TO PARKING. THE ACFT DID NOT SUSTAIN SUBSTANTIAL DAMAGE AND WAS CONSIDERED AN INCIDENT.