A TB-20 TRINIDAD LANDED WITH ITS NOSE GEAR NOT DOWN.

Narrative

WHILE APCHING THE TFC PATTERN AT KEY WEST INTL ARPT; I ATTEMPTED TO LOWER THE LNDG GEAR. WHEN THE GEAR SWITCH WAS PUT DOWN; ALL LIGHTED DISPLAYS ON THE INST PANEL WENT DARK; AS IF THE ELECTRICAL SYS WAS SHORT-CIRCUITED. THE GEAR FAILED TO GO DOWN AND LOCK; AS INDICATED BY THE LACK OF ANY GREEN GEAR LIGHTS. I REQUESTED PERMISSION FROM THE TWR TO DEPART THE PATTERN AND ORBIT OUTSIDE THE ATA. I CIRCLED FOR AN HR ATTEMPTING TO LOWER THE GEAR; FOLLOWING PROCS IN THE PLT OPERATING HANDBOOK; PULLING THE GEAR CIRCUIT BREAKER; RESETTING IT; AND OPERATING THE GEAR SWITCH ABOUT 15 TIMES. THERE WAS NO RESPONSE OTHER THAN A SHORTING OF THE ELECTRICAL SYS WHEN THE GEAR SWITCH WAS PUT DOWN. I THEN ATTEMPTED TO LOWER THE GEAR BY THE EMER BACKUP SYS. I FOLLOWED THE CHKLIST; PULLING THE GEAR CIRCUIT BREAKER; APPLYING FLAPS AND SLOWING THE AIRPLANE TO RECOMMENDED SPD. THE 2 MAIN WHEELS INDICATED DOWN AND LOCKED BY 2 GREEN LIGHTS. THE NOSE GEAR DID NOT INDICATE DOWN. I REQUESTED PERMISSION TO FLY-BY FOR VISUAL INSPECTION; AND THE TWR RPTED THAT THE NOSEWHEEL APPEARED NOT COMPLETELY DOWN AND LOCKED. I ATTEMPTED TO SHAKE THE GEAR DOWN BY MANEUVERING; BUT TO NO AVAIL. AFTER BEING CLRED TO LAND; I ROLLED THE MAIN WHEELS ON; SLOWED THE AIRPLANE AND ALLOWED THE NOSE TO SETTLE. THE NOSEWHEEL HAD FAILED TO LOCK AND THE NOSE SETTLED ONTO THE RWY; DAMAGING THE PROP AND LOWER COWL. THE PROB APPEARS TO HAVE BEEN CAUSED BY A MALFUNCTION IN BOTH THE LNDG GEAR PWR PACK AND THE EMER EXTENSION SYS. THE PWR PACK HAD BEEN OVERHAULED 2 MONTHS EARLIER. I BELIEVE THESE SYS SHOULD BE REVIEWED BY THE AIRFRAME MAKER; AND APPROPRIATE CAUTIONS OR REMEDIAL ACTION TAKEN. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: THE OWNER PLT OF THIS ACFT IS 'AN ELECTRONICS AND AVIONICS TYPE MECH. THE ACFT IS A TB-20 TRINIDAD BUILT BY AEROSPATIALE. THE LNDG GEAR IS RAISED AND HELD IN THE UP POS BY A HYD SYS THAT IS ELECTRICALLY DRIVEN. WHEN THE GEAR IS UP; LIMIT SWITCHES TURN OFF THE ELECTRICAL PUMP. THE RPTR BELIEVES THAT THE SWITCHES WERE OUT OF ADJUSTMENT CAUSING THE PUMP TO TRY TO LIFT THE GEAR WHEN IT WAS ALREADY UP. THE MAIN GEAR; IN THE EMER OP; FREEFALLS AND IS PUSHED DOWN BY THE WIND. THE NOSE GEAR FALLS FORWARD INTO THE WIND. IT IS ASSISTED BY 2 'GAS RODS.' AT EACH 100 HR INSPECTION; ONE OF THE GAS RODS MUST BE DISCONNECTED AND THE OTHER MUST BE ABLE TO LOCK THE NOSE GEAR IN PLACE. THE RPTR BELIEVES THAT THE GAS RODS HAVE FINALLY WORN OUT AFTER 10 YRS OF FLT. THIS SUPPOSITION IS BACKED BY HAVING TO REPLACE THE GAS RODS THAT ASSIST IN OPENING THE GULL WING PAX ENTRANCE DOORS. A SVC BULLETIN REGARDING THE EMER LNDG GEAR OP HAS BEEN ISSUED AND COMPLIED WITH. THE LCL FSDO IS AWARE OF THIS INCIDENT. THE RPTR IS NOW AWARE OF THE FAA AVIATION SAFETY HOT LINE.