MALFUNCTION GEAR WARNING SYS FAILS TO SOUND WARNING HORN WHEN LNDG GEAR PIN IS NOT IN THE PROPER LOCKED POS.

Narrative

AT APPROX PM45 HRS ON FEB/SAT/93; AFTER A NORMAL LNDG IN AN OLD MTR; I CLRED THE ACTIVE RWY; RECEIVED TAXI CLRNC FROM THE SANTA MONICA ARPT TWR; AND PROCEEDED TO TAXI WBOUND TO MY PARKING AREA. WHILE TAXIING; I NOTICED SOME SPECTATORS WAVING (BUT NOT SMILING) AND POINTING ENERGETICALLY AT MY ACFT; AND I IMMEDIATELY STOPPED. AT THAT MOMENT; I NOTICED THAT THE ACFT WAS TILTING SLIGHTLY TOWARDS A LOW R WING. MY FIRST THOUGHT WAS THAT I HAD A FLAT TIRE; BUT AS THE R WING CONTINUED TO SLOWLY SETTLE; I REALIZED THAT THE R LNDG GEAR WAS COLLAPSING. I IMMEDIATELY SHUT DOWN THE ENG; AND ALL ELECTRICAL SYS; AND LET THE ACFT SLOWLY SETTLE UNTIL THE R WING TIP CONTACTED THE GND. THIS PROC MINIMIZED ANY POSSIBLE DAMAGE TO THE ACFT. THERE WAS NO VISIBLE ACFT DAMAGE. IT WAS CLR THAT THE OSTENSIBLE CAUSE OF THE GEAR COLLAPSING WAS THAT THE LOCKING PIN ON THE R LNDG GEAR HAD FAILED TO MOVE INTO THE LOCK POS AFTER THE GEAR WAS LOWERED. THE GEAR THEN COLLAPSED SEVERAL MINS LATER AS THE HYD PRESSURE FADED. IT HAS NOT YET BEEN DETERMINED WHY THE LOCKING PIN FAILED TO MOVE INTO THE LOCKING POS AFTER THE GEAR WAS DOWN. IT WAS CLR THAT THE ACFT WAS BEING EXPOSED TO CONSIDERABLE STRUCTURAL STRESS WITH THE PARTIALLY COLLAPSED GEAR AND THE WING TIP CONTACTING THE GND; AND FURTHER IT WAS SERIOUSLY INTERFERING WITH ARPT FLT OPS BEING IN THE MIDDLE OF THE N TXWY. THE TWR ADVISED THAT THE ACFT COULD NOT BE MOVED UNTIL A SAFETY INSPECTOR FROM THE LAX FSDO HAD EXAMINED THE ACFT AND THE SCENE AND GIVEN HIS APPROVAL. AFTER AN HR ELAPSED WITHOUT THE FAA INSPECTOR APPEARING; THE MUSEUM OF FLYING MAINT CREW LIFTED THE ACFT WING UP AND LOCKED THE GEAR INTO POS; BUT DID NOT TOW THE ACFT CLR OF THE TXWY. ABOUT AN HR LATER; THE FAA INSPECTOR; MR. X; ARRIVED AT THE SCENE; AND AFTER ABOUT 1/2 HR OF EXAMINING THE ACFT GAVE HIS APPROVAL TO TOW THE ACFT TO THE NEARBY MAINT HANGAR OF THE MUSEUM OF FLYING. ONCE IN THE HANGAR; MR. X CHKED ALL OF MY LICENSES AND THOSE OF THE ACFT. HE CONTINUED EXAMINING THE ACFT; BOTH INSIDE THE COCKPIT AND OUTSIDE UNTIL IT GOT TOO DARK TO SEE MUCH. HE INSISTED THAT I MAKE A WRITTEN RPT; WHILE HE WATCHED; DESCRIBING ALL EVENTS FROM THE TIME I RECEIVED CLRNC TO LAND UNTIL THE ACFT WAS TOWED. HE FURTHER INSTRUCTED ME TO BE SURE TO INCLUDE ALL COMS WITH THE TWR AS I RECALLED THEM. I COMPLIED WITH HIS REQUEST; AND WAS TOLD THAT I WOULD RECEIVE A COPY OF THIS HANDWRITTEN (IN PENCIL) RPT WITHIN A WK FROM THE FAA. HE ASKED FOR MY BUSINESS AND HOME TELEPHONE NUMBERS SO THAT HE COULD CONTACT ME IF HE NEEDED ANY FURTHER INFO; AND DEPARTED. LATER THAT EVENING; MR. X CALLED ME AT HOME REQUESTING ADDITIONAL DATA ON THE ACFT SUCH AS THE TOTAL ACFT TIME; TOTAL ENG TIME; SERIAL NUMBER OF THE ENG; DATE OF LAST ANNUAL; ETC. I INFORMED HIM THAT THE ENG AND ACFT LOGS WERE IN THE ACFT AND NOT AT MY RESIDENCE; BUT THAT I WOULD OBTAIN THE INFO FOR HIM THE NEXT DAY WHICH I DID. I AM WRITING THIS NASA SAFETY RPT PRIMARILY BECAUSE OF THE INTIMIDATING AND THREATENING BEHAVIOR BY THE FAA INSPECTOR FAR BEYOND WHAT I BELIEVE IS APPROPRIATE TO THE ACTUAL CIRCUMSTANCES OF THE INCIDENT. THERE ARE NO LNDG GEAR WARNING LIGHTS IN THE COCKPIT OF THE MTR ALTHOUGH LATER MODELS DO HAVE SUCH LIGHTS. THERE IS A WARNING HORN WHICH SOUNDS IF THE THROTTLE IS COMPLETELY CLOSED. THE WARNING HORN IS ALSO EFFECTIVE IF IT IS ACTUATED; AND IF IT CAN BE HEARD. HOWEVER; IN CURRENT GA OPS; PRACTICALLY ALL APCHS ARE PWR-ON APCHS TO WHEEL LNDGS; AND THE THROTTLE IS NEVER RETARDED SUFFICIENTLY TO PERMIT THE HORN TO BLOW INDICATING AN UNLOCKED GEAR UNTIL AFTER TOUCHDOWN WHEN THE THROTTLE IS CLOSED COMPLETELY. BY THEN IT'S PROBABLY TOO LATE TO DO ANYTHING; AND A HIGH SPD GND LOOP IS LIKELY RESULTING IN EXTENSIVE ACFT DAMAGE. SINCE MY INCIDENT THE OTHER DAY; I HAVE TALKED TO 2 OTHER MTR PLT/OWNERS WHO HAVE HAD THAT EXPERIENCE. ONE OF THESE PLTS; WHO HAD ONE OF HIS GEAR COLLAPSE JUST AFTER HE CUT THE THROTTLE ON TOUCHDOWN OF A WHEEL LNDG; CLAIMED HE NEVER HEARD THE HORN (WHICH WAS SUBSEQUENTLY SHOWN TOBE OK); BECAUSE HE HAD RECENTLY INSTALLED A NEW AUTOMATIC NOISE ATTENUATING HEADSET WHICH MADE IT IMPOSSIBLE FOR HIM TO HEAR THE HORN IF THE CANOPY WAS COMPLETELY OPEN...MAYBE? TO SUM UP; MY LNDG PROCS IN THE FUTURE WILL CERTAINLY INCLUDE A FULL RETARDATION OF THE THROTTLE ON THE DOWNWIND LEG TO INITIATE THE WARNING HORN PRIOR TO LOWERING THE LNDG GEAR. AND DURING MY NEXT ANNUAL; I WILL ADD GEAR WARNING LIGHTS TO MY INST PANEL AS THEY EXIST ON LATER MODELS OF THE MTR.