RPTR CITES ACFT EQUIP DESIGN PROB AS CAUSE FOR ACFT DAMAGE WHEN NOSE GEAR COLLAPSED ON RWY.

Narrative

WHILE CONDUCTING FLT TEST PROGRAM IN MY NEWLY BUILT GLASAIR I-FT AND LNDG AT HERMISTON; THE NOSE GEAR FAILED AND THE NOSE OF THE AIRPLANE DROPPED TO THE RWY RESULTING IN A PROP STRIKE; SEPARATION OF THE NOSE GEAR FROM THE ACFT AND OTHER DAMAGE. PRIOR TO LNDG AT HERMISTON I HAD LANDED AT ANOTHER NEARBY PAVED ARPT AND ON ROLLOUT HAD HEARD A PAIR OF SNAPPING NOISES AND WHAT FELT LIKE WHEEL SHIMMY. HOWEVER; THE AIRPLANE TAXIED OKAY SO I RETURNED TO THE END OF THE RWY AND TOOK OFF. APPARENTLY; THE RUBBER BISCUIT ASSEMBLY HAD SEPARATED; ALLOWING THE NOSE GEAR TO DROP INTO A NEAR VERT POS. THE LNDG AT HERMISTON WAS A NORMAL SHORT-FIELD LNDG APCH AT 70-75 MPH (VSO IS 56 OR 57 MPH); WHICH IS MORE THAN 1.2 VSO. THE MAIN LNDG GEAR CONTACTED THE RWY JUST PAST THE NUMBERS. (WINDS WERE LIGHT AND VARIABLE). THE ACFT BALLOONED BACK INTO THE AIR 2 TO 3 FT AND CAME BACK DOWN ON THE MAIN GEAR WITH A VERY NOSE-HIGH ATTITUDE. THE NOSE BEGAN TO FALL WHEN I HEARD A LOUD BANG WHICH WAS THE NOSE GEAR CONTACTING THE RWY AND BREAKING OFF. OBVIOUSLY THE NOSE CONTINUED TO DROP TO THE PAVEMENT; RESULTING IN THE AFOREMENTIONED PROP STRIKE AND OTHER DAMAGE. EXAMINATION OF THE FAILED PARTS SHOWED: FAULTY DESIGN -- NO THROUGH BOLT. FAULTY EXECUTION OF THE DESIGN -- TACK-WELDS WHICH WERE 'COLD WELDS' (4 EACH) AND WHICH HAD BEEN GND OFF ALMOST COMPLETELY. THE PARTS HAD BEEN FURNISHED AS PART OF THE GLASAIR I-FT KIT. THE LNDG; IN MY OPINION; WAS NOT A PARTICULARLY HARD LNDG AND THERE WAS NO DAMAGE TO THE MAIN LNDG GEAR.