THE PLT RPRTD THAT AS HE 'HOVERED' THE HELICOPTER BTN 5 & 10 FT AFTER LIFT-OFF, HE NOTED A 'SLIGHT LATERAL VIBRATION.' HE LNDD IMMEDIATELY, BUT THE VIBRATION/GROUND RESONANCE (VIB) INCREASED IN SEVERITY, SO HE 'SHUT-OFF' BOTH THROTTLES. THE VIB CONTD TO THE EXTENT THAT HE COULDN'T HOLD ONTO THE CYCLIC CTL STICK. THE TRANSMISSION SEPD FM ITS ATTACH POINT &THE MAIN ROTOR BLADES CONTACTED THE GND BFR THE ENG STOPPED. AN EXAM REVEALED THE TRANSMISSION SUPPORT BARS (TSB'S) HAD FAILED DRG THE ACDNT. THERE WAS EVIDENCE OF OVERLOAD FAILURE OF THE TSB'S, EXCEPT THE LEFT FWD TSB HAD EVIDENCE OF FA- TIGUE ON EITHER SIDE OF THE BUCKLED AREA. A STRIATION COUNT INDCD THE CRACK HAD PROGRESSED OVR AN ESTD TIME OF AT LEAST 1 HR & 15 MIN. ALSO, AN ARM OF THE STARFLEX ASSY (S/A) HAD FAILED. THE S/A HAD 323 HRS SINCE RPLCMNT. CRAZE CRACKS WERE FND ON THE S/A, BUT AN EXAM FAILED TO VERIFY WHETHER THEY HAD FORMED BFR OR DRG THE ACDNT. THE S/A WAS APRX 3% POROUS & HOLES IN THE ENAMEL BARRIER ALLOWED ENVIRONMENTAL BLACKENING OF ITS EDGES. LNDG SKID SHOCK ABSORBERS WERE BADLY DMG.