A HELI PLT EXPERIENCES ENG FAILURE IN HIS MINI-500 WHILE HOVERING IN GND EFFECT AT 3-5 FT. HE LANDS HARD WITH DAMAGE TO THE SKIDS AND BLADES. NO INJURIES.

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I WAS IN A HOVER-TAXI IN A MINI-500 EXPERIMENTAL KIT HELI IN A SLIGHT R TURN AT 3-5 FT WITH A LIGHT R REAR QUARTERING TAILWIND WHEN THE ROTAX 582 ENG QUIT; I 'GUNNED' THE THROTTLE ONCE TO TRY AND RECOVER ENG RPM; HOWEVER; THE DECAY WAS RAPID IN ENG AND ROTOR RPM. I DID A HOVERING AUTOLAND LEVEL TOUCHDOWN. THE HELI BOUNCED UP SLIGHTLY AND CAME DOWN AGAIN ON THE L SKID WHICH COLLAPSED OUTWARD JUST BELOW THE XMEMBER ATTACH POINTS. THE HELI ROLLED ONTO ITS L SIDE; CUSHIONED BY THE 'FOLDING' L STRUTS. NO PLT INJURIES HOWEVER; ALL ROTOR BLADES DAMAGED BEYOND REPAIR. NO ONE UNDERSTANDS WHY THE STRUT DID NOT FOLD UNDERNEATH ME; OR SIMPLY 'SPREAD OUT' AND ABSORB THE SHOCK CONSIDERING THE LEVEL TOUCHDOWN AND/OR THE QUARTERING TAILWIND. DURING A SUBSEQUENT DISCUSSION WITH THE MANUFACTURERS' REPRESENTATIVE IN EXCELSIOR SPRINGS; MO; I FOUND OUT THAT A 'STRUT STIFFENER' KIT IS NOW AVAILABLE (BUT NOT NECESSARILY RECOMMENDED BY THE MANUFACTURER) TO PREVENT SUCH AN OCCURRENCE. I HAD AN EARLY KIT MODEL #6Y AND WAS UNAWARE OF SUCH AN AVAILABLE MODIFICATION. OTHERWISE; I WOULD HAVE SUFFERED NO DAMAGE! RECOMMEND ALL MINI-500 BUILDERS AVAIL THEMSELVES OF THE 'STRUT STIFFENER' KIT -- JUST IN CASE! ENG FAILURE CAUSE HAS YET TO BE DETERMINED.