LNDG GEAR COLLAPSE.

Narrative

IN OCT 1988 I CONDUCTED A 135.293 .297 AND .299 CHECKRIDE ON COMM AND NEAR THE COMPLETION OF THE CHECKRIDE THE CROSSTUBE FAILED ON THE HELI DURING A SIMULATED SINGLE ENGINE LANDING. THE FLIGHT PORTION BEGAN NORMALLY AND WE WERE PERFORMING THE LAST INSTRUMENT APPROACH (ILS18) WHEN I SIMULATED A #2 ENGINE FAILURE AND HAD PLT FLY THE APPROACH SINGLE ENGINE. AT THE OUTER MARKER WE RECEIVED PERMISSION TO LAND ON THE RIGHT SIDE OF RWY 18 IN THE GRASS. THE SINGLE ENGINE APPROACH APPEARED NORMAL BUT ON TOUCHDOWN THE ACFT HAD A RAPID DECELERATION. I INITIATED UP COLLECTIVE AND BROUGHT THE #2 ENGINE BACK TO OPERATING RPM. NEAR THE END OF THE GND RUN OUT I FELT AN UNUSUAL SENSATION IN THE REAR CROSSTUBE AREA. I WAS UNSURE WHAT HAD OCCURRED SO I HAD PLT PICK THE ACFT UP TO A HOVER. WHEN EVERYTHING STABILIZED I ASKED PLT TO SET THE ACFT DOWN GENTLY SO I COULD GET OUT OF THE ACFT AND INSPECT THE LANDING GEAR. AS THE COLLECTIVE NEARED THE DOWNSTOP THE LANDING GEAR GAVE WAY; PLT AND I PULLED THE ACFT BACK TO A HOVER AND NOTIFIED TWR WE NEEDED TO REPOSITION TO PHI WITHOUT ADVISING THEM OF OUR MAINT PROBLEMS. THEY GAVE US PERMISSION TO REPOSITION TO PHI SO WE HOVER ON THE RIGHT SIDE OF RWY 18 BEHIND THE FIXED BASE OPERATORS NEAR THE AIRPORT BOUNDARY FENCE. WHEN WE GOT TO PHI WE CLIMBED OVER THE BOUNDARY FENCE; CROSSED A ROADWAY AND LANDED AT PHI AFTER A MECHANIC AND OTHER PILOTS PLACED PALLETS AND OLD TIRES ON THE HELI FOR US TO LAND ON. I SHUT THE ACFT DOWN WITHOUT FURTHER INCIDENTS. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: REPORTER STATES STRUCTURAL DAMAGE PROBABLY CAUSED BY PREVIOUS HARD LNDG SOMETIME BACK WHEN DOING SINGLE ENGINE PRACTICE. NO WAY TO DETECT BECAUSE ALL INTERNAL DAMAGE. STILL INVESTIGATING SITUATION.