AIR CARGO OP HAS ACFT DAMAGE ON ROLLOUT DUE TO POOR RWY CONDITION.

Narrative

ROCK DAMAGE OCCURRED TO BELLY OF ACFT DURING LNDG ROLL. WINDS ESTIMATED 050 DEGS AT 5 KTS. LNDG RWY 16; RWY COMPOSITION: DIRT AND ROCKS; TOUCHDOWN ZONE HARD PACKED; TURN-AROUND/PARKING: HARD PACKED; CTR OF RWY RUTTED FROM PREVIOUS LNDGS FROM VARIETY OF ACFT. RWY WAS DRY AND POWDERY IN SPOTS. TOUCHDOWN WAS UNEVENTFUL. DURING ROLLOUT STARTING APPROX 400 YARDS FROM TOUCHDOWN; MAIN TIRES SANK INTO RWY APPROX 12-15 INCHES FOR A DISTANCE OF APPROX 200 YARDS. NOTHING ABNORMAL WAS NOTICED AT THIS TIME. POST-FLT INSPECTION REVEALED A GASH APPROX 3 FT FROM SIDE TO SIDE JUST FORWARD OF THE TAILSKID AND A HOLE TO THE L OF THE TAILSKID. HOLE SIZE APPROX 12 INCHES X 15 INCHES. FURTHER INSPECTION REVEALED NUMEROUS SCRAPES; SOME CREASES; AND AT LEAST ONE MORE SMALL (SILVER-DOLLAR SIZE) HOLE FORWARD OF THE MAIN GEAR; APPROX CTR OF THE FUSELAGE. THERE WAS NO DAMAGE TO THE TAILSKID OR ANY BUCKLING ASSOCIATED WITH A TAILSTRIKE (A FLOOR PANEL WAS REMOVED BY MAINT TO CHK EXTENT OF VISIBLE DAMAGE). RUT DEPTH WAS DETERMINED WHEN PLT; FO; AND FE WALKED ENTIRE LENGTH OF RWY TO TRY TO DETERMINE LOCATION WHERE DAMAGE OCCURRED. ACFT WT ON LNDG WAS 134000 LBS; MAX ALLOWABLE LNDG WT FOR THIS RWY (135000 LBS) WAS DETERMINED FROM FAA APPROVED RWY ANALYSIS FOR 80 PERCENT DATA. MINING COMPANY WORKERS USED GRADERS; WATERING TRUCKS; AND TAMPING MACHINES TO NORMALLY KEEP THE RWY IN GOOD CONDITION. NECESSARY EQUIP WAS AT A REMOTE PART OF THE MINING OP AND APPARENTLY HAD NOT WORKED THE RWY FOR SEVERAL DAYS. ALSO; RECENT WX HAD BEEN RAIN FREE; ALLOWING THE NORMALLY COMPACT DIRT TO DRY OUT. FOR RWYS OF THIS NATURE; SUPVRS NEED TO ENSURE THE RWY IS USABLE FOR HVY-LIFT OPS OF THIS NATURE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THEY HAVE FLOWN INTO THIS ARPT MANY TIMES; BUT ON THIS DATE THE RWY PROBS WERE REALLY BAD. THIS ARPT IS OPERATED BY A GOLD MINING COMPANY AND THEY WERE SETTING UP A NEW MINE SO THE EQUIP WAS ON THE OTHER SIDE OF THE MOUNTAIN AND UNABLE TO KEEP THE RWY IN CONDITION AS THEY USUALLY DO. RPTR'S CHIEF PLT RECOMMENDED THAT HE FILE HIS RPT BECAUSE THE COST OF DAMAGE SEEMED LIKE IT MIGHT BE HIGH ENOUGH THAT THE FAA MIGHT BECOME INVOLVED. THE ARPT IS NOT ON CHARTS AND SO THE STATE HAS NO RESPONSIBILITY FOR ITS MAINT.