PRECISION LLC

DURING INSPECTION AT AFTT: 21628.9, A CRACK WAS FOUND ON THE RH TITANIUM DECK, ON THE FRONT AREA OF THE FORWARD SEATING PLANE OF THE MGB FLEXIBLE MOUNTING PLATE. THE MANUFACTURER ISSUED AN ENGINEERING REPORT ALLOWING CONTINUED OPERATION FOR UP TO 500HRS WITH CLOSE MONITORING OF THE DEFECT AREA. DURING A SUBSEQUENT FERRY FLIGHT WITH MULTIPLE STOPS, THE ENGINEER ONBOARD NOTED THAT SUBJECT CRACK HAD APPEARED TO GROW IN LENGTH AND THE AIRCRAFT MADE A PRECAUTIONARY LANDING AT THE NEAREST AIRPORT. ONCE ON THE GROUND AN ADDITIONAL CRACK WAS DISCOVERED ORIGINATING AT A RIVET ADJACENT TO THE ORIGINAL CRACK AND MOVING IN A PARALLEL DIRECTION. THE SECOND DEFECT IS BEYOND THE SCOPE OF APPROVAL FOR CONTINUED OPERATION IN ACCORDANCE WITH THE ENGINEERING REPORT. THE FERRY FLIGHT WAS DISCONTINUED AT THAT TIME.

BOTH TRANSFORMER RECTIFIERS (TRUS) WENT OFFLINE (CIRCUIT BREAKERS POPPED) DURING AN AERIAL FIREFIGHTING MISSION. THIS ACTIVATED THE EMERGENCY ELECTRICAL SYSTEM AND THE PILOTS WERE ABLE TO RETURN TO THE POINT OF DEPARTURE WITHOUT FURTHER INCIDENT. UPON INSPECTION ON THE GROUND, IT WAS DETERMINED THAT WIRING AT THE TRU ELECTRICAL CONNECTOR HAD BEEN PINCHED/CHAFFED BY SURROUNDING STRUCTURE CAUSING THE ARC AND OVERCURRENT. BOTH TRUS AND ASSOCIATED WIRING WERE DAMAGED AS A RESULT OF THE INCIDENT. EACH TRU IS MOUNTED ON A REMOVABLE HINGE-HALF, IT IS BELIEVED TO HAVE BEEN INSTALLED IN THE MATING HINGE-HALF ONCE TOOTH FARTHER AFT, CAUSING CONTACT WITH THE SURROUNDING STRUCTURE.

THE NO. 1 TR DRIVESHAFT BEARING SLEEVE BECAME DISPLACED FROM THE NO.1 TR DRIVESHAFT BEARING ASSEMBLY. THIS CAUSED A GAP BETWEEN THE TR DRIVESHAFT AND THE BEARING INNER RACE. DURING AIRCRAFT SHUTDOWN, THE DRIVESHAFT AND BEARING INNER RACE WERE MAKING CONTACT CAUSING NOISE AND VIBRATION FOR THE PILOT AND ON-SITE MECHANIC TO REMOVE THE COWLINGS AND INVESTIGATE FURTHER. ONCE EXPOSED, SIGNIFICANT WEAR WAS OBSERVED ON THE TAIL ROTOR DRIVESHAFT AT THE LOCATION OF THE NO. 1 BEARING.

THE NO. 1 TR DRIVESHAFT BEARING SLEEVE BECAME DISPLACED FROM THE NO. 1 TR DRIVESHAFT BEARING ASSEMBLY. THIS CAUSED A GAP BETWEEN THE TR DRIVESHAFT AND THE BEARING INNER RACE. DURING AIRCRAFT SHUTDOWN, THE DRIVESHAFT AND BEARING INNER RACE WERE MAKING CONTACT CAUSING NOISE AND VIBRATION. THIS WAS CAUSE FOR THE PILOT AND ON-SITE MECHANIC TO REMOVE THE COWLINGS AND INVESTIGATE FURTHER. ONCE EXPOSED, SIGNIFICANT WEAR WAS OBSERVED ON THE TAIL ROTOR DRIVESHAFT AT THE LOCATION OF THE NO. 1 BEARING.

DURING A GROUND RUN IN PREPARATION FOR A FERRY FLIGHT, THE PILOT FELT A SIGNIFICANT VIBRATION IN THE AIRFRAME ACCOMPANIED BY AN ABNORMAL NOISE AND MGB CHIP CAUTION LIGHT. THE PILOT PERFORMED A NORMAL ENGINE SHUTDOWN AND INFORMED MAINTENANCE PERSONNEL. UPON REMOVAL AND DISASSEMBLY OF THE BEVEL REDUCTION GEARBOX AND EPICYCLIC REDUCTION GEARBOX, A SINGLE CRUSHED TOOTH WAS NOTED ON THE RING GEAR ALONG WITH A SIGNIFICANT AMOUNT OF METALLIC FLAKES WITHIN THE SYSTEM.

A TECHNICIAN REPORTED THAT DURING HIS DAILY INSPECTION HE FELT SOME "LOOSENESS" IN THE SWASHPLATE THAT HE HAD NOT NOTICED ON PRIOR DAILY INSPECTIONS. HE INVESTIGATED FURTHER AND FOUND THAT THE SWASHPLATE INNER RING WAS CRACKED AT THE GIMBAL ATTACHMENT LUG. THE AIRCRAFT WAS IMMEDIATELY GROUNDED.

A TECHNICIAN REPORTED THAT DURING HIS DAILY INSPECTION HE FELT SOME "LOOSENESS" IN THE SWASHPLATE THAT HE HAD NOT NOTICE ON PRIOR DAILY INSPECTIONS. HE INVESTIGATED FURTHER AND FOUND THAT THE SWASHPLATE INNER RING WAS CRACKED AT THE GIMBAL ATTACHMENT LUG. THE AIRCRAFT WAS IMMEDIATELY GROUNDED.

ENGINE WAS REMOVED FOR O/H, THE ENGINE MOUNT WAS INSPECTED AND REJECTED DUE TO CRACKS.

DURING INSPECTION, FOUND RT LG TUNNEL CRACKED, STATION 125, WL 21, RBL 13.5 & LBL 13.5, UPON FURTHER INSPECTION A CRACK IN THE SAME LOCATION WAS FOUND ON THE LT SIDE AS WELL. STOP DRILLED & FABRICATED REPAIR PARTS FROM NEW PART & INSTALLED IAW SRM 1 CHAPTER 5 2 1 AS APPLICABLE.

DURING INSPECTION, RT LG TUNNEL SUPPORT FOUND TO BE CRACKED.

DURING INSPECTION, STIFFENER FOUND TO BE CRACKED NEAR TAIL BOOM ATTACH INSPECTION PANEL.

DURING INSPECTION, STIFFENER NEAR TAIL BOOM ATTACH INSPECTION PANEL FOUND TO BE CRACKED.

A CRACK APPROXIMATELY 170 MM LONG WAS FOUND ON THE LEADING EDGE, AFT OF FWD MOUNT POINT. (K)