N316PA

Part: RIB — CRACKED (LT WING) · airframe 7,321 hrs

DURING A ROUTINE INSPECTION, A NOSE RIB IN THE LEFT WING WAS FOUND TO BE CRACKED. RIB IN QUESTION IS LOCATED AT WING STA 50.05; CRACKING WAS SEEN WHERE RIB ADJOINS WING SPAR, DIRECTLY NEXT TO ELECTRIC FUEL PUMP. CRACKING OCCURRED AT RIVET HOLES. IT IS SUSPECTED THAT CRACKING IS CAUSED BY LOADS ON LANDING GEAR TRANSFERRING TO SURROUNDING STRUCTURE, INCLUDING THIS RIB.

Part: RIB — CRACKED (RT WING) · airframe 7,321 hrs

DURING A ROUTINE INSPECTION, A NOSE RIB IN THE RIGHT WING WAS FOUND TO BE CRACKED. RIB IN QUESTION IS LOCATED AT WING STA 50.05; CRACKING WAS SEEN WHERE RIB ADJOINS WING SPAR, DIRECTLY NEXT TO ELECTRIC FUEL PUMP. CRACKING OCCURRED AT RIVET HOLES. IT IS SUSPECTED THAT CRACKING IS CAUSED BY LOADS ON LANDING GEAR TRANSFERRING TO SURROUNDING STRUCTURE, INCLUDING THIS RIB.

Part: SKIN — CRACKED (RT WING) · airframe 7,321 hrs

DURING A ROUTINE INSPECTION, THE RIGHT WING SKIN AROUND FUEL TANK VENT PANEL WAS FOUND CRACKED. CRACK WAS APPROX 1.5 INCHES AND EXTENDED FWD OF THE PANEL. THE PANEL AND DOUBLER WERE NOT DAMAGED. THIS AREA HAS A HISTORY OF SEMI-FREQUENT CRACKING ON THIS AIRCRAFT TYPE AND IS ADDRESSED IN SB 1287.

Part: DOWNLOCK SWITCH — FALSE INDICATION (MLG) · airframe 7,067 hrs

THE PILOT NOTED THAT THE RIGHT GEAR DOWN-AND-LOCKED INDICATION WAS INTERMITTANT. IT WOULD FLICKER OR WOULD FAIL TO INDICATE DOWN. AFTER AN UNEVENTFUL LANDING, THE RIGHT GEAR WAS INSPECTED AND IT WAS DISCOVERED A WIRE IN THE DOWN LIMIT SWITCH HAD BROKEN. THIS REPAIR STATION HAS DOCUMENTED NUMEROUS PROBLEMS WITH THIS PART (SEE OTHER SDRS FOR THIS PART FOR HISTORY). THE MANUFACTURER HAS RE-DESIGNED THE SWITCH, HOWEVER THE REVISED PART (REV N?) APPEARS TO BE DIFFICULT TO OBTAIN, WHEREAS THE PROBLEMATIC EARLIER DESIGNS ARE MORE EASILY OBTAINED. THE SWITCH THAT FAILED IN THIS REPORT WAS REV M AND HAD BEEN INSTALLED LESS THAN ONE YEAR.

Part: SNAP RING — BROKEN (TACH SHAFT) · airframe 6,932 hrs

THE ENGINE OIL SCREENS WERE REMOVED AND INSPECTED FOR DEBRIS. THE LEFT ENGINE OIL SCREEN CONTAINED A SNAP RING THAT WAS BROKEN IN THREE PIECES. THE ENGINE WAS REMOVED AND SENT TO ANOTHER REPAIR STATION FOR OVERHAUL. THE STATION REPORTED THAT THE SNAP RING CAME FROM THE END OF THE TACHOMETER SHAFT, WHICH IS CONNECTED TO THE END OF THE CAM AND SITS IN THE ACCESSORY HOUSING. THE SNAP RING BROKE AND MIGRATED OUT OF PLACE AND INTO THE OIL SUMP.

Part: DOWNLOCK SWITCH — SEPARATED (MLG) · airframe 6,756 hrs

WHILE PERFORMING A GEAR FUNCTIONAL TEST, NOTED THAT THE RT GEAR DOWNLOCK SWITCH FAILED TO ACTIVATE THE GEAR PUMP WHEN THE DOWNLOCK WAS UNSEATED. CLOSE INSPECTION REVEALED 2 BROKEN WIRES AT THE SWITCH BODY; THE SWITCH HAD BEEN IN SERVICE 2 WEEKS AND HAD ACCRUED 45 HOURS. THE PN 89291-003, SWITCH IS REVISION M, INCORPORATING LONGER SHRINK WRAP ON THE HARNESS TO PREVENT FATIGUE FAILURE OF THE WIRES. MFG HAS SINCE REVISED THE PART DESIGN TO REV N BECAUSE THEY DISCOVERED THE REV M SHRINK WRAP LENGTH WAS STILL NOT ADEQUATE TO PREVENT THE FATIGUING OF THE WIRES.

Part: BULKHEAD — CRACKED (NOT REPORTED) · airframe 6,405 hrs

DURING A ROUTINE INSPECTION, CRACKS WERE NOTED IN A BULKHEAD IN THE AFT UPPER FUSELAGE ADJACENT TO THE DORSAL FIN FORWARD ATTACH FITTING. THE CRACKS WERE MADE VISIBLE BY REMOVAL OF THE FAIRING THAT COVERS THE FORWARD ATTACH FITTING. FURTHER INSPECTION OF THE BULKHEAD AFTER IT WAS REMOVED REVEALED IT WAS CRACKED IN TWO PLACES- THE OUTBOARDMOST RIVET HOLES, LEFT AND RIGHT, THAT ATTACH IT TO THE P/N 78965-007 DOUBLER. CRACKS RADIATED OUTWARD FROM EACH RIVET HOLE AND A CRACK WAS SEEN IN THE INNER RADIUS OF THE FLANGE AT THE BULKHEAD'S TOP. NO CORROSION WAS PRESENT ON THE BULKHEAD OR ANY ADJACENT PARTS. IT IS SUSPECTED THAT INFLIGHT STRESSES IMPOSED ON THE DORSAL FIN TRANSFERRED TO THE BULKHEAD AND INSTIGATED THE CRACKING.

Part: DOUBLER — CRACKED (BULKHEAD) · airframe 6,405 hrs

THE AFT FUSELAGE BULKHEAD, HAD BEEN FOUND CRACKED AND WAS IN THE PROCESS OF BEING REPLACED. WHEN THE BULKHEAD WAS REMOVED, THE DOUBLER, SUBJECT OF THIS REPORT, WAS FOUND TO HAVE NUMEROUS CRACKS AS WELL. CRACKS WERE CONCENTRATED IN THE 2 OTBD TOP RIVET HOLES, SAME AS THE BULKHEAD IT WAS RIVETED TO, AND HAD MULTIPLE CRACKS IN EACH LOCATION. NO CORROSION WAS PRESENT. IT IS SUSPECTED IN FLIGHT LOADS IMPOSED ON THE DORSAL FIN INSTIGATED THE CRACKING IN THE BULKHEAD AND DOUBLER.

Part: ANGLE — CRACKED (ZONE 600) · airframe 6,258 hrs

DURING A PROGRESSIVE INSPECTION, AN ANGLE IN THE RT WING WAS FOUND TO BE CRACKED BEHIND THE LANDING GEAR SIDE BRACE FITTING. THE CRACKED ANGLE HAD BEEN INSTALLED IAW SB 1161 AND WAS CONTAINED IN KIT PN 767-398.

Part: ANGLE — CRACKED (ZONE 500) · airframe 6,258 hrs

DURING A PROGRESSIVE INSPECTION, AN ANGLE IN THE LT WING WAS FOUND TO BE CRACKED BEHIND THE LANDING GEAR SIDE BRACE FITTING. THE CRACKED ANGLE HAD BEEN INSTALLED IAW SB 1161 AND WAS CONTAINED IN KIT, PN 767-397.

Part: WIRE — DETACHED (DOWNLOCK SWITCH) · airframe 5,818 hrs

THE RT MAIN GEAR DOWN-AND-LOCK LIGHT DID NOT ILLUMINATE. THE IP ACTIONED RELEVANT CHECKLIST BUT IT FAILED TO RESOLVE THE ISSUE. DIVERTED TO A TOWERED AIRPORT AND PERFORMED A FLYBY OF THE TOWER BEFORE PERFORMING AN UNEVENTFUL LANDING. INSPECTION OF THE LANDING GEAR REVEALED THE RT MAIN DOWNLOCK SWITCH HAD ONE WIRE THAT DOES NOT APPEAR TO HAVE BEEN PROPERLY CRIMPED INTO THE SWITCH AND WAS HELD IN PLACE BY ONLY SILICONE. THE SWITCH HAD BEEN INSTALLED TO REPLACE ANOTHER FAILED SWITCH- REF SDR FQAR20140402032. THE SWITCH UNDERWENT 305 LANDINGS SINCE INSTALL.

Part: DOWNLOCK SWITCH — BROKEN (RT MLG)

DURING FINAL APPROACH, PILOT LOWERED LANDING GEAR AND RECEIVED NO DOWN AND LOCKED INDICATION ON THE RT GEAR. THIS WAS AFTER 2 SUCCESSFUL TOUCH AND GO MANEUVERS. THE PILOT NOTIFIED TOWER OF THE CONDITION. THE TOWER THEN VERIFIED THAT THE LANDING GEAR WAS DOWN BY VISUAL OBSERVATION. AFTER THE ACFT MADE A SUCCESSFUL LANDING IT WAS BROUGHT IN THE MAINTENANCE FACILITY FOR INSPECTION. UPON INSPECTION BY A MECHANIC, IT WAS DISCOVERED THAT THE DOWNLOCK SWITCH HAD A BROKEN WIRE ON THE SWITCH ASSY. THE WIRES OF THIS SWITCH ARE ENCASED IN SHRINK WRAP FROM THE MOLEX CONNECTOR TO APPROX 1.5" FROM THE SWITCH BODY, WHICH APPEARS TO ENCOURAGE THE WIRES TO FLEX IMMEDIATELY OUTSIDE THE SWITCH BODY DURING THE MOVEMENT OF THE GEAR. THIS REPAIR STATION HAS SEEN AND REPORTED A NUMBER OF SWITCH FAILURES THAT ARE SIMILAR AND HAVE CAUSED INCORRECT GEAR INDICATIONS. THE SWITCH HAD BEEN INSTALLED 2 MONTHS PRIOR.

Part: DOWNLOCK SWITCH — SEPARATED (MLG)

DURING THE LANDING GEAR FUNCTIONAL TEST, CALLED OUT IN THE PA-44 MM, MAINTENANCE DISCOVERED WHEN THE RT MAIN LANDING GEAR (RMLG) DOWNLOCK HOOK WAS UNSEATED, UNLOCKED, THE GEAR PUMP WOULD FAIL TO OPERATE. THE TECHNICIANS VISUALLY INSPECTED THE RMLG DOWNLOCK SWITCH AND FOUND NO DEFECTS, BUT THE SWITCH REMAINED INOPERATIVE. THE DOWNLOCK SWITCH WAS REPLACED. THE FAULTY SWITCH WAS EXAMINED CLOSELY AFTER REMOVAL, AND THEN IT WAS DISCOVERED THAT ONE WIRE WAS BROKEN INSIDE THE INSULATION. THIS WAS ONLY REVEALED WHEN THE WIRE WAS SEPARATED FROM THE BUNDLE AND GENTLY TUGGED. THE SWITCHES HAVE A WIRING HARNESS COVERED IN THICK SHRINK WRAP THAT ENCOURAGES THE WIRES TO FLEX IN ONE SMALL AREA NEAR THE SWITCH BODY. THE SHRINK WRAP AND SILICONE ON THE WIRES ALSO MAKE IT EXTREMELY DIFFICULT TO SEE ANY DAMAGE OR DEFECTS WITH THE WIRES, SO EVEN DILIGENT INSPECTION MAY NOT DETECT A BROKEN WIRE.

Part: ANGLE — CRACKED (LT NACELLE)

DURING A SCHEDULED INSPECTION, A CRACK WAS FOUND IN THE NACELLE ANGLE. UPON FURTHER INVESTIGATION, IT WAS FOUND THAT THE CRACK WAS BETWEEN THE 2 RIVETS THAT EXTENDED THRU THE WING SKIN INTO CAP (P/N 67097-002 OR -003 DEPENDENT ON SIDE) WHICH IS ATTACHED TO A WEB (PN 67079-000 OR 001 DEPENDENT ON SIDE) THAT THE MAIN GEAR AFT ATTACH POINT IS MOUNTED. IT IS SUSPECTED THAT THIS IS A FAILURE DUE TO FATIGUE.

Part: ANGLE — CRACKED (RT NACELLE)

DURING A SCHEDULED INSPECTION, A CRACK WAS FOUND IN THE NACELLE ANGLE. UPON FURTHER INVESTIGATION, IT WAS FOUND THAT THE CRACK WAS BETWEEN THE 2 RIVETS THAT EXTENDED THRU THE WING SKIN INTO CAP (P/N 67097-002 OR -003 DEPENDENT ON SIDE) WHICH IS ATTACHED TO A WEB (PN 67079-000 OR 001 DEPENDENT ON SIDE) THAT THE MAIN GEAR AFT ATTACH POINT IS MOUNTED. IT IS SUSPECTED THAT THIS IS A FAILURE DUE TO FATIGUE.

Part: DRAG LINK — BROKEN (NLG)

NOSE GEAR DRAG LEG BROKEN AT FWD ATTACH POINT BREAKING THROUGH BOLT HOLE. THIS FAILURE LEAD TO THE ACFT INDICATING THAT ALL GEARS WERE DOWN AND LOCKED. DURING LANDING THE NOSE GEAR FOLDED FWD CAUSING DAMAGE TO THE FWD BULKHEAD AND CAUSING 2 PROP STRIKES. IF THIS FWD ATTACH POINT WERE BUILT UP MORE WHICH THERE IS ROOM, THAT WOULD HELP WITH THIS ISSUE.

Part: WIRE HARNESS — BROKEN (MLG DWNLK SWITCH) · airframe 3,313 hrs

LT MLG WIRING HARNESS WIRES ON DOWN LOCK SWITCH BROKE AT SWITCH CAUSING AN INDICATION OF UNSAFE GEAR.

Part: WIRE HARNESS — BROKEN (DOWNLOCK SWITCH) · airframe 2,956 hrs

LT MLG WIRING HARNESS WIRES ON DOWN LOCK SWITCH BROKE AT SWITCH CAUSING AN INDICATION OF UNSAFE GEAR.