PA-23Apache · Aztec

Parts most often named Bearing (8) · Split Bearing (8) · Clamp (5) · Rod (3)

CYLINDER (PN B2452-1) SEPARATED FROM PROPELLER ON GROUND RUN. INSPECTION SHOWED THREAD DAMAGE OF CYLINDER. AFTER DISCUSSION WITH MANUFACTURER THE LIKELY CAUSE IS DUE TO HIGH PRESSURE FROM GOVERNOR, USUALLY CAUSED BY STICKING PRESSURE RELIEF VALVE.

(AUS) PROPELLER BLADE CLAMP BOLTS NOT IN SAFETY. NO SPACERS BETWEEN SPINNER BACKPLATE AND PROPELLER HUB. PROPELLER BLADES CONTACTINGBACKPLATE WHEN BLADE IS IN THE FEATHER POSITION.PERSONNEL/MAINTENANCE ERROR.

(CAN) PILOT REPORTED PROP RPM FLUCTUATIONS ON PREVIOUS FLIGHT. ON NEXT FLIGHT REPORTED NO PROP CONTROL WITH PROP LEVER. PILOT ABORTED FLIGHT. INSPECTION FOUND BOTH VALVE STEM AND DUST COVER LYING INSIDE THE PROP SPINNER DOME COVER, PROPELLER ACCUMULATOR PRESSURE AND LEAK CHECK CARRIED OUT AT 100 HOUR INSPECTION 40.8 HOURS PRIOR TO THIS OCCURRENCE. NO FAULT WAS FOUND AT THAT TIME.

Parts most often named Bearing (9) · Magneto (8) · Gear (2) · Breaker Points (1)

ENGINE BECAME INCREASINGLY DIFFICULT TO START, CHECKED IGNITION TIMING AND FOUND LT MAGNETO OUT OF TOLERANCE. INSPECTED LT MAGNETO, POINTS FAILED TO OPEN DUE TO EXCESSIVLY WORN BREAKER POINT CAM. 87 HOURS SINCE NEW

SUBJECT PART APPEARS TO HAVE NOT RETAINED ITS LOWER BEARING THAT SUPPORTS THE DISTRIBUTOR GEAR. THE PART WAS FOUND TO BE BURNED AND THE BEARING HOLE MISSING THE BEARING AND ROUNDED OUT WHICH CAUSED THE MAGNETO TO FAIL AND PREVENTED ENGINE STARTUP. JUST PRIOR TO THIS, ENGINE STARTUP HAD BEEN DIFFICULT, HOWEVER, MAG DROP AND PERFORMANCE WERE NORMAL. (K)

CUSTOMER COMPLAINED OF A VIBRATION ON RT ENGINE. INSPECTION REVEALED CAGE FAILURE OF THE RT MAGNETO DRIVE GEAR BEARING (PN 67542). CAUSE OF CAGE FAILURE NOT KNOWN. CANNOT RECOMMEND ACTION TO PREVENT REOCCURRENCE. (K)

Parts most often named Bolt (9) · Drag Link (7) · Spring (2) · Support Bracket (1)

(CAN) RT LANDING GEAR DOWN LOCK SPRING (P/N 487-312) BROKE AND LODGED ITSELF BETWEEN THE HOOK AND THE LOCK OF THE UPLOCK BOX. THE GEAR COULD NOT MOVE AND THEN THE GEAR LIGHT DID NOT COME ON. (TC NR 20070814003)

DURING THE INVESTIGATION, IT WAS DISCOVERED THAT THE RT MLG UPPER DRAG LINK ASSY HAD FAILED AT THE ATTACHMENT POINT FOR THE MLG DOWNLOCK LATCH ASSY. A VISUAL INSPECTION OF THE BROKEN DRAG LINK SHOWED THAT THE ASSY HAD A METAL FATIGUE CRACK ALONG THE CIRCUMFERENCE OF THE COMPONENT. THE CRACKED AREAS SHOWED EVIDENCE OF CORROSION THAT APPEARS TO HAVE BEEN THERE FOR A LONG PERIORD OF TIME. (K)

DUE TO PREVIOUS FAILURE OF RT DRAG LINK, LT MAIN LANDING GEAR DRAG LINK WAS REMOVED, PAINT STRIPED AND INSPECTED WITH ZYGLOW. A SMALL CRACK WAS NOTED EXTENDING INTO A WELD IN THE SAME AREA THAT THE OTHER (RT MLG LINK) HAD BROKEN. DRAG LINK WAS REPLACED WITH A NEW OEM PART AND GEAR SYSTEM CHECKED FOR RIG AND PROPER OPERATION. THE AC HAD BEEN PAINTED RECEINTLY AND DETECTING A CRACK IN THIS AREA WOULD HAVE BEEN IMPOSSIBLE UNLESS THE LINK WAS STRIPPED AND ZYGLOW INSPECTED. (K)

Parts most often named Cylinder (11) · Plug (3) · Cylinder Head (3) · Ring (1)

ACFT HAD JUST DEPARTED ON PART 91 REPOSITIONING FLIGHT BACK HOME. APPROX 10 OR SO MINUTES AFTER DEPARTURE, WHILE LEVEL IN CRUISE FLIGHT AT 7000', RT ENGINE EXPERIENCED SUDDEN POWER LOSS. ENGINE WAS SHUTDOWN, PROP FEATHERED, AND ACFT RETURNED FOR LANDING. FOR UNKNOWN REASON, PISTON JAMMED IN CYLINDER, POSSIBLY DUE TO RING DEFECT, CAUSING THE BOLTS TO SHEAR AND THE CASE TO CRACK. THERE WAS NO EVIDENCE OF OIL LEAKS OR OTHER ABNORMALITIES PRIOR TO THE OCCURENCE.

NR 3 CYLINDER DEPARTED THE ENGINE AFTER FAILURE OF THE CYLINDER HOLD DOWN NUTS TO MAINTAIN PROPER TORQUE. (3) ADDITIONAL CYLINDERS FROM THE SAME ENGINE WERE INSPECTED REVEALING (5) MORE UNDER TORQUED CYLINDER HOLD DOWN NUTS.

(CAN) THE TECHNICIANS OBSERVED AN ABNORMAL LOSS OF COMPRESSION ON SOME CYLINDERS FOLLOWING A ROUTINE INSPECTION. THEY REMOVED THE CYLINDERS AND SENT THEM TO OUR SHOP FOR INVESTIGATION. WE OBSERVED A DELAMINATION OF CHROME PLATING ON THE CYLINDER RINGS. WE REPAIRED THE CYLINDERS BY REPLACING THE DEFECTIVE PARTS WITH A NEW PARTS. THE MANUFACTURER HAS BEEN ADVISED ABOUT THE DEFECTIVE RINGS. (TC NR 20060817006)

Parts most often named Wheel (14) · Wheel Half (2)

WHILE REMOVING THE WHEEL FROM THE RIGHT MAIN LANDING GEAR FOR ANNUAL INSPECTION, THE AXLE NUT WAS BINDING. REMOVED ALL AIR FROM THE TIRE AND THE BINDING WAS RELEASED. FOUND THE WHEEL CRACKED WITH THREE OF THE SIX THREADED INSERTS THAT HOLD THE WHEEL HALVES TOGETHER BROKEN OUT.

DURING A ROUTINE INSPECTION THE AMT ENCOUNTERED DIFFICULTY WHILE REMOVING THE LT MAIN GEAR WHEEL ASSEMBLY AXLE RETAINING NUT. HE STOPPED AND DEFLATED THE TIRE. THE WHEEL WAS THEN REMOVED EASILY. FOLLOWING REMOVAL THE WHEEL WAS FOUND TO BE SEVERELY CORRODED AND ALL BUT ONE WHEEL-HALF RETAINING BOLT HAD FAILED. THE LOG BOOK ENTRY INDICATED THAT THE WHEEL HAD LSAST BEEN DISASSEMBLED 217 HOURS AGO. (K)

DIFFICULTY WAS ENCOUNTERED WHILE AN AMT WAS REMOVING THE RETAINING NUT FROM THE AXLE ON THE RT MAIN GEAR OF AC. HE STOPPED AND DEFLATED THE TIRE. THE WHEEL ASSEMBLY WAS THEN REMOVED WITHOUT RESISTANCE. AFTER REMOVAL ALL BUT ONE OF THE ASSEMBLY RETAINING BOLTS WERE FOUND BROKEN AND THE WHEEL HALVES WERE ALSO BROKEN. CORROSION CAUSED THE PROBLEM. THE WHEEL HAD ACCUMULATED 217 HOURS SINCE IT WAS LAST DISASSEMBLED AND INSPECTED. TT ON THE WHEEL IS UNKNOWN. THE ENTIRE WHEEL ASSEMBLY WAS REPLACED. (K)

Parts most often named Crankcase (4) · Connect Rod (2) · Bearing (1) · Bolt (1)

RIGHT ENGINE STOP DURING FLIGHT. FOUND SPRING PIN OF CRANKSHAFT GEAR BROKEN. WHEN THE CRANKSHAFT WAS REMOVED, THE CHANKSHAFT BOLT SHEARED AND BROKE EASILY. THIS BOLT IS SUBJECT TO AD 2002-23-06AND AD 2004-04-25C. THE NEW BOLT KIT WAS REPLACED (MARCH 18, 2003 - REFER TO PURCHASE ORDER 11618) 343.4 HOURS BEFORE THE ENGINE STOP INCIDENT. THE NEW BOLT KIT P#N 05K19987 WERE SUPPLIED BY AVIALLON PURCHASE ORDER 11600 (01/22/2003)

ENGINE SUFFERED CATASTROPHIC FAILURE. AT ENGINE TEARDOWN, THE NR 6 PISTON (FRAGMENTED), PISTON RINGS, CONNECTING ROD, ROD CAP, BEARINGS, ROD BOLTS, AND NUTS WERE FOUND IN THE OIL SUMP. ONE ROD BOLT WAS BROKEN AND ITS NUT WAS ON IT. THE OTHER ROD BOLT WAS NOT BROKEN AND ITS NUT WAS RECOVERED FROM THE OIL SUMP. ONE ROD BOLT WAS BROKEN AND ITS NUT WAS RECOVERED FROM THE OIL SUMP. POSSIBLE CAUSE IS A DEFECTIVE LOCK NUT. RECOMMEND CHECKING ROD NUT DRAG TORQUE WHEN ASSEMBLING CONNECTING RODS.

(CAN) AIRCRAFT WAS AIRBORNE FOR APPROXIMATELY 10 MINUTES WHEN ENGINE OIL TEMPERATURE OBSERVED HIGHER THAN USUAL. ENGINE SEEMED TO RUN ROUGH, AIRCRAFT RETURNED TO AIRPORT AND LANDED WITHOUT INCIDENT. UPON INSPECTION FOUND NR 6 CYLINDER IN AN ALMOST SEIZED CONDITION. RINGS WERE SEIZED TO PISTON. CYLINDER ASSEMBLY REMOVED FROM [S/N removed] AND NEW ASSEMBLY INSTALLED. GROUND RUNS COMPLETED NO FURTHER FAULTS NOTED. (TC NR 20060206011)

Parts most often named Hub (11) · Hub Arm (1) · Spring (1) · Propeller (1)

DURING INSPECTION, NOTICED THE PRELOAD SHELF WAS ROLLED. EVIDENCE SHOWS HUB ENDURED EXCESSIVE FORCES. HUB WAS RETIRED FROM [S/N removed]. (X)

PROPELLER WAS LEAKING GREASE. DURING TEAR DOWN FOUND WATER IN HUB. WATER HAD CORRODED SPRING. SPRING SUBSEQUENTLY BROKE INTO FOUR PIECES. ALSO, FOUND BOTH BLADE SHANKS [S/N removed] CORRODED IN AREA ADDRESSED BY AD 77-12-06. LAST DOCUMENTED OVERHAUL ON PROP WAS 10/85. (X)

(CAN) RIGHT HAND PROPELLER HARD TO CONTROL, ENGINE SHUTDOWN, AND AIRCRAFT RETURNED TO BASE. PRESSURE CHECK CARRIED OUT ON PROPELLER AND THERE WAS NO NITROGEN PRESSURE IN THE CYLINDER. IT IS SUSPECTED THE VALVE WAS LEAKING. THE VALVE WAS REPLACED, THE CYLINDER CHARGED WITH NITROGEN AND THE ASSEMBLY WAS CHECKED [S/N removed].

Parts most often named Heater (3) · Valve (2) · Regulator (2) · Tube (2)

AIRCRAFT RECEIVED FROM NEW OWNER WANTING HEATER MADE OPERATIONAL: TOTALLY DEACTIVATED. REPLACED HEATER ASSY DUE TO EXTREME DETORATION. FUEL REGULATOR REPLACED DUE TO LEAKAGE AND FAILURE TO REGULATE FOUND INLET PORT PARTIALLY PLUGGED BY CORROSION BY-PRODUCTS AND REMNANTS OF DAMAGED THREADS. N/E REPAIRABLE. (K)

(CAN) DURING REMOVAL OF A BIRDS NEST IN THE FRESH AIR INTAKE LOCATED IN THE NOSE OF THE AIRCRAFT THE HEATER EXHAUST TUBE WAS FOUND TO BE UNSERVICEABLE. THE TUBE ITSELF IS A (WOUND) TUBE AND THE WINDINGS NEAR THE ATTACH POINT HAD SEPARATED THAT WOULD ALLOW HOT EXHAUST TO CONTACT THE TUBE SHROUD. (TC NR 20060602002)

UNIT WAS INSPECTED DURING A 100 HOUR INSPECTION USING S/B. FUEL STAINS WERE FOUND, BAD NO FUEL, AROUND BOTH TOP AND BOTTOM GASKETS. UNIT WAS REMOVED FROM [S/N removed].

Parts most often named Pipe (5) · Exhaust Stack (4) · Crossover Pipe (1) · Collector (1)

LT ENGINE EXHAUST BACK PRESSURE SEPARATED (PN LW 11657) WASTE GATE MALE FROM (PN LW 11656) FEMALE. (PN LW 1165) U BOLT WAS NOT LOOSE.

DURING REPAIR OF MASSIVE OIL LEAK ON LEFT ENGINE, FOUND EXHAUST STACK MISSING ON NR3 CYLINDER. STACK BROKEN AT FLANGE AND WAS LYING IN COWL. AIRCRAFT HAD BEEN FLYING THIS WAY FOR SEVERAL HOURS. STACK ON NR2 CYLINDER WAS CRACK MORE THAN 50 PERCENT AT FLANGE. OTHER IMPROPER REPAIRS NOTED ON OTHER EXHAUST PIPES. AC HAD JUST PREVIOUSLY BEEN ANNUALED. NEW PARTS WERE INSTALLED.

(CAN) BLACK SOOT NOTED ON RIGHT HAND OUTBOARD LANDING GEAR DOOR AND OUTBOARD COWL FLAP. EXHAUST STACK FOUND SEPARATED. NO OTHER LOOSE AREAS NOTED. SUBMITTER SUGGESTS THAT THE REAR STACK WAS TOO SHORT AND THE SPRING ACTION OF REAR SUPPORT CAUSED THE SEPARATION OR VIBRATION OR BACK FIRE ON PREVIOUS START.

Parts most often named Blade (9) · Blades (1) · Retainer (1) · Counterweight (1)

PROPELLER WAS DISASSEMBLED FOR O/H AND THE FOLLOWING WAS FOUND AT INSPECTION, THE PITCH CHANGE KNOBS ON BOTH BLADES ARE CORRODED AND ONE PITCH CHANGE KNOB HAS BEEN REWORKED BELOW MINIMUM SPECIFICATIONS. PROPER O/H TECHNIQUES AND INSP CRITERIA WOULD HAVE CAUGHT THE REWORKED PITCH CHANGE KNOB AND OVERHAULING OF THE PROPELLER AT RECOMMENDED [S/N removed] TIMES WOULD HAVE PREVENTED THE CORROSION OF THE PITCH CHANGE KNOB. (K)

MT INSPECTION REVIELD A CRACK APPROX .1250 INCH LONG ON BOTH SIDES OF RACE MATERIAL. PROPELLER WAS PURCHASED AS A OVERHAULED PROPELLER WITHOUT RECORDS. REPORTED LOST. PURCHASER SUBMITTED PROPELLER FOR OVERHAUL. IN ADDITION TO THIS CRACKED PART, THE BLADES WERE FOUND TO BE 2 INCHES UNDER MINIMUM DIAMETER FOR THE INTENDED APPLICATION.

DURING TRAINING FLIGHT, LEFT PROPELLER WOULD NOT COME COMPLETELY OUT OF FEATHER. THE ENGINE COULD ONLY DEVELOP 1500 RPM. WHEN THE ENGINE WAS SHUTDOWN ON THE GROUND, THE PROPELLER WENT BACK INTO FEATHER REGARDLESS OF THE PROP CONTROL POSITION. UPON PROP DISASSEMBLY, ONE OF THE FEATHER LATCH WEIGHTS WAS FOUND BROKEN IN HALF. UNDER EXAMINATION THE METAL IN THE BREAK APPEARS VERY GRANULAR IN NATURE AND UNDER MAGNIFICATION THERE IS RUST IN SOME OF THE VOIDS BETWEEN METAL GRAINS.