337Skymaster

Parts most often named Cylinder (5) · Piston (3) · Piston Pin (2) · Exhaust Valve (2)

ENGINE RUNNING ROUGH. COLD COMPRESSION CHECK SHOWED -0- COMPRESSION ON NR 6 CYLINDER. AIR LEAKING PAST EXHAUST VALVE. DISASSEMBLY REVEALED EXHAUST VALVE STUCK IN OPEN POSITION. EVIDENCE OF PISTON STICKING EXHAUST VALVE. THIS IS THE SECOND OCCURANCE OF THIS CONDITION ON THIS ENGINE. (K)

ENGINE RUNNING ROUGH. PERFORMED COLD COMPRESSION CHECK. COMPRESSION WAS ZERO. AIR LOOKING PAST EXHAUST VALVE. REMOVED ROCKER ARM COVER, NOTED EXHAUST VALVE STICKING IN OPEN POSITION. REMOVED CYLINDER. PISTON HAD STRUCK EXHAUST VALVE. REPLACED CYLINDER AND PISTON. PISTON WAS DIFFERENT THAN ORIGINAL PN WAS THE SAME, TOP OF PISTON WAS CONCAVE WHERE AS ORIGINAL PISTON WAS FLAT. (K)

(CAN) AFTER LANDING PILOT WAS TAXIING FOR SHUTDOWN WHEN HE HEARD A BANKING NOISE AND REAR ENGINE ROUGHNESS. INSPECTION REVEALED A DENT IN VALVE COVER. COVER REMOVED AND FOUND BOTH ROCKER SHAFT HOLD DOWN STUDS SHEARED. IT HAS BEEN NOTED BEFORE ON OTHER AIRCRAFT THAT ROCKER SHAFT HOLD DOWN NUTS HAVE BEEN STRIPING EASILY EVEN WITH TELEDYNE CONTINENTAL NEW ROCKER SHAFT HOLD DOWN NUTS TORQUE VALVES. . .

Parts most often named Dowel (4) · Cylinder Pin (3) · Locknut (2) · Counterweight (1)

Parts most often named Control Cable (15)

FOUND BOTH OF THE RT WING FLAP EXTEND CABLES WITH BROKEN INTERNAL WIRES. CABLES HAD TO BE REMOVED AND TWISTED AGAINST THEIR NORMAL WIND TO FIND THE TROUBLE. BOTH WERE DAMAGED AT THE POINT WHERE THEY GO AROUND THE BELLCRANKS IN THE WING, ABOUT 2 INCHES FROM THE CABLE TENSION ADJUSTING NUT.

(CAN) DURING INSPECTION IT WAS DICOVERED THAT THESE CABLES (2EA. 1 LT AND 1 RT) WERE FRAYED WHERE THE CABLE BENDS AROUND THE FLAP CABLE QUADRANT LOCATED IN THE WING TRAILING EDGE.

(CAN) DURING INSPECTION IT WAS DISCOVERED THAT THESE CABLES (2EA. 1 LEFT AND 1 RIGHT) WERE FRAYED WHERE THE CABLE BENDS AROUND THE FLAP CABLE QUADRANT LOCATED IN THE WING TRAILING EDGE.

Parts most often named Hub (10) · Ferrule (2) · Bushing (1)

(CAN) PROP RECEIVED FOR O/H. UPON INSPECTION CORROSION PITS WERE FOUND IN THE PROP MOUNTING FLANGE. THIS DAMAGE WAS TOO DEEP TO BE REMOVED WITHIN MANUFACTURERS SPECIFICATIONS. PROP HAS EXCEEDED THE MANUFCTURERS RECCOMENDED CALENDAR TBO BY 31 MONTHS.

THE PART WAS REJECTED PER MCCAULEY SB 176C AND THE PRODUCT SUPPORT STAFF AT MCCAULEY PROPELLER SYSTEMS. THE HUB WAS REJECTED BECAUSE THE BLADES SHOW EVIDENCE OF PRE-STRAIGHTENING.

A CRACK WAS FOUND IN THE REAR OF BLADE SOCKET NR 2 DURING A DYE PENETRANT INSPECTION. THE HUB WAS RED TAGGED AND RETIRED FROM [S/N removed]. THE PROPELLER HAD BEEN IN [S/N removed] 3 YEARS SINCE LAST OVERHAUL AND AD 91-15-04 HAD BEEN C/W AT THAT TIME.

Parts most often named Crankcase (6) · Crankshaft (2) · Through-Bolt (1) · Stud (1)

DURING A ROUTINE INSP, DISCOVERED A 2.5" CRACK IN THE ENGINE CASE RUNNING FWD FROM NR 5 C4L BASE TO THE FRONT BEARING AREA. THE CRANK WAS ALLOWING ENGINE OIL SEEPAGE AT THE CRACK AREA. THE ENGINE WAS REMOVED FROM [S/N removed] AND SENT TO O/H.

(CAN) THE INITIAL PROBLEM WAS AN OIL LEAK FOUND DURING INSPECTION, AFTER SEVERAL ENGINE GROUND RUN-UPS, CRACK OF 2 INCHES FOUND FWD OF CYLINDER NR 5 ON CRANKCASE UPPER SECTION, ENGINE REMOVED AND SEND TO REPAIR SHOP.

AFTER LANDING FROM A ROUTINE COMPANY FLIGHT, THE MAINTENANCE ENGINEER NOTED MORE THAN NORMAL OIL ON THE LT REAR COWLING. UPON FURTHER INVESTIGATION, A 3 INCH CRACK WAS DETECTED ON THE CRANKCASE HALF STARTING FROM THE ENGINE DRIVEN FUEL PUMP BOSS TO THE CRANKCASE THRU BOLT. THE ENGINE IS BEING REMOVED AND SENT TO AUTHORIZED REPAIR SHOP FOR REPAIR.

Parts most often named Blade (8) · Bearing (1) · Base Assy Pin (1) · Retain Nut (1)

(CAN) PROPELLER RECEIVED FOR CORROSION INSPECTION. PROPELLER BLADES WERE REPAIRED IN THE FIELD AND FOUND TO BE BELOW MANUFACTURERS MINIMUM WIDTHS (LIMITS).

(CAN) PROPELLER RECEIVED FOR FIVE YEAR CORROSION INSPECTION. INSPECTION FOUND NR 1 BLADE BEARING RACE CORRODED. BEARING RACE REPLACED.

Parts most often named Clamp (2) · Capacitor (1) · Drive Gear (1) · Points (1)

(CAN) DURING OPS CHECKS OF THE ENGINE AFTER ENGINE INSPECTION, IT WAS NOTED THAT THE FRONT ENGINE LT MAG HAD A DROP OF 250. THE MAGNETO WAS REMOVED AND DISASSEMBLED FOR INSPECTION. IT WAS THEN NOTICED THAT THE CLAMPS THAT BOTH OF THE CLAMPS THAT HOLD DOWN THE COIL, PN 10-50765, HAD BROKEN OFF. THE LOOSE PIECES INSIDE THE MAGNETO CAUSED DAMAGE TO THE HOUSING AND DISTRIBUTOR GEAR.

(CAN) ON ENGINE SHUTDOWN PILOT NOTICES OIL LEAKING. INSPECTION REVEALED MAGNETO HAD A HOLE NEAR MOUNTING FLANGE. THE MAGNETO WAS REMOVED AND FOUND THAT 1 OF THE FLYWEIGHTS HAD CRACKED BY MOUNTING PIN AND THE FLYWEIGHT HAD EXITED THE MAGNETO THROUGH THE CASE. THE MAGNETO TO ENGINE DRIVE WAS ALSO CRACKED DUE TO THE FLYWEIGHT EXITING.

ON INSP OF OIL SCREEN METAL WAS FOUND AND INSP WAS CARRIED OUT AND FOUND THAT THE MAGNETO DRIVE GEAR WAS MISSING SEVERAL TEETH AND THE REST OF THE TEETH WHERE WORN DOWN TO ALMOST A KNIFE EDGE. IT IS ALMOST LIKE THE GEAR WAS NOT HARDENED PROPERLY.

Parts most often named Wheel (5) · Bolt (2)

NOSE WHEEL FAILED ON LANDING. THE ASSEMBLY APPEARED TO HAVE COME APART WITH THE HUB AND THE SIDE PIECES SEPARATED. A REVIEW OF THE LOGS SHOWED THAT THE WHEEL HAD BEEN ON THE AIRCRAFT SINCE NEW IN 1973.

WHEEL ASSEMBLY RETURNED FOR LOOSE TIE BOLTS OF 18 INSTALLED 14 WERE FOUND LOOSE 2 MISSING. MFG HAS NOW RELEASE [S/N removed] LETTER F6137-32--843 IN HOPES THIS WILL RESOLVE.

(AUS) NOSE AND MAIN WHEEL HALVES (5OFF6) CORRODED WITH BEARINGS SPINNING IN THE WHEEL HALVES. CORROSION ALSO FOUND IN AREA OF THE FELT SEALS.

Parts most often named Pump (6) · Stop Pin (1)

(CAN) THE PILOT REPORTED THAT HIS MIXTURE CONTROLS WHERE A FULL KNOB OUT FROM EACH OTHER AND FUEL FLOWS WHERE OUT FROM EACH OTHER DURING GROUND RUN. INSPECTION REVEALED THE MIXTURE STOP PIN ON THE REAR ENGINE FUEL PUMP HAD COME OUT. THE MIXTURE CONTROL COULD GO BEYOND THE STOP LIMITS AFFECTING ENGINE FUEL MIXTURES. WE HAVE NOTED SEVERAL OTHER STOP PINS EITHER LOOSE OR COMING PART WAY OUT. DISCOVERY AIR FIRE [S/N removed] HAS GENERATED AN INTERNAL SB INSPECTING THESE PUMP PINS AS THIS IS A [S/N removed] ISSUE.

HIGHWING TANK CONNECTED TO THE FUEL PUMP INLET PORT. THE NONE DRIVE FUEL PUMP LEAKS REGARDLESS THE MIXTURE LEVER POSITION. WITH MIXTURE LEVER IN IDLE CUTOFF, FUEL FLOW IS SAME AS IN FULL RICH. 3 TO 4 MM/0.012IN TO 0.016IN AWAY FROM THE IDLE CUT OFF STOP, THERE IS THE LOWEST FUEL FLOW AT ALL.

WITH A HIGHWING TANK CONNECTED TO THE FUEL PUMP INLET PORT, THE NONE DRIVEN FUEL PUMP LEAKS REGARDLESS THE MIXTURE LEVER POSITION. WITH THE MIXTURE LEVER IN IDLE CUT OFF, THE FUEL FLOW IS THE SAME AS IN FULL RICH. 3 TO 4 MM/0.012IN TO 0.016IN/ AWAY FROM THE IDLE CUT OFF STOP, THERE IS THE LOWEST FUEL FLOW.

Parts most often named Alternator (5) · Housing (1) · Drive Assembly (1)

FRONT ENGINE CHARGING SYSTEM, INTERMITTENT, THEN CONSTANT ALTERNATOR INOPERATIVE LIGHT. CHECKED CHARGING SYSTEM IAW MM. FOUND THREE BOLTS THAT HOLD THE ALTERNATOR FRAME TOGETHER FOUND LOOSE DESPITE FACTORY SAFETY WIRE BEING SECURE AND UNTOUCHED. DISASSEMBLY OF UNIT SHOWED FRAME HAD WORKED LOOSE ALLOWING THE STATOR TO CONTACT THE ROTOR AND THE STATOR ROTATED IN THE FRAME PULLING MAIN WIRES OUT.

(CAN) ON INSPECTION OF ALTERNATOR HOUSING 2 RIBS WERE FOUND CRACKED COMPLETELY THROUGH. THERE HAVE BEEN TWO OTHER SIMILAR ALTERNATORS FOUND WITH CRACKED RIBS.

OWNER OF THIS AIRCRAFT EXPERIENCED FWD ENGINE ALTERNATOR FAILURE (AS INDICATOR BY FAILURE LIGHT) DURING FLIGHT. TECHNICIAN AND OWNER REMOVED ALTERNATOR FROM ENGINE AND DISCOVERED THE DRIVE SHAFT SHEARED. THE GEAR RETAINING BOLT HAD RUBBED INTERNALLY AND BUSTED A PIECE OF THE COTTER PIN OFF, WHICH WAS FOUND ON THE MAGNETIC OIL DRAIN PLUG. THE DRIVE GEAR ALSO DISPLAYED SIGNS OF WEAR. THE ALTERNATOR SHAFT FAILURE APPEARS TO BE A MATERIAL DEFECT.