EnstromF-28 · 280 · 480

Parts most often named Cylinder (3) · Intake Rocker (1) · Valve Guide (1) · Rocker Cover (1)

DURING CYLINDER OVERHAUL A DAMAGE SEAT POCKET CUTTER USE USED. THIS RESULTED IN A VALVE SEAT POCKET THAT MEASURED WITHIN LIMITS BUT LACKED THE PROPER SURFACE CONTACT. AFTER APPROXIMATELY 3 HOURS OF ENGINE OPERATION, THE VALVE SEAT CAME OUT CAUSING THE INTAKE VALVE TO BREAK. THIS CAUSED A LOSS OF ENGINE POWER AND THE HELICOPTER MADE A HARD LANDING. HELICOPTER WAS DESTROYED BY FIRE. (K)

EXHAUST VALVE GUIDE BROKE UP LETTING THE EXHAUST VALVE LOOSEN IN THE CYLINDER. EXHAUST VALVE DID NOT FAIL. PIECES FROM THE GUIDE JAMMED THE TURBOCHARGER TURBINE WHEEL DESTROYING THE TURBOCHARGER AND CAUSING LOSS OF POWER.

LOOSE RETAINING NUTS WORKED OFF STUDS ALLOWING THE PORT COVER TO FALL OFF AND NR 2 CYLINDER INTAKE VALVE ROCKER ARM SHAFT TO FALL OUT OF THE ENGINE RESULTING IN A CRASH LANDING. SUGGEST REVIEWING ENSTROM PRODUCTION CERTIFICATE AND TIGHTEN THE INSPECTION PROCEDURE TO REDUCE THE CHANCES THAT ANOTHER HELICOPTER WILL BE RELEASED WITH HIDDEN LOOSE PARTS.

Parts most often named Universal Hsng (6) · Yoke (1) · Swashplate Yoke (1)

MOUNTING WEBS FOR CONTORL ROD BEARINGS AND UNIVERSAL JOINT OF LOWER SWASHPLATE FOUND CRACKED AT INSPECTION. THIS IS A PRIMARY FLIGHT CONTROL PART. THIS PART HAS A RETIREMENT LIFE OF 17,700 HOURS. PART NON-REPAIRABLE. REPLACED WITH NEW PART 28-16119-1.

MOUNTING WEBS FOR CONTROL ROD BEARINGS AND UNIVERSAL JOINT OF LOWER SWASHPLATE FOUND CRACKED AT INSPECTION. THIS IS A PRIMARY FLIGHT CONTROL PART. THIS PART HAS A RETIREMENT LIFE OF 17,700 HOURS. PART NON-REPAIRABLE. REPLACED WITH NEW PART 28-16119-1.

CRACKS FOUND BETWEEN CONTROL ROD AND UNIVERSAL YOKES. CRACK RUNS DOWN THE WEB BETWEEN BOTH AT 2 LOCATIONS. THIS IS SECOND FOUND THIS MONTH. THE OTHER CRACKED SWASHPLATE IS [S/N removed] WITH SIMILAR TIME IN [S/N removed]. CRACKED SWASHPLATE YOKE REMOVED FROM [S/N removed]. NEW YOKE PURCHASED AND INSTALLED.

Parts most often named Capacitor (2) · Coil (1) · Points (1) · Contact Points (1)

POINTS CLOSED AND MAGNETO QUIT DUE TO MELTED CAM FOLLOWER. LYCOMING FACTORY OVERHAULED ENGINE, TELEDYNE CONT FACTORY OVERHAULED MAG, AND SLICK OVERHAULED HARNESS.

PILOT REPORTED A ONE PER REV VIBRATION ON BURP IN HELICOPTER DURING FLIGHT. DURING A MAGNETO CHECK, ENGINE WOULD CONTINUE TO RUN WITH IGNITION IN OFF POSITION. MAGNETO WAS REMOVED AND SENT TO ARN-AIR FOR INSPECTION. IT WAS FOUND THAT ONE CONDENSER FAILED BURNING OUT THE POINTS. THE OTHER CONDENSER HAD AN OPEN CIRCUIT AND WOULD HAVE FAILED ALSO. BOTH CONDENSERS AND POINTS HAD TO BE REPLACED IN THIS. MAGNETO DATE CODE: 98-23.

COMPLAINT WAS 'MISFIRE' AT CRUISE POWER. SYMPTOM WAS NOSE YAW AT ERRATIC INTERVALS. NORMAL PREFLIGHT RUN-UP CHECK SHOWED NO PROBLEM. MAGNETO CHECK AT HOVER POWER CAUSED ENGINE FAILURE WHEN 'LEFT' MAGNETO POSITION WAS SELECTED. RECORDS INDICATE THIS COIL HAS BEEN IN [S/N removed] AT LEAST SINCE ENGINE MAJOR OVERHAUL IN 1987.

Parts most often named Control Cable (4) · Rod End Bearing (2)

BOTH LEFT AND RIGHT TAIL ROTOR CONTROL CABLES SHOW EXCESS WEAR, WHERE THEY PASS THRU THE FAIRLEADS IN THE AFT TALL CONE BULKHEAD. CABLES HAVE BEEN WEARING IN THIS LOCATION CONSTANTLY EVERY 300 TO 400 HOURS. SUGGEST A WIDER CONTACT SURFACE AREA AT THE FAIR LEAD TO REDUCE THE CONCENTRATION OF FRICTION.

AT APPROXIMATELY 12 INCHES FORWARD OF THE TAIL ROTOR, THE LEFT TAIL ROTOR CONTROL CABLE BROKE. NO EVIDENCE OF RUBBING OR CHAFING.

ACCELERATED LATERAL BEARING WEAR. EXCEEDED LIMITS WITHIN 304 HOURS. THIS ROD END NORMALLY LASTS UP TO 1,000 HRS IN [S/N removed]. INSTALLED 2 NEW 01-691-04 BEARINGS.

Parts most often named Crankcase (2) · Bolt (1) · Connecting Rod (1)

NR 2 CONNECTING ROD BOLT FAILED CAUSING CONNECTING ROD TO GO THROUGH CRANK CASE CAUSING MAJOR ENGINE FAILURE. ENGINE DESTROYED. TOP OF BOLT FAILED CAUSING ROD CAP TO BEND BACK AND EVENTUALLY FAIL. THREADED END OF THE BOLT FOUND IN BOTTOM OF ENGINE CASE IN GOOD CONDITION. NO SIGN OF OVERREV COULD BE FOUND IN OTHER BOLTS OR RODS.

A FACTORY OVERHAULED ENGINE WAS INSTALLED. ENGINE STARTED TO MAKE METAL. WHEN OIL WAS DRAINED, IT LOOKED LIKE ALUMINUM PAINT. AN OIL SAMPLE AND FILTER ELEMENT WERE SENT TO FACTORY. FACTORY REQUESTED THAT ENGINE BE REMOVED AND SENT IN FOR REPAIR. TIME ON ENGINE 63.5 HRS SMOH. SUSPECT CAUSE WAS MISALIGNED CRANKCASE. THIS CAUSED PISTON PINS TO SHIFT.

(CAN) A POST FLIGHT INSPECTION FOUND AN OIL LEAK UNDER THE NR2 CYLINDER. FURTHER INSPECTION FOUND A HAIRLINE CRACK APPROXIMATELY 8 INCHES LONG COMING OFF THE LOWER AFT NR2 CYLINDER BASE SHORT STUD. THE ENGINE WAS REMOVED FROM [S/N removed]. THE CRANKCASE HALVES WERE REPLACED AND THE AIRCRAFT RETURNED TO [S/N removed].

Parts most often named Control Cable (4)

Parts most often named Bearing (2) · Bolt (1) · Damper (1)

THE BOLTS THAT FAILED ATTACH INBOARD END OF MAIN ROTOR DAMPER. NEITHER DAMPER CAME LOOSE SINCE THE DESIGN OF THE ROTOR HEAD PREVENTS BOLT FROM COMING OUT ALL THE WAY. REMOVED ALL SAP BOLTS FROM [S/N removed] AND CHECKED TORQUE ON ALL M/R DAMPER BOLTS.

Parts most often named Gearbox (2) · Spacer (1) · Gear (1)

(CAN) DURING ROUTINE 100 HOUR INSPECTION OIL DRAINED FROM T/R GEARBOX, FOUND EXCESSIVE SLUG & METAL PARTICLES ON CHIP DRAIN PLUG. FLUSHED GEARBOX. ADDED FRESH OIL. DISCONNECT INPUT SHAFT & ROTATED INPUT GEAR WITH T/R ATTACHED TO OUTPUT SIDE. NOISE NOTED FROM INPUT SIDE OF GEAR. ASSEMBLY REMOVED FROM [S/N removed] AND RETURNED TO ENSTROM FOR WARRANTY AND EVALUATION. REPORT OF FINDINGS REQUESTED.

PILOT REPORTED NOT BEING ABLE TO SEE OIL LEVEL IN SIGHT GLASS. WHEN SIGHT GLASS REMOVED, A PIECE OF GEAR SET (TOOTH) ABOUT .4375 INCH LONG WAS FOUND INSIDE. ACFT HAD RETURNED FROM FLYING, AND THERE WAS NO VIBS OF NOISE. WEAR MARKS ON BROKEN PART GAVE APPEARANCE OF HAVING BEEN BROKEN FOR QUITE SOME TIME. INSP OF CHIP PLUG SHOWED NO METAL FLAKES OR CHIPS. SUBMITTER RECOMMENDED PULLING SIGHT GLASS AND LOOKING INSIDE TAIL GEARBOX AT EACH 100-HR OIL CHANGE/AD 90-01-06 INSPECTING IT FOR METAL FLAKES. (X)

Parts most often named Wastegate (2) · Adapter (1) · Turbocharger (1)

BUTTERFLY IN WASTEGATE WARPED AND LOSE FROM CRACKED WELDS JAMMING THROTTLE. BUTTERFLY SHAFT WORN AT PIVOT POINTS ALSO CAUSING THROTTLE BINDING. SUBMITTER STATES COMMON TO ALL F28F AND F280FX MODELS. REQUIRES REPLACEMENT OF WASTEGATE.

BUTTERFLY IN WASTEGATE FOUND WARPED AT EACH 100-HOUR INSPECTION. WARPED WASTEGATE AND WORN BUTTERFLY AND SHAFT CAUSE THROTTLE BINDING. BUTTERFLY MUST BE STRAIGHTENED FOR PROPER RIGGING. ON SOME AIRCRAFT, BUTTERFLIES COME OFF OF SHAFT AND BIND THROTTLE. COMMON TO ALL 'F' AND 'FX' MODELS. SUBMITTER STATED WASTEGATES NEED TO BE REPLACED AT 900 HOURS MAXIMUM TIME IN [S/N removed].

Parts most often named Doubler (1) · Bulkhead (1) · Skin (1)