Aeroflight Academy of Aviation, Inc.

ON THE 2ND LEG OF A FLIGHT, THE PILOT EXPERIENCED AN OCCASIONAL MISFIRE THAT BECAME MORE REGULAR ADJUSTING MIXTURES AND CHECKING MAGNETOS. FAILE TO ISOLATE PROBLEM SO THE DECISION WAS MADE TO DIVERT WHERE AN UNEVENTFUL LANDING WAS MADE. MX WAS DISPATCHED FOR REPAIRS. THEY CONDUCTED A GROUND RUN AND COULD NOT DUPLICATE MISFIRE. FUEL FLOWS, MANIFOLD PRESSURES AND MAGNETO TIMING AND CYLINDER COMPRESSIONS WERE NORMAL. FURTHER TROUBLESHOOTING REVEALED A COUPLE OF SPARK PLUGS THAT APPEARED WEAK. NEW SPARK PLUGS WERE INSTALLED. GROUND RUNS WERE PERFORMED AND ACFT WAS DETERMINED AIRWORTHY. SUBSUQUENT NON-REVENUE FLIGHT WAS NORMAL. NO FURTHER MX ACTION WAS REQUIRED.

LANDING GEAR FAILED TO FULLY RETRACT. FOUND ELECTRIC MOTOR ON HYDRAULIC POWERPACK FAILED. REPLACED POWER PACK AND LANDING GEAR FUNCTIONED PROPERLY. (K)

NR 3 CYLINDER ON THE LT ENGINE CRACKED COMPLETELY AROUND THE HEAD, APPROX 1.25 INCHES ABOVE THE BASE OF THE HEAD. THE CRACK WAS COMPLETELY AROUND THE CIRCUMFERANCE OF THE HEAD AND ALLOWED THE HEAD TO SLIP OFF OF THE BARREL, HALF AN INCH. THE PROP WAS FEATHERED, ENGINE SHUTDOWN AND A SAFE LANDING WAS MADE. NO OTHER DAMAGE TO THE ENGINE OR AIRCRAFT. CYLINDER WAS ON ITS 3RD RUN, HAD BEEN PREVIOUSLY REBARRELED AND BORED .010 OVERSIZED AT THE LAST OVERHAUL. (K)

WHILE FLYING AT 170 KIAS, THE PILOT NOTED HE HAD TO REDUCE POWER TO MAINTAIN 170 KIAS. SHORTLY AFTER THAT THE AIRCRAFT`S (STICK SHAKER) ACTIVATED. INSPECTION REVEALED SEVERELY DETERIORATED PLASTIC TUBING FROM FWD PRESSURE BULKHEAD TO AIR DATA COMPUTER. LINES WERE REPLACED. (K)