Narrative:

Aircraft was flying from ZZZ1 to ZZZ2. 20 mi north of ZZZ an engine vibration was noticed by pilot and passenger. Precautionary landing was made at ZZZ. Pilot called me and I suggested changing lower spark plugs. After the change; engine ran smooth and flight was continued to ZZZ3. Near ZZZ3; oil pressure gauge needle began moving erratically. Pilot called me and I suggested a loose line in oil pressure indicating system. A mechanic at ZZZ3 found a broken wire in oil pressure sensor and repaired it. (See more details on enclosed letter.) pilot then opted to return to ZZZ1. On the flight north; pilot noticed smoke; oil pressure gauge indicated very high pressure; and a few seconds later the engine stopped. An emergency was declared on 121.5 and a safe landing was made in a cow pasture. There were no injuries and no damage to aircraft except for the engine failure. The reason for the engine failure was a loss of oil due to a broken fitting between the engine and the oil pressure sensor. This fitting had been changed 10 hours previously when a hobbs oil switch was installed. The strength of the fitting; in this application; was evidently insufficient. A number of factors contributed to this incident: the pressure to complete the job in a timely (as determined by owner) manner; unavailability of adequate hardware; the perceived need to keep costs to a minimum; and finally the poor judgement and consequential action taken at that time.

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Original NASA ASRS Text

Title: AN 998.30 DECLARED AN EMER DUE TO ENG FAILURE CAUSED BY A BROKEN OIL FITTING BTWN THE ENG AND OIL PRESSURE XMITTER.

Narrative: ACFT WAS FLYING FROM ZZZ1 TO ZZZ2. 20 MI N OF ZZZ AN ENG VIBRATION WAS NOTICED BY PLT AND PAX. PRECAUTIONARY LNDG WAS MADE AT ZZZ. PLT CALLED ME AND I SUGGESTED CHANGING LOWER SPARK PLUGS. AFTER THE CHANGE; ENG RAN SMOOTH AND FLT WAS CONTINUED TO ZZZ3. NEAR ZZZ3; OIL PRESSURE GAUGE NEEDLE BEGAN MOVING ERRATICALLY. PLT CALLED ME AND I SUGGESTED A LOOSE LINE IN OIL PRESSURE INDICATING SYS. A MECH AT ZZZ3 FOUND A BROKEN WIRE IN OIL PRESSURE SENSOR AND REPAIRED IT. (SEE MORE DETAILS ON ENCLOSED LETTER.) PLT THEN OPTED TO RETURN TO ZZZ1. ON THE FLT N; PLT NOTICED SMOKE; OIL PRESSURE GAUGE INDICATED VERY HIGH PRESSURE; AND A FEW SECONDS LATER THE ENG STOPPED. AN EMER WAS DECLARED ON 121.5 AND A SAFE LNDG WAS MADE IN A COW PASTURE. THERE WERE NO INJURIES AND NO DAMAGE TO ACFT EXCEPT FOR THE ENG FAILURE. THE REASON FOR THE ENG FAILURE WAS A LOSS OF OIL DUE TO A BROKEN FITTING BTWN THE ENG AND THE OIL PRESSURE SENSOR. THIS FITTING HAD BEEN CHANGED 10 HRS PREVIOUSLY WHEN A HOBBS OIL SWITCH WAS INSTALLED. THE STRENGTH OF THE FITTING; IN THIS APPLICATION; WAS EVIDENTLY INSUFFICIENT. A NUMBER OF FACTORS CONTRIBUTED TO THIS INCIDENT: THE PRESSURE TO COMPLETE THE JOB IN A TIMELY (AS DETERMINED BY OWNER) MANNER; UNAVAILABILITY OF ADEQUATE HARDWARE; THE PERCEIVED NEED TO KEEP COSTS TO A MINIMUM; AND FINALLY THE POOR JUDGEMENT AND CONSEQUENTIAL ACTION TAKEN AT THAT TIME.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.