YARMOUTH, MA, USA
N36272
PIPER PA-32RT-300T
AFTER RECEIVING CLEARANCE TO LAND, THE PILOT CALLED THAT HE WAS IN TROUBLE AND WAS GOING DOWN. WITNESSES SAW THE AIRPLANE AT A LOW ALTITUDE, AND HEARD THE ENGINE SPUTTERING AND THEN QUIT. THE LEFT WING STRUCK A TREE; THE AIRPLANE IMPACTED THE GROUND AND WAS COMPLETELY DESTROYED BY THE POST CRASH FIRE. ENGINE TEARDOWN REVEALED THAT THE CYLINDER #1 FUEL INJECTOR LINE HAD FAILED AT THE OUTER DIAMETER (OD) SURFACE AT THE MANIFOLD END NEAR THE B-NUT FITTING. METALLURGICAL EXAMINATION INDICATED THAT THE SEPARATION WAS DUE TO FATIGUE CRACKING THAT ORIGINATED AT THE OD SURFACE OF THE TUBE AT THE EDGE WITH THE BRAZED FILLER METAL. INTERGRANULAR CORROSION WAS OBSERVED AT THE FRACTURE ORIGIN WHICH OCCURRED DURING MANUFACTURE, WHEN THE LINE WAS SENSITIZED NEAR THE BRAZING JOINT. THERE WAS NO EVIDENCE OF CLAMPING OF THE TUBE AT MIDPOINT PER THE ENGINEERING DRAWING.
THE FAILURE OF THE NUMBER ONE CYLINDER FUEL INJECTOR LINE DUE TO FATIGUE CRACKING INDUCED BY CORROSION AND PROPAGATED BY CYCLIC LOADING WHICH RESULTED IN A TOTAL LOSS OF ENGINE POWER. THE CORROSION WAS DUE TO THE MANUFACTURER'S PROCESS OF BRAZING THE METAL JOINT, AND THE CYCLIC LOADING WAS DUE TO THE ABSENCE OF A CLAMP TO MINIMIZE THE EFFECT OF VIBRATION. A CONTIBUTING FACTOR WAS THE LACK OF SUITABLE TERRAIN DURING THE SUBSEQUENT FORCED LANDING.
Source: NTSB Aviation Accident Database
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