19990903025609A

(.19) On September 3, 1999, about 1751 eastern daylight time, a Piper PA-18-135, N8143E, was substantially damaged during a forced landing after takeoff from the Aeroflex-Andover Airport (12N), Andover, new jersey. The certificated flight instructor (CFI) and passenger received minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the instructional flight conducted under 14 CFR part 91. The CFI departed 12N about 1700, and remained in the local area for an instructional flight. Approximately 20 minutes later he returned to the airport, landed, and kept the engine running while the student exited the airplane. A passenger was then boarded for an orientation flight. The CFI stated that he departed runway 21, and about 400 feet above the ground, the engine made "a metallic noise." The engine powered down and stopped with the propeller in a horizontal position. A 180 degree turn was made to land on runway 03. As the airplane approached the runway, the main wheels struck the bank of a pond approximately 100 feet short of the runway, the airplane nosed over, and the pilot and passenger exited the aircraft. The CFI observed fuel leaking from the aircraft and a small fire under the engine cowl. He extinguished the fire with dirt, flipped the airplane upright to stop fuel from leaking, closed the mixture, and turned the fuel and the magnetos to the off position. An examination of the engine on September 7, 1999, revealed a broken crankshaft at the crankshaft assembly near the number three cylinder. The camshaft was bent outward and a dent was observed at the point adjacent to the crankshaft break. Metal fragments and 1/3 of a valve lifter were found in the oil pan. Metal fragments were also found in the oil finger screen. All four cylinders and their pistons displayed no signs of visible damage. The crankshaft ring gear bolt was sheared and its mounting flange was bent. The crankshaft was retained for further examination. (-23)on 9/3/99, the aircraft departed on runway 21 at Andover, NJ (12N). During the climb, the pilot heard a metallic noise. The pilot immediately lowered the nose and turned the aircraft back to the runway (3). The engine and prop stopped. The aircraft hit the embankment at the end of the runway with the left wing and flipped. Inspection of the wreckage showed that t he rocker arms and 2 cylinders were not moving. Both occupants received minor injuries and have been released from the hospital. (.4) after takeoff, about 400 feet above the ground, the engine made 'a metallic noise.' The CFI initiated a turn back to the runway, and the engine powered down and stopped, with the propeller in a horizontal position. The main wheels of the airplane struck the bank of a pond approximately 100 feet short of the runway, the airplane nosed over, and the pilot and passenger exited the aircraft. Examination of the crankshaft revealed that the crankshaft was separated through the aft cheek of the #3 main bearing. Magnified visual examination of the fracture face found characteristics of fatigue propagation, which initiated in the aft radius of the #3 main bearing and progressed rearward through approximately 80% of the crankshaft cheek before failing in overload. Examination of the initiation area revealed a single origin on the surface of the radius in an area of circumferential scratches. The origin was located on the journal about 10 to 15 degrees before top center of the adjacent #2 and #3 cylinders.