Dunnellon, FL, USA
N6627U
BEECH 76
The private pilot and an examiner were conducting a practical examination flight in a multiengine airplane. The pilot stated that, after takeoff and about 100 ft above ground level, he raised the landing gear and heard a "thud"; seconds later, the airplane began an uncommanded turn to the right, consistent with a right engine failure. The examiner took control of the airplane and determined that it lacked the climb performance to clear the obstacles in its path. He then retarded the throttles and landed gear-up in the grass between the runway and hangars on the airport. During the landing, the left wing struck a concrete drain and was substantially damaged. Examination of the airplane revealed that the right engine single-drive dual magneto had separated from the accessory pad and was laying in the engine compartment. Because both magnetos were attached to the engine at a single point, the right engine lost power completely when this event occurred. The two nuts and clamps used to attach the magneto to the mounting studs were missing; the mounting studs appeared undamaged. Given this information, it is likely that the mounting nuts loosened over time, allowing the magneto to separate from the engine. The airplane's most recent 100-hour inspection was performed about 3 weeks (27 flight hours) before the accident. A required item of that inspection was to check studs and nuts for proper torqueing and obvious defects. Had the loose mounting nuts of the magneto been detected and corrected at this time, the magneto likely would not have separated from the engine.
On December 30, 2016, at 1010 eastern daylight time, a Beech 76, N6627U, was substantially damaged during a forced landing after takeoff from Marion County Airport (X35), Dunnellon, Florida. The private pilot and designated pilot examiner (DPE) were not injured. Visual meteorological conditions prevailed, and no flight plan was filed, for the instructional evaluation flight operated under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The flight was destined for the Crystal River Airport (CGC), Crystal River, Florida.According to the private pilot, the purpose of the flight was to conduct the practical test for his commercial pilot certificate, with a rating for airplane multiengine land. The flight departed CGC about 0945, conducted some navigation and maneuvering exercises, and landed at X35. The pilot then performed a normal takeoff with a simulated right engine failure at an altitude of 800 feet above ground level, followed by a single-engine landing to a full stop. Next, the pilot performed a short-field takeoff from runway 5, which was 5,000 feet long by 100 feet wide). About 100 feet above ground level, the pilot raised landing gear, heard a "thud," and seconds later the airplane began an "uncontrollable turn to the right much as one would expect from a right engine failure." The examiner took control of the airplane and determined it lacked the climb performance to clear the obstacles in its path. He then retarded the throttles and landed gear-up in the grass between the runway and the hangars on the east side of the airport. During the landing, the left wing struck a concrete drain and was substantially damaged. According to the examiner, he took control due to a "delay in maintaining directional control" by the pilot. The examiner held an airline transport pilot certificate with ratings for airplane single- and multiengine land, airplane single- and multiengine sea, and glider. He also held flight and ground instructor certificates. His most recent second-class medical certificate was issued on April 14, 2016, at which time he reported 24,600 total hours of flight experience. The pilot held a private pilot certificate with ratings for airplane single- and multiengine land, and instrument airplane. His most recent second-class medical certificate was issued on August 18, 2016. The pilot reported 2,100 total hours of flight experience. Examination of the airplane by a Federal Aviation Administration inspector revealed damage to the nose, propellers and fuselage belly. Flight control continuity was confirmed from each control surface to the cockpit controls. Examination of the right engine revealed that the single-drive dual magneto had separated from the accessory pad and was laying in the engine compartment. The two nuts and clamps used to attach the magneto to the mounting studs were missing. The mounting studs appeared undamaged. Review of the airplane's maintenance records revealed that the magneto was installed on December 10, 2014, about 466 flight hours prior to the accident. The most recent 100-hour inspection was performed on December 7, 2016, about 27 flight hours prior to the accident. Review of 14 CFR 41, Appendix D, Scope and Detail of Items (as applicable to the particular aircraft) to be Included in Annual and 100-hour Inspections revealed, "…(7) (2) Studs and nuts – for proper torqueing and obvious defects…" Review of engine failure after lift-off and in-flight information from an airplane make and model pilot operating handbook revealed, "An immediate landing is advisable regardless of take-off weight. Continued flight can not be assured if take-off weight exceeds the weight determined from the TAKE-OFF WEIGHT graph.
An inadequate 100-hour maintenance inspection that failed to detect and correct loose nuts on a single-drive dual magneto, which led to the subsequent separation of the magneto from the engine during initial climb and the total loss of engine power.
Source: NTSB Aviation Accident Database
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