not be detected initially. So an additional suggestion would have been the use of a possible Ultrasonic Testing (UT) inspection. This technique uses sound waves to detect cracks in materials, and would help investigators produce images deeper than the surface of the components, this includes the bolts, the hold-down nuts, the cylinder head, and the crankcase (Element, n.d.).FindingsFocusing on the findings that relate to the reciprocating engine of the aircraft, the aforementioned information retrieved by the metallurgical inspection, optical examination, and SEM analysis, aided the NTSB to provide sound findings. This, in specific, was that the two or more hold-down nuts of the right engine No. 2 cylinder which had backed off and loosened,
PROJECT 1: AIR SUNSHINE FLIGHT 52715resulted in the fracturing of the remaining bolts, nuts and studs because of high-stress fatigue (NTSB, 2004). Therefore, with the unfastened and compromised structural integrity of the bolts and studs, this ultimately led to the cylinder being detached from the engine and the engine failing in-flight.But as reported after the completion of the multiple investigative techniques, NTSB investigators stated that the likelihood of a simultaneous occurrence of two or more nuts loosening, is slim to none, only if maintenance procedures were adhered to (NTSB, 2004). This led the investigators to review other external influences, most notably the maintenance records, and branch out to human factors, not just the construction and design of the engine. Hence, with the full review of Air Sunshine’s maintenance records, blatant deviations related to corrective maintenance to the right engine’s cylinder assembly and repeated checks, were found. This finalizes the NTSB findings, whereby the improperly fastened hold-down nuts of the No.2 cylinder were a result of inadequate torque applied when installing the components (NTSB, 2004).CausesTherefore, mechanically speaking, through the detailed findings it was deduced that the probable cause was due to the insufficient adherence and performance of the airline’s proprietarytechnicians to carry out the maintenance procedures given to them for the accident aircraft and engine involved, during undocumented maintenance (NTSB, 2004). Contributing to this accidentwas the pilot’s failure to safely fly the aircraft with diminished performance levels, as the Cessna402C was designed to operate and continue to fly with just one fully-operational engine (NTSB, 2004).
PROJECT 1: AIR SUNSHINE FLIGHT 52716NTSB recommendations to prevent similar accidents in the futureAs a result of the investigation, NTSB suggested the following recommendation: Issue a flight standards information bulletin to principal operations inspectors of all Part 135 single-pilot operators that carry passengers and operate over water, which familiarizes them with the circumstances of the Air Sunshine flight 527 accident and emphasizes the need for pilots to provide timely emergency briefings. The bulletin should