MEDINA, OH, USA
N39945
Piper PA-32RT-300T
After take-off, the pilot heard the engine "pop" followed by a loss of engine power, which resulted in a forced landing into trees. Examination of the engine revealed that a newly installed factory remanufactured single-drive dual magneto had separated from the engine. It had accumulated 17.9 hours at the time of the accident. Examination of the magneto and the installed clamping blocks revealed that the mounting flanges on both sides of the distributor housing exhibited fatigue beach marks. Examination of the mounting flanges also revealed that there were two sets of contact marks. The smaller more linear inboard set of marks matched the contour of the installed magneto clamping blocks when tilted slightly. These marks only penetrated slightly into the surface of the flanges. The installed clamping blocks appeared to meet the shape and dimensional requirements of older style clamping blocks issued by the engine manufacturer. The other marks were wider with curved ends that did not match any feature of the older style installed clamping blocks. A small step was apparent at the edge of the larger contact area indicating removal or displacement of material from the surface. The marks did however appear to match the configuration and shape for newer style clamping blocks introduced by the engine manufacturer on engines produced after March 1985. According to the engine manufacturer, the change was instituted as a production product improvement and the use of the newer clamping blocks was not a mandatory requirement on the engine installed in this airplane. According to the magneto manufacturer, the magneto housings are stripped of paint and dipped into a dichromate bath for corrosion prevention during the remanufacturing process. They were subjected to an inspection for cracks, but the inspection was only visual. .
On September 25, 2001, at 1420 eastern daylight time, a Piper PA-32RT-300T, N39945, was substantially damaged during a forced landing after take-off from Medina Municipal Airport (1G5), Medina, Ohio. The certificated commercial pilot sustained serious injuries. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight conducted under 14 CFR Part 91. The pilot was interviewed shortly after the accident by an Ohio State Highway Patrol trooper. According to the trooper's report, the pilot performed a pre-flight inspection and had 60-gallons of fuel onboard. Prior to take-off, he performed an engine run-up, and "everything seemed fine." The pilot said that shortly after take-off, the engine "popped" then "quit." He also observed smoke coming from the left side of the engine. A witness observed the airplane taking off on the east-west runway. In a written statement, he reported that the airplane was "too low" and he heard it impact the ground. An Ohio State Highway Patrol trooper asked the witness if he could hear the airplane's engine running. The witness responded, "No, it appeared to be gliding downward." A Federal Aviation Administration (FAA) inspector performed an on-scene examination. According to the inspector, the airplane collided with a small tree, impacted the bank of a small pond, then skidded upright about 40 feet. Examination of the airplane revealed that the landing gear and both wings were damaged, and both wing fuel tanks were breached. One propeller blade appeared to be straight and the other two blades were curled aft under the engine. On October 4, 2001, two FAA inspectors and a representative of the engine manufacturer performed an examination of the engine. According to an inspector, the dual magneto was found separated from the engine. Examination of airplane records revealed that the factory remanufactured dual magneto was installed on the airplane on May 11, 2001, and had accumulated 17.9 hours of service at the time of the accident. The magneto and associated clamping blocks were examined at the Safety Board's Materials Laboratory in Washington, DC. The mounting flanges on both sides of the distributor housing were fractured. According to the metallurgist's factual report, initial optical examinations revealed fatigue beach marks that covered the majority of the fractured surfaces. The fatigue on both fractures initiated on the surfaces of the fillet between the flanges and the exposed body of the housing. One end exhibited two fatigue origins, and the other end exhibited one. No damage was noted at the fatigue origins. From the initiation sites, the fatigue progressed inward on approximate 45 degree planes toward the impulse coupling. The fractured surfaces were degreased, and the end with two fatigue signatures exhibited a darkened appearance and yellow tint. The area that exhibited the yellow tint was more diffuse and located toward the origin area, while the darker areas were further away and ended at distinct lines near the terminus of the fatigue region. The other end also exhibited the diffuse yellow tint near the fatigue origin areas, but not near the darkened areas. Examination of the mounting flanges revealed that there were two sets of contact marks. According to the metallurgist’s factual report: "The smaller more linear inboard set of marks matched the contour of the received magneto clamps when tilted slightly. These marks only penetrated slightly into the surface of the flanges. The received clamps appeared to meet the shape and dimensional requirements of part number LW-18378 clamps. The other marks were wider with curved ends that did not match any feature of the received blocks. The marks did however appear to match the configuration and shape for part number 66M19385 clamps. A small step was apparent at the edge of the larger contact area indicating removal or displacement of material from the surface. "According to Lycoming, part number 66M19385 clamps are newer and replace part number LW-18378 clamps on engines produced since March 18, 1985. The change was instituted as a production product improvement and is not a mandatory requirement on the TIO-540 installed in this aircraft." According to the magneto manufacturer, magneto housings are stripped of paint and dipped into a dichromate bath for corrosion prevention during the magneto remanufacturing process. They are also subjected to an inspection for cracks, but the inspection is only visual. Weather at Wayne County Airport (BJJ), Wooster, Ohio, at 1353, included wind from 260 degrees at 11 knots and visibility 10 miles. .
fatigue failure of the dual magneto mounting flanges that resulted from undetected contact damage sustained during a previous installation, which resulted in its separation from the engine during take-off.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
