hgmckay
Joined: 23 May 2006
Posts: 397
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 Posted: Sat May 27, 2006 12:42 pm Post subject: Cracks in Main Landing Gear Legs of Thom Riddle's Allegro |
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Guys:
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I have looked at the photos sent by Thom and based on my knowledge (as a structural engineer) of the flexing mechanism of the legs during landings (hard or soft), the top portion of the legs at the point where the cracks are located are put into compression upon impact of the wheels with the landing surface (i.e. the legs flex outward putting the top surface of the gear where the cracks are located in compression while the bottom surface is put in tension). From the photographs the cracks look like classical fatigue failure of FRP (Fiberglass Reinforced Plastic) material. The cracks appear to be transverse cracks across the laminations, which is a classical failure due to cyclic stress, even though I cannot fathom the number of landings it would take to do this unless they were landings that were over stressing the material each time.
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I admit that I have not actually examined the legs or the cracks, but that is what it appears to be. Thom, I would suggest you have the damage legs examined by an expert in forensic analysis to give you a better professional opinion of why the failure cracks are appearing. This may indeed be a design flaw, or the result of severe landing impacts. Does anyone know if Fantasy Air did cyclic loading of the landing gear, or just a static load test. If you return the legs to Fantasy Air USA, I assure you, you will get no meaningful answers from them.
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Hugh McKay
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