Duk da haka, wani musamman tsanani high-gudun flutter matsala da aka warware kawai ta hanyar saka depleted uranium counterweights matsayin ballast a cikin outboard engine nacelles na farkon 747s. Wannan mataki ya sa tashin hankali a lokacin da wadannan jirgin sama ya fadi, misali El Al Flight 1862 a Amsterdam a 1992 tare da 282 kilogram (622 lb) na uranium a cikin tailplane (a kwance stabilizer). The jirgin gwajin shirin da aka hampered da matsaloli tare da 747 ta JT9D injuna.
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