(S (S (SBAR (IN Although) (S (BASENP (NNS authorities)) (VP (VBD released) (BASENP (DT no) (NN crash) (NNS details))))) (COMMA ,) (S (BASENP (NNS witnesses)) (VP (VBP say) (SBAR (S (BASENP (DT the) (NN helicopter)) (VP (VP (VBD lost) (BASENP (NN power))) (PP (IN during) (NP (NNS attempts) (S (VP (TO to) (VP (VB land)))))))))))) (PERIOD .))