The FAR-25.725 assumes a Lift-to-Weight-Ratio L/W = 1 for the landing gear drop test while the FAR-23.725 assumes only L/W=0.667. This factor affects the load inertia factor n which is also needed for structural analysis. Does anybody have an explanation for the lower assumed Lift-to-Weight-Ratio for smaller aircraft?

  • $\begingroup$ It's most likely one of these things that make Part 23 easier to certify than Part 25 (because the intended product carries fewer people). Plenty of these examples in S&C/perf/loads. $\endgroup$
    – JZYL
    Aug 17 '20 at 17:06
  • $\begingroup$ Thanks for your comment. I totally agree with it. However, I think there is also a physical explanation, why heavier aircraft have a lower load inertia factor. Even if you stay in the range of the FAR-23 design code it seems common engineer knowledge that the lift-to-weight-ratio increases (and the inertia load factor decreases) with the weight. Even after long research, I couldn't find any explanation. $\endgroup$
    – Paul G
    Aug 17 '20 at 17:22
  • $\begingroup$ Ah ok, in this case it would appear to be opposite. I believe it has something to do with Part 25 operators are professionals, whereas most Part 23 are general community (commuter category aside). It's the same thing with stall demo: Part 23 requires pulling all the way to full stop (or uncontrollable ND), whereas Part 25 only requires going till distinctive ND occurs. But this is slightly different in that this is specified through AC, not the reg. $\endgroup$
    – JZYL
    Aug 17 '20 at 18:15

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