> Be aware that the use of a third pin in the door frame midway along weakens
> the airframe structure significantly. I only found this out in discussion
> with the PFA reference modifications in general. In their opinion this is a
> strength critical area and they would not approve any such mod for UK
> aircraft. Apparantly it would greatly affect the crashworthyness of the
> side of the fuselage.
>
> Nigel Charles
I assume that conclusion was reached without documented engineering
analysis of the strucure itself, then in various crash scenarios. A
good engineer can eyeball something to a reasonable conclusion, but
that same engineer should be able to then "thumbnail" how much glass
reinforcement goes underneath the little hole in the door sill to
return strength, no?
Since structural crashworthiness has never been required of
U.S.-certificated aircraft, commuter category and below, little may be
known unless other countries have so required. NASA here has thus
crashed small planes for research, and it was only about 2 years they
did so with composite fuselages, as they say composites behave
differently. NASA should have just talked to PFA!
Regards,
Fred F.
N3EU
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