Considerable conversation on this article and subject has taken place on Facebook and Oshkosh365 since Van’s
Aircraft posted this article on its Facebook
page in late June. Since then Greg Hale has
posted a response on his Web page. To read
Greg’s clarification and the responses on
Facebook and Oshkosh365, visit
www.SportAviation.org.
two-strap shoulder harness attached to a
hard point in the structural cabin top.
We used the two-strap (one over each
shoulder) harness because it is the
universal aircraft standard and has been
demonstrated to be superior to the
automotive-style single cross-strap.
Anchoring the harness to a hard point in
the cabin top provides a near ideal load
path for crash restraint forces. (See
Illustration 1.)
The subject airplane uses a single
cross shoulder harness anchored to a
hard point in the fuselage under and aft
of the seat. The strength of the anchor
point is somewhat irrelevant in this
installation, because the load path
essentially applies the crash loads to the
top of the seat back. (See Illustration 2.)
The low anchor point for the shoulder
harness causes the tension in the strap to
bear down on the occupant’s spine, and to
pull forward on the top of the seat back.
The back of the Oregon Aero seat
supplied in the RV- 10 kit was not
designed to withstand shoulder harness
crash impact acceleration forces. When
the seat back fails, the upper body will
pitch forward because the shoulder
harness essentially becomes slack. While
some automotive seats do apply the
shoulder harness loads to the top of the
seat backs, we assume that those heavy
automotive seats have been adequately
designed and tested for this purpose. The
RV- 10 seats have been designed and
tested by Oregon Aero Inc. to withstand
anticipated crash impact loads of the
occupant, but not acceleration loads
transmitted through shoulder harnesses.
