29.501—Ground loading conditions: landing gear with skids.
(a) General.
Rotorcraft with landing gear with skids must be designed for the loading conditions specified in this section. In showing compliance with this section, the following apply:
(1)
The design maximum weight, center of gravity, and load factor must be determined under §§ 29.471 through 29.475.
(3)
Design ultimate loads for elastic spring members need not exceed those obtained in a drop test of the gear with—
(ii)
An assumed rotor lift of not more than 1.5 times that used in the limit drop tests prescribed in § 29.725.
(i)
The gear in its most critically deflected position for the landing condition being considered; and
(b) Vertical reactions in the level landing attitude.
In the level attitude, and with the rotorcraft contacting the ground along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section.
(c) Drag reactions in the level landing attitude.
In the level attitude, and with the rotorcraft contacting the ground along the bottom of both skids, the following apply:
(1)
The vertical reactions must be combined with horizontal drag reactions of 50 percent of the vertical reaction applied at the ground.
(2)
The resultant ground loads must equal the vertical load specified in paragraph (b) of this section.
(d) Sideloads in the level landing attitude.
In the level attitude, and with the rotorcraft contacting the ground along the bottom of both skids, the following apply:
(i)
Equal to the vertical loads obtained in the condition specified in paragraph (b) of this section; and
(2)
The vertical ground reactions must be combined with a horizontal sideload of 25 percent of their value.
(e) One-skid landing loads in the level attitude.
In the level attitude, and with the rotorcraft contacting the ground along the bottom of one skid only, the following apply:
(1)
The vertical load on the ground contact side must be the same as that obtained on that side in the condition specified in paragraph (b) of this section.
(f) Special conditions.
In addition to the conditions specified in paragraphs (b) and (c) of this section, the rotorcraft must be designed for the following ground reactions:
(1)
A ground reaction load acting up and aft at an angle of 45 degrees to the longitudinal axis of the rotorcraft. This load must be—
(2)
With the rotorcraft in the level landing attitude, a vertical ground reaction load equal to one-half of the vertical load determined under paragraph (b) of this section. This load must be—
(ii)
Distributed equally over 33.3 percent of the length between the skid tube attachments and centrally located midway between the skid tube attachments.