spaschal on DSK3GDR082PROD with CFR

Section 25.481

14 CFR Ch. I (1-1-19 Edition)

from VL1 to 1.25 VL2 parallel to the
ground under the conditions prescribed
in Section 25.473 with - 
(1) VL1 equal to VS0 (TAS) at the appropriate landing weight and in standard sea level conditions; and
(2) VL2 equal to VS0 (TAS) at the appropriate landing weight and altitudes
in a hot day temperature of 41 degrees
F. above standard.
(3) The effects of increased contact
speed must be investigated if approval
of downwind landings exceeding 10
knots is requested.
(b) For the level landing attitude for
airplanes with tail wheels, the conditions specified in this section must be
investigated with the airplane horizontal reference line horizontal in accordance with Figure 2 of Appendix A
of this part.
(c) For the level landing attitude for
airplanes with nose wheels, shown in
Figure 2 of Appendix A of this part, the
conditions specified in this section
must be investigated assuming the following attitudes:
(1) An attitude in which the main
wheels are assumed to contact the
ground with the nose wheel just clear
of the ground; and
(2) If reasonably attainable at the
specified descent and forward velocities, an attitude in which the nose and
main wheels are assumed to contact
the ground simultaneously.
(d) In addition to the loading conditions prescribed in paragraph (a) of this
section, but with maximum vertical
ground reactions calculated from paragraph (a), the following apply:
(1) The landing gear and directly affected attaching structure must be designed for the maximum vertical
ground reaction combined with an aft
acting drag component of not less than
25% of this maximum vertical ground
reaction.
(2) The most severe combination of
loads that are likely to arise during a
lateral drift landing must be taken
into account. In absence of a more rational analysis of this condition, the
following must be investigated:
(i) A vertical load equal to 75% of the
maximum ground reaction of Section 25.473
must be considered in combination
with a drag and side load of 40% and
25% respectively of that vertical load.

(ii) The shock absorber and tire deflections must be assumed to be 75% of
the deflection corresponding to the
maximum
ground
reaction
of
Section 25.473(a)(2). This load case need not be
considered in combination with flat
tires.
(3) The combination of vertical and
drag components is considered to be
acting at the wheel axle centerline.
[Amdt. 25-91, 62 FR 40705, July 29, 1997; Amdt.
25-91, 62 FR 45481, Aug. 27, 1997]

Section 25.481

Tail-down landing conditions.

(a) In the tail-down attitude, the airplane is assumed to contact the ground
at forward velocity components, ranging from VL1 to VL2 parallel to the
ground under the conditions prescribed
in Section 25.473 with - 
(1) VL1 equal to VS0 (TAS) at the appropriate landing weight and in standard sea level conditions; and
(2) VL2 equal to VS0 (TAS) at the appropriate landing weight and altitudes
in a hot day temperature of 41 degrees
F. above standard.
(3) The combination of vertical and
drag components considered to be acting at the main wheel axle centerline.
(b) For the tail-down landing condition for airplanes with tail wheels, the
main and tail wheels are assumed to
contact the ground simultaneously, in
accordance with figure 3 of appendix A.
Ground reaction conditions on the tail
wheel are assumed to act - 
(1) Vertically; and
(2) Up and aft through the axle at 45
degrees to the ground line.
(c) For the tail-down landing condition for airplanes with nose wheels, the
airplane is assumed to be at an attitude corresponding to either the stalling angle or the maximum angle allowing clearance with the ground by each
part of the airplane other than the
main wheels, in accordance with figure
3 of appendix A, whichever is less.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-91, 62 FR 40705, July 29,
1997; Amdt. 25-94, 63 FR 8848, Feb. 23, 1998]

Section 25.483

One-gear landing conditions.

For the one-gear landing conditions,
the airplane is assumed to be in the
level attitude and to contact the
ground on one main landing gear, in

250

VerDate Sep<11>2014

12:50 Apr 30, 2019

Jkt 247046

PO 00000

Frm 00260

Fmt 8010

Sfmt 8010

Y:\SGML\247046.XXX

247046