Sec. 25.775 - Windshields and windows.
(a) Internal panes must be made of
(b) Windshield panes directly in front
of the pilots in the normal conduct of their duties, and the supporting
structures for these panes, must withstand, without penetration, the
impact of a four-pound bird when the velocity of the airplane (relative to
the bird along the airplane's flight path) is equal to the value of VC,
at sea level, selected under §25.335(a).
(c) Unless it can be shown by analysis
or tests that the probability of occurrence of a critical windshield
fragmentation condition is of a low order, the airplane must have a means
to minimize the danger to the pilots from flying windshield fragments due
to bird impact. This must be shown for each transparent pane in the
cockpit that --
(1) Appears in the front view of the
(2) Is inclined 15 degrees or more to
the longitudinal axis of the airplane; and
(3) Has any part of the pane located
where its fragmentation will constitute a hazard to the pilots.
(d) The design of windshields and
windows in pressurized airplanes must be based on factors peculiar to high
altitude operation, including the effects of continuous and cyclic
pressurization loadings, the inherent characteristics of the material
used, and the effects of temperatures and temperature differentials. The
windshield and window panels must be capable of withstanding the maximum
cabin pressure differential loads combined with critical aerodynamic
pressure and temperature effects after any single failure in the
installation or associated systems. It may be assumed that, after a single
failure that is obvious to the flight crew (established under §25.1523),
the cabin pressure differential is reduced from the maximum, in accordance
with appropriate operating limitations, to allow continued safe flight of
the airplane with a cabin pressure altitude of not more than 15,000 feet.
(e) The windshield panels in front of
the pilots must be arranged so that, assuming the loss of vision through
any one panel, one or more panels remain available for use by a pilot
seated at a pilot station to permit continued safe flight and landing.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-23, 35 FR 5676, Apr. 8, 1970; Amdt. 25-38, 41 FR
55466, Dec. 20, 1976]