spaschal on DSK3GDR082PROD with CFR

Section 25.1331

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

from providing guidance or control to
an unsafe speed.
(i) The flight guidance system functions, controls, indications, and alerts
must
be
designed
to
minimize
flightcrew errors and confusion concerning the behavior and operation of
the flight guidance system. Means
must be provided to indicate the current mode of operation, including any
armed modes, transitions, and reversions. Selector switch position is not
an acceptable means of indication. The
controls and indications must be
grouped and presented in a logical and
consistent manner. The indications
must be visible to each pilot under all
expected lighting conditions.
(j) Following disengagement of the
autopilot, a warning (visual and auditory) must be provided to each pilot
and be timely and distinct from all
other cockpit warnings.
(k) Following disengagement of the
autothrust function, a caution must be
provided to each pilot.
(l) The autopilot may not create a
potential hazard when the flightcrew
applies an override force to the flight
controls.
(m) During autothrust operation, it
must be possible for the flightcrew to
move the thrust levers without requiring excessive force. The autothrust
may not create a potential hazard
when the flightcrew applies an override
force to the thrust levers.
(n) For purposes of this section, a
transient is a disturbance in the control or flight path of the airplane that
is not consistent with response to
flightcrew inputs or environmental
conditions.
(1) A minor transient would not significantly reduce safety margins and
would involve flightcrew actions that
are well within their capabilities. A
minor transient may involve a slight
increase in flightcrew workload or
some physical discomfort to passengers
or cabin crew.
(2) A significant transient may lead
to a significant reduction in safety
margins, an increase in flightcrew
workload, discomfort to the flightcrew,
or physical distress to the passengers
or cabin crew, possibly including nonfatal injuries. Significant transients do
not require, in order to remain within

or recover to the normal flight envelope, any of the following:
(i) Exceptional piloting skill, alertness, or strength.
(ii) Forces applied by the pilot which
are greater than those specified in
Section 25.143(c).
(iii) Accelerations or attitudes in the
airplane that might result in further
hazard to secured or non-secured occupants.
[Doc. No. FAA-2004-18775, 71 FR 18191, Apr.
11, 2006]

Section 25.1331 Instruments using a power
supply.
(a) For each instrument required by
Section 25.1303(b) that uses a power supply,
the following apply:
(1) Each instrument must have a visual means integral with, the instrument, to indicate when power adequate
to sustain proper instrument performance is not being supplied. The power
must be measured at or near the point
where it enters the instruments. For
electric instruments, the power is considered to be adequate when the voltage is within approved limits.
(2) Each instrument must, in the
event of the failure of one power
source, be supplied by another power
source. This may be accomplished
automatically or by manual means.
(3) If an instrument presenting navigation data receives information from
sources external to that instrument
and loss of that information would
render the presented data unreliable,
the instrument must incorporate a visual means to warn the crew, when such
loss of information occurs, that the
presented data should not be relied
upon.
(b) As used in this section,  - instrument -  includes devices that are physically contained in one unit, and devices that are composed of two or more
physically separate units or components connected together (such as a remote indicating gyroscopic direction
indicator that includes a magnetic
sensing element, a gyroscopic unit, an
amplifier and an indicator connected
together).
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-41, 42 FR 36970, July 18,
1977]

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