Code of Federal Regulations - Title 14

499

Federal Aviation Administration, DOT

§ 25.1322

airplane is exposed to HIRF environ-
ment II, as described in appendix L to
this part.

(b) Each electrical and electronic

system that performs a function whose
failure would significantly reduce the
capability of the airplane or the ability
of the flightcrew to respond to an ad-
verse operating condition must be de-
signed and installed so the system is
not adversely affected when the equip-
ment providing these functions is ex-
posed to equipment HIRF test level 1
or 2, as described in appendix L to this
part.

tem that performs a function whose
failure would reduce the capability of
the airplane or the ability of the
flightcrew to respond to an adverse op-
erating condition must be designed and
installed so the system is not adversely
affected when the equipment providing
the function is exposed to equipment
HIRF test level 3, as described in ap-
pendix L to this part.

(d) Before December 1, 2012, an elec-

trical or electronic system that per-
forms a function whose failure would
prevent the continued safe flight and
landing of an airplane may be designed
and installed without meeting the pro-
visions of paragraph (a) provided—

(1) The system has previously been

shown to comply with special condi-
tions for HIRF, prescribed under § 21.16,
issued before December 1, 2007;

(2) The HIRF immunity characteris-

tics of the system have not changed
since compliance with the special con-
ditions was demonstrated; and

(3) The data used to demonstrate

compliance with the special conditions
is provided.

[Doc. No. FAA–2006–23657, 72 FR 44025, Aug. 6,
2007]

NSTRUMENTS

: I

NSTALLATION

§ 25.1321

Arrangement and visibility.

(a) Each flight, navigation, and pow-

erplant instrument for use by any pilot
must be plainly visible to him from his
station with the minimum practicable
deviation from his normal position and
line of vision when he is looking for-
ward along the flight path.

(b) The flight instruments required

by § 25.1303 must be grouped on the in-

strument panel and centered as nearly
as practicable about the vertical plane
of the pilot’s forward vision. In addi-
tion—

(1) The instrument that most effec-

tively indicates attitude must be on
the panel in the top center position;

(2) The instrument that most effec-

tively indicates airspeed must be adja-
cent to and directly to the left of the
instrument in the top center position:

(3) The instrument that most effec-

tively indicates altitude must be adja-
cent to and directly to the right of the
instrument in the top center position;
and

(4) The instrument that most effec-

tively indicates direction of flight
must be adjacent to and directly below
the instrument in the top center posi-
tion.

must be closely grouped on the instru-
ment panel. In addition—

(1) The location of identical power-

plant instruments for the engines must
prevent confusion as to which engine
each instrument relates; and

(2) Powerplant instruments vital to

the safe operation of the airplane must
be plainly visible to the appropriate
crewmembers.

(d) Instrument panel vibration may

not damage or impair the accuracy of
any instrument.

(e) If a visual indicator is provided to

indicate malfunction of an instrument,
it must be effective under all probable
cockpit lighting conditions.

[Amdt. 25–23, 35 FR 5679, Apr. 8, 1970, as
amended by Amdt. 25–41, 42 FR 36970, July 18,
1977]

§ 25.1322

Flightcrew alerting.

(a) Flightcrew alerts must:
(1) Provide the flightcrew with the

information needed to:

(i) Identify non-normal operation or

airplane system conditions, and

(ii) Determine the appropriate ac-

tions, if any.

(2) Be readily and easily detectable

and intelligible by the flightcrew under
all foreseeable operating conditions,
including conditions where multiple
alerts are provided.

(3) Be removed when the alerting

condition no longer exists.

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