549 

Federal Aviation Administration, DOT 

§ 27.1325 

prevent the continued safe flight and 
landing of a rotorcraft 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 44026, Aug. 6, 
2007] 

I

NSTRUMENTS

: I

NSTALLATION

 

§ 27.1321

Arrangement and visibility. 

(a) Each flight, navigation, and pow-

erplant instrument for use by any pilot 
must be easily visible to him. 

(b) For each multiengine rotorcraft, 

identical powerplant instruments must 
be located so as to prevent confusion as 
to which engine each instrument re-
lates. 

(c) Instrument panel vibration may 

not damage, or impair the readability 
or accuracy of, any instrument. 

(d) If a visual indicator is provided to 

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

(Secs. 313(a), 601, 603, 604, and 605 of the Fed-
eral Aviation Act of 1958 (49 U.S.C. 1354(a), 
1421, 1423, 1424, and 1425); and sec. 6(c) of the 
Dept. of Transportation Act (49 U.S.C. 
1655(c))) 

[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964; 29 
FR 17885, Dec. 17, 1964, as amended by Amdt. 
27–13, 42 FR 36971, July 18, 1977] 

§ 27.1322

Warning, caution, and advi-

sory lights. 

If warning, caution or advisory lights 

are installed in the cockpit, they must, 
unless otherwise approved by the Ad-
ministrator, be— 

(a) Red, for warning lights (lights in-

dicating a hazard which may require 
immediate corrective action): 

(b) Amber, for caution lights (lights 

indicating the possible need for future 
corrective action); 

(c) Green, for safe operation lights; 

and 

(d) Any other color, including white, 

for lights not described in paragraphs 
(a) through (c) of this section, provided 
the color differs sufficiently from the 
colors prescribed in paragraphs (a) 
through (c) of this section to avoid pos-
sible confusion. 

[Amdt. 27–11, 41 FR 55470, Dec. 20, 1976] 

§ 27.1323

Airspeed indicating system. 

(a) Each airspeed indicating instru-

ment must be calibrated to indicate 
true airspeed (at sea level with a stand-
ard atmosphere) with a minimum prac-
ticable instrument calibration error 
when the corresponding pitot and stat-
ic pressures are applied. 

(b) The airspeed indicating system 

must be calibrated in flight at forward 
speeds of 20 knots and over. 

(c) At each forward speed above 80 

percent of the climbout speed, the air-
speed indicator must indicate true air-
speed, at sea level with a standard at-
mosphere, to within an allowable in-
stallation error of not more than the 
greater of— 

(1) 

±

3 percent of the calibrated air-

speed; or 

(2) Five knots. 

(Secs. 313(a), 601, 603, 604, and 605 of the Fed-
eral Aviation Act of 1958 (49 U.S.C. 1354(a), 
1421, 1423, 1424, and 1425); and sec. 6(c) of the 
Dept. of Transportation Act (49 U.S.C. 
1655(c))) 

[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as 
amended by Amdt. 27–13, 42 FR 36972, July 18, 
1977] 

§ 27.1325

Static pressure systems. 

(a) Each instrument with static air 

case connections must be vented so 
that the influence of rotorcraft speed, 
the opening and closing of windows, 
airflow variation, and moisture or 
other foreign matter does not seriously 
affect its accuracy. 

(b) Each static pressure port must be 

designed and located in such manner 
that the correlation between air pres-
sure in the static pressure system and 
true ambient atmospheric static pres-
sure is not altered when the rotorcraft 
encounters icing conditions. An anti- 
icing means or an alternate source of 
static pressure may be used in showing 
compliance with this requirement. If 
the reading of the altimeter, when on 

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