658 

14 CFR Ch. I (1–1–19 Edition) 

§ 29.1325 

(c) For Category A rotorcraft— 
(1) The indication must allow con-

sistent definition of the takeoff deci-
sion point; and 

(2) The system error, excluding the 

airspeed instrument calibration error, 
may not exceed— 

(i) Three percent or 5 knots, which-

ever is greater, in level flight at speeds 
above 80 percent of takeoff safety 
speed; and 

(ii) Ten knots in climb at speeds from 

10 knots below takeoff safety speed to 
10 knots above V

Y

. 

(d) For Category B rotorcraft, the 

system error, excluding the airspeed 
instrument calibration error, may not 
exceed 3 percent or 5 knots, whichever 
is greater, in level flight at speeds 
above 80 percent of the climbout speed 
attained at 50 feet when complying 
with § 29.63. 

(e) Each system must be arranged, so 

far as practicable, to prevent malfunc-
tion or serious error due to the entry of 
moisture, dirt, or other substances. 

(f) Each system must have a heated 

pitot tube or an equivalent means of 
preventing malfunction due to icing. 

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as 
amended by Amdt. 29–3, 33 FR 970, Jan. 26, 
1968; Amdt. 29–24, 49 FR 44439, Nov. 6, 1984; 
Amdt. 29–39, 61 FR 21901, May 10, 1996; Amdt. 
29–44, 64 FR 45338, Aug. 19, 1999] 

§ 29.1325

Static pressure and pressure 

altimeter systems. 

(a) Each instrument with static air 

case connections must be vented to the 
outside atmosphere through an appro-
priate piping system. 

(b) Each vent must be located where 

its orifices are least affected by airflow 
variation, moisture, or foreign matter. 

(c) 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 
the alternate static pressure system, 
differs from the reading of altimeter 
when on the primary static system by 
more than 50 feet, a correction card 

must be provided for the alternate 
static system. 

(d) Except for the vent into the at-

mosphere, each system must be air-
tight. 

(e) Each pressure altimeter must be 

approved and calibrated to indicate 
pressure altitude in a standard atmos-
phere with a minimum practicable 
calibration error when the cor-
responding static pressures are applied. 

(f) Each system must be designed and 

installed so that an error in indicated 
pressure altitude, at sea level, with a 
standard atmosphere, excluding instru-
ment calibration error, does not result 
in an error of more than 

±

30 feet per 100 

knots speed. However, the error need 
not be less than 

±

30 feet. 

(g) Except as provided in paragraph 

(h) of this section, if the static pressure 
system incorporates both a primary 
and an alternate static pressure source, 
the means for selecting one or the 
other source must be designed so 
that— 

(1) When either source is selected, the 

other is blocked off; and 

(2) Both sources cannot be blocked 

off simultaneously. 

(h) For unpressurized rotorcraft, 

paragraph (g)(1) of this section does not 
apply if it can be demonstrated that 
the static pressure system calibration, 
when either static pressure source is 
selected, is not changed by the other 
static pressure source being open or 
blocked. 

(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), Dept. 
of Transportation Act (49 U.S.C. 1655(c))) 

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as 
amended by Amdt. 29–14, 42 FR 36972, July 18, 
1977; Amdt. 29–24, 49 FR 44439, Nov. 6, 1984] 

§ 29.1327

Magnetic direction indicator. 

(a) Each magnetic direction indicator 

must be installed so that its accuracy 
is not excessively affected by the 
rotorcraft’s vibration or magnetic 
fields. 

(b) The compensated installation 

may not have a deviation, in level 
flight, greater than 10 degrees on any 
heading. 

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