659 

Federal Aviation Administration, DOT 

§ 29.1329 

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. 

§ 29.1329

Automatic pilot and flight 

guidance system. 

For the purpose of this subpart, an 

automatic pilot and flight guidance 
system may consist of an autopilot, 
flight director, or a component that 
interacts with stability augmentation 
or trim. 

(a) Each automatic pilot and flight 

guidance system must be designed so 
that it: 

(1) Can be overpowered by one pilot 

to allow control of the rotorcraft; 

(2) Provides a means to disengage the 

system, or any malfunctioning compo-
nent of the system, by each pilot to 
prevent it from interfering with the 
control of the rotorcraft; and 

(3) Provides a means to indicate to 

the flight crew its current mode of op-
eration. Selector switch position is not 
acceptable as a means of indication. 

(b) Unless there is automatic syn-

chronization, each system must have a 
means to readily indicate to the pilot 
the alignment of the actuating device 
in relation to the control system it op-
erates. 

(c) Each manually operated control 

for the system’s operation must be 
readily accessible to the pilots. 

(d) The system must be designed so 

that, within the range of adjustment 
available to the pilot, it cannot 
produce hazardous loads on the rotor-
craft, or create hazardous deviations in 
the flight path, under any flight condi-
tion appropriate to its use or in the 

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