# 14 CFR § 27.1325: Static pressure systems

> Federal · Regulations · In force

URL: https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1325

## Section

- **Citation:** 14 CFR § 27.1325
- **Heading:** Static pressure systems
- **Jurisdiction:** Federal
- **Kind:** Regulations
- **Status:** In force
- **Text as of:** September 22, 2026
- **Source:** Publisher's official text
- **Location:** Title 14—Aeronautics and Space > CHAPTER I—FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION > SUBCHAPTER C—AIRCRAFT > PART 27—AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT > Subpart F—Equipment > Instruments: Installation

## Text

(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 pressure in the static pressure system and true ambient atmospheric static pressure 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 the altimeter when on the primary static system by more than 50 feet, a correction card must be provided for the alternate static system.
(c) Except as provided in paragraph (d) 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.
(d) For unpressurized rotorcraft, paragraph (c)(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 Federal 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]

## Nearby sections

- [14 CFR § 27.1301 § 27.1301 Function and installation.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1301.md)
- [14 CFR § 27.1303 § 27.1303 Flight and navigation instruments.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1303.md)
- [14 CFR § 27.1305 § 27.1305 Powerplant instruments.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1305.md)
- [14 CFR § 27.1307 § 27.1307 Miscellaneous equipment.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1307.md)
- [14 CFR § 27.1309 § 27.1309 Equipment, systems, and installations.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1309.md)
- [14 CFR § 27.1316 § 27.1316 Electrical and electronic system lightning protection.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1316.md)
- [14 CFR § 27.1317 § 27.1317 High-intensity Radiated Fields (HIRF) Protection.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1317.md)
- [14 CFR § 27.1321 § 27.1321 Arrangement and visibility.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1321.md)
- [14 CFR § 27.1322 § 27.1322 Warning, caution, and advisory lights.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1322.md)
- [14 CFR § 27.1323 § 27.1323 Airspeed indicating system.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1323.md)
- [14 CFR § 27.1325 § 27.1325 Static pressure systems.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1325.md)
- [14 CFR § 27.1327 § 27.1327 Magnetic direction indicator.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1327.md)
- [14 CFR § 27.1329 § 27.1329 Automatic pilot and flight guidance system.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1329.md)
- [14 CFR § 27.1337 § 27.1337 Powerplant instruments.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1337.md)

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Source: Frix Law Library, https://www.frixlaw.com/law-library/statutes/ecfr-14-27.1325. Check the current official text before relying on it. Not legal advice.