Aircraft Instrument Systems
Aircraft Instrument Systems is a core knowledge area on the AMT — Airframe FAA written exam. This hub collects our 15 in-depth, ACS-aligned aircraft instrument systems articles — each written in plain English and grounded in the official FAA handbooks. Work through them below, then drill the topic with practice questions.
Pitot-Static System Components and Plumbing
The pitot-static system feeds airspeed, altitude, and vertical-speed instruments by capturing impact and static air pressure; understanding its components, plumbing, and failure modes is essential for airframe technicians and pilots alike.
Altimeter Calibration and Scale Error
Altimeter calibration ensures accurate altitude readouts by correcting scale and mechanical errors; AMT airframe technicians must understand calibration standards, error sources, and inspection requirements.
Attitude Gyroscope Erection Systems
Attitude gyroscopes rely on erection systems to keep the gyro rotor aligned with true vertical, correcting precession-induced drift and ensuring accurate pitch-and-bank information at all times.
Vertical Speed Indicator Operating Principles
The vertical speed indicator (VSI) uses a calibrated leak to sense the rate of change in static pressure, giving pilots a clear indication of climb or descent rate in feet per minute.
Pitot Heat Circuit Inspection and Testing
Pitot heat systems prevent ice blockage of the pitot tube—a blockage that can cause catastrophic airspeed indication errors. Learn how the circuit works, how to inspect and test it, and what the FAA expects you to know.
Directional Gyroscope Precession and Drift Correction
The directional gyroscope provides a stable heading reference but accumulates drift from mechanical friction and Earth's rotation, requiring periodic realignment to the magnetic compass.
Vacuum System Pumps and Relief Valves
Vacuum system pumps and relief valves are the heart of gyroscopic instrument power on many light aircraft, providing the regulated suction needed to spin attitude and heading indicators reliably.
Static Port Alternate Air Source Operation
The static port provides reference pressure for altimeters, airspeed indicators, and VSIs; when it ices over or blocks, an alternate static source restores accurate readings with predictable instrument errors.
Instrument Panel Shock Mounting Requirements
Shock mounting systems protect sensitive flight instruments from vibration and impact damage; AMTs must understand the design requirements, inspection criteria, and regulatory standards governing proper installation.
Turn Coordinator vs Turn-and-Slip Indicator Differences
The turn coordinator and turn-and-slip indicator both display yaw and coordination data, but differ fundamentally in gyro orientation, what they sense, and how they display turning information.
Encoding Altimeter and Mode C Transponder Interface
The encoding altimeter converts barometric altitude into a Gray code signal that feeds Mode C transponder, allowing ATC to display pressure altitude alongside radar returns for traffic separation and collision avoidance.
Instrument Static System Leak Testing Procedures
A static system leak test verifies the airtight integrity of the pitot-static plumbing, ensuring accurate airspeed, altitude, and VSI readings; FAA regulations mandate testing after certain repairs or alterations.
Angle of Attack Indicator System Installation
An angle of attack indicator system measures the actual aerodynamic angle between the wing chord line and the relative wind, providing stall margin awareness independent of airspeed, weight, or bank angle.
Glass Cockpit Primary Flight Display Redundancy Requirements
Modern glass cockpit Primary Flight Displays must meet strict FAA redundancy requirements so that no single failure leaves a crew without essential flight information; understanding these layered backup systems is critical for airframe technicians.
Magnetic Compass Deviation and Compensation Card
Magnetic compass deviation arises from aircraft-generated magnetic fields that distort compass readings; technicians correct it through a compensation procedure and document residual errors on a deviation card.
More AMT — Airframe subjects
Articles are original summaries grounded in the public-domain FAA handbooks and cite their source. ACS-aligned study aids — not a substitute for the official handbooks or regulations.