KZSP

KZSP airspeed corrector-setter on Mi-8 helicopters

The KZSP is an aircraft airspeed corrector-setter used on Mi-8, Mi-8T, Mi-8MTV, Mi-171 and related helicopter versions, depending on installed equipment. It belongs to the flight and navigation equipment group and works with air data sources, automatic control systems and autopilot equipment such as AP-34B. The unit is used when the helicopter system must compare the current indicated airspeed with a selected value and generate signals for speed stabilization or control logic. KZSP is not a simple cockpit speed indicator; it is a signal-forming and correction unit.

Speed setting and stabilization through KZSP

One of the main functions of the KZSP is to let the required indicated airspeed be set and then compare it with the actual airspeed signal. When the helicopter deviates from the selected value, the unit forms a mismatch signal that can be used by the autopilot or related control circuits. This makes the device important for automatic speed stabilization modes. The pilot or system sets the required speed, while the KZSP follows the airspeed input and provides an electrical output proportional to the difference between the actual and selected speed.

KZSP with AP-34B autopilot equipment

On Mi-8-family helicopters, the KZSP can work in the circuit of the AP-34B autopilot and related flight control equipment. Its signals may be used together with other autopilot inputs, including attitude, angular rate, altitude and air data channels. If the KZSP does not operate correctly, the helicopter may fail to hold the selected speed, or the automatic control system may receive an incorrect mismatch signal. For troubleshooting, the unit should be checked together with the air pressure lines, power supply, connector, autopilot circuits and associated readiness / failure signal blocks.

Pressure input and sensing principle of KZSP

The KZSP uses air pressure data from the aircraft pitot-static system. The unit is connected to static pressure and total / dynamic pressure lines, and its internal pressure-sensitive element reacts to the pressure difference corresponding to indicated airspeed. In many descriptions this element is referred to as an aneroid or manometric capsule. Mechanical displacement inside the unit is converted into electrical signals for the connected equipment. Because of this, the condition of pressure lines is just as important as the electrical part of the unit. Leaks, blockage or moisture can distort the speed signal.

Operating modes of the KZSP unit

The KZSP is associated with several working modes used during operation and checks. In the matching or tracking mode, the unit follows the current airspeed and aligns the system with the existing value. In stabilization mode, it forms a mismatch signal when the actual airspeed differs from the set value. In control mode, the unit can be checked as part of maintenance or pre-flight system testing. The exact behavior depends on aircraft wiring and the installed autopilot / air data system version, so checks should follow the aircraft maintenance documentation.

Output signals from KZSP

The KZSP may provide several types of output signals. These include AC signals at 400 Hz with amplitude and phase changes related to the airspeed mismatch, DC signals for connection to autopilot channels, and potentiometric signals representing current speed. This mix of mechanical, pneumatic and electrical functions is typical for older aircraft control systems. When faults appear, they may look like unstable speed holding, wrong correction signal, no response in stabilization mode, disagreement with airspeed indication or failure of the connected readiness logic.

Supply and inspection of KZSP

When ordering the KZSP, it is useful to specify the helicopter type, system version and whether the unit is required for AP-34B, SVS-PN-15 or another related installation. The exact modification and connector arrangement should be checked against aircraft documentation. During inspection, maintenance personnel normally check the housing, connector, pressure fittings, tightness of pneumatic lines, power supply, output signal behavior and response in the required modes. For aviation supply, passport, label, storage condition, test status and remaining serviceability should be confirmed before installation.

Product Type: Aircraft airspeed corrector-setter
Designation: KZSP
Function: Setting, correction and generation of indicated airspeed mismatch signals
Application / Where Used: Helicopter flight-navigation equipment, air data systems and autopilot circuits
System / Installation Area: Mi-8 / Mi-171 flight and navigation equipment group; autopilot and airspeed control circuits
Compatible Aircraft / Equipment: Mi-8, Mi-8T, Mi-8MTV, Mi-171 and related helicopters depending on configuration
Associated Systems: AP-34B autopilot, SVS-PN-15 air data / navigation system and related equipment depending on installation
Associated Inputs: Static pressure and total / dynamic pressure from pitot-static system
Pressure Fittings: Static pressure fitting and total / dynamic pressure fitting
Sensitive Element: Built-in aneroid / manometric capsule responding to dynamic pressure
Main Operating Modes: Matching / tracking, stabilization and control
Speed Measurement / Working Range: Approximately 50 to 400 km/h depending on modification
Actuation / Response Error: Approximately ±2 to ±5 km/h depending on modification and test conditions
AC Power Supply: 36 V, 400 Hz
DC Power Supply: 27 V DC
Output Signal Types: AC mismatch signal, DC linear signal and potentiometric current-speed signal depending on system connection
AC Output Logic: Amplitude and phase change at 400 Hz proportional to deviation from selected speed
Housing: Sealed cylindrical aircraft instrument housing for panel or equipment-rack installation depending on version
Operating Temperature Range: −60 to +60 °C
Weight: Approximately 1.5 to 2.2 kg depending on production series
Technical Documentation: Product passport, aircraft maintenance documentation, AP-34B / SVS-PN documentation and test procedure as applicable

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