DA-30 Feet

Imperial vertical-speed indication

The variometer section is connected to the aircraft static-pressure system. Static pressure reaches the sensitive element and the instrument case through passages with different response characteristics. During a climb or descent, the temporary pressure difference moves the vertical-speed pointer; after the pressure equalises in level flight, the pointer returns towards zero.

On DA-30 Feet the result is presented on an imperial scale in feet per minute. This makes the instrument suitable for a cockpit configuration based on international or imperial flight units. Reliable public documentation for the exact full-scale range and every graduation of this version was not found. Those values should therefore be confirmed from the offered instrument face, its passport or the applicable airframe documentation rather than copied from a metric DA-30.

Turn and slip information from the DA-30 family

The turn section uses a gyroscopic mechanism to show the direction and relative intensity of aircraft rotation about the vertical axis. It serves as a supporting reference during coordinated turns and can also help the crew recognise a disagreement with other flight instruments. Its operation requires the correct aircraft electrical supply.

A separate curved-tube inclinometer contains a freely moving ball. The ball responds to gravity and lateral acceleration, giving a direct indication of slip or skid. When the ball is centred, the turn is coordinated. These turn-and-slip functions are characteristic of the DA-30 family, but the condition of the gyroscope, bearings, damping, electrical circuit and inclinometer must be checked during inspection or bench testing.

Cockpit installation and system connections

The combined instrument is installed in the pilot instrument panel and requires both a sealed static-pressure connection and an electrical connection for the turn mechanism. DA-30 documentation describes a 36 V supply for the powered section. Exact phase, frequency, tolerance, connector pinout and circuit protection for the DA-30 Feet execution must be verified against the specific unit and aircraft wiring diagram.

The instrument is part of the flight-instrument and air-data indication arrangement rather than an independent navigation computer. A pressure leak can affect the vertical-speed indication, while loss of electrical power affects the gyroscopic turn section. The slip ball remains a mechanical reference. Installation should include checks of the pressure hose, electrical connector, mounting flange, panel clearance and scale visibility.

Yak-40 application and ordering identification

Yak-40 technical documentation lists the combined instrument as DA-30 with the DA-30F execution, confirming application of the feet-scaled version in selected Yak-40 cockpit configurations. This does not mean that every Yak-40 airframe uses the same scale or connector arrangement. Applicability must be checked by aircraft modification, equipment list and installation documentation.

Before ordering, confirm the markings DA-30 Feet, DA-30F or ДА-30Ф, the units printed on the vertical-speed scale, the electrical and pressure connections, the mounting pattern and the required documentation. For the separately documented metric execution, see the internal DA-30P product page. The two executions should not be treated as interchangeable solely because their housings appear similar.