DA-30

Vertical-speed measurement through the static system

The variometer section is connected to the aircraft static-pressure line. Static pressure reaches both the sensitive manometric element and the instrument housing, but calibrated restrictions create a short delay in pressure equalisation. When the aircraft climbs or descends, the temporary pressure difference moves the vertical-speed pointer. During steady level flight, the pressure equalises and the pointer returns towards zero.

The displayed range is from −30 to +30 m/s. Reliable indication depends on the condition of the static line, the pressure fitting, the internal capillary passages and the mechanical linkage. A leak, blockage or contamination can cause delayed or incorrect readings. The instrument should therefore be checked together with the aircraft static system and not treated as an isolated electrical indicator.

Turn and slip functions of the DA-30

The turn section uses an electrically driven gyroscope. The instrument face provides reference marks associated with bank angles of 15°, 30° and 45° at a reference flight speed of 400 km/h. The corresponding reference angular turn rates are approximately 1.3°/s, 2.9°/s and 5°/s. These markings help the crew assess the direction and relative rate of a turn.

The curved-tube inclinometer below the pointers contains a freely moving ball. Under the combined effect of gravity and lateral acceleration, the ball shows whether the aircraft is slipping or skidding. A centred ball indicates a coordinated manoeuvre. During inspection, the ball must move freely, while the gyroscopic pointer should respond smoothly without excessive friction, sticking or irregular return to centre.

Electrical supply and cockpit installation

The variometer works pneumatically from static pressure, while the turn indicator requires electrical power. Yak-40 installation documentation describes a three-phase 36 V supply for the DA-30 turn section. Exact frequency, tolerances, circuit protection and connector pinout must be confirmed from the offered unit, its passport and the wiring diagram of the particular aircraft.

DA-30 is installed in the pilot instrument panel as part of the flight-instrument and air-data indication arrangement. Installation requires a secure mounting flange, a sealed static-pressure connection, the correct electrical connector and sufficient clearance behind the panel for the cylindrical housing and wiring. Scale lighting and any associated power converter must also be checked against the airframe configuration.

Documented applications and DA-30 identification

Technical and operating documentation records DA-30 installations on the Yak-40, Yak-52, An-28 and selected An-24 configurations. Applicability must still be checked by aircraft modification, equipment list and panel arrangement because different versions may use metric, imperial or modified instruments.

Before ordering, confirm the DA-30 marking, the m/s scale, connector, pressure fitting, mounting pattern and required documentation. Related executions include DA-30P and the imperial-scale DA-30 Feet / DA-30F. Similar external dimensions do not by themselves establish interchangeability. Exact mass, overall dimensions, operating temperature limits and connector pin count for this base execution require confirmation from its own passport.