SSP-FK BIS

Operation with DTBG detector circuits

The standard SSP-FK configuration has six detector channels. Each channel works with three DTBG thermoelectric fire detectors, allowing the system to monitor several protected zones independently. When a detector group produces the required signal, the executive unit changes the state of the related warning or control circuit. The cockpit indication and the subsequent operation of the fire-protection equipment depend on the aircraft wiring connected to that channel.

A complete SSP-FK system set can include one SSP-FK BIS unit, four mating electrical connectors, eighteen SSP-2I-RM detector sockets and eighteen DTBG detectors, with two spare DTBG detectors. This composition explains how the block interacts with the other parts of the system. The normal supply item is the executive unit itself; mating connectors, detectors, sockets and other components are included only when they are expressly listed in the quotation.

Electrical and functional parameters

The SSP-FK system operates from the aircraft 27 V DC supply with a tolerance of ±2.7 V. For the configuration with DTBG detectors, the detector-chain operating signal is 14–30 mV and the nominal response delay is 1 second. The DTBG detector response temperature is not lower than 180 °C. These values describe the operation of the complete detector and executive-unit circuit and should be considered together with the limits stated for the installed aircraft configuration.

During troubleshooting, the unit is checked together with the detector loops, SSP-2I-RM sockets, mating connectors and aircraft harness. A missing warning may be caused by a detector, a poor contact, damaged wiring, an incorrect channel connection or the executive unit. Connector pin assignments, insulation checks, bench testing and adjustments must follow the maintenance data for the aircraft and the installed SSP-FK configuration.

Aircraft application, construction and connection

SSP-FK BIS is used in fire-warning installations associated with the Yak-40, Mi-8 and Mi-24. The Yak-40 installation uses two executive units, and the listed mass of one unit is 2.65 kg. Aircraft type alone is not enough for selection because wiring, connector arrangement and system generation may differ between modifications.

The unit is housed in a rectangular metal enclosure with a textured grey finish and a mounting base. Four circular connectors marked Ш1, Ш2, Ш3 and Ш4 connect the detector channels, power supply and output circuits according to the aircraft wiring diagram. The metal enclosure protects the internal relay and signal-processing components and provides rigid attachment at the installed location.

Selection and ordering

When replacing the unit, compare the complete SSP-FK BIS designation, the four-connector layout, connector keying, detector type and channel wiring with the installed equipment. SSP-FK Series 2 uses another executive-unit designation, SSP-FK-BI Series 2, together with DPS detectors. A similar housing or family name does not establish interchangeability between these versions.

For a quotation, specify the aircraft type and modification, the installed fire-warning system, the required quantity and the requested document set. Also state whether mating connectors, detector sockets or DTBG detectors are required with the unit. Aviamisto can supply the SSP-FK BIS block subject to confirmation of condition, configuration and accompanying documents. Related aircraft control equipment is available in Electronic Control Units.