DPS

How the DPS detects fire conditions

The DPS detector is based on a thermoelectric principle. Inside the unit there is a battery of thermocouples connected in series. Part of the thermocouple junctions is exposed to the surrounding hot airflow or flame, while the other part is shielded inside the body and reacts more slowly. When a fire starts, the exposed junctions heat up much faster than the protected junctions. This temperature difference creates thermoelectric voltage, which is sent to the SSP-FK-BI executive block for further processing.

DPS signal to the SSP-FK-BI Series 2 block

The DPS itself does not switch cockpit lamps or release fire extinguishers. It generates a small electrical signal that is interpreted by the SSP-FK-BI Series 2 executive block. When the summed signal from the connected detector group exceeds the system threshold, the executive block issues the fire warning command and, depending on aircraft configuration, may also take part in the fire-extinguishing control chain. This separation is important during maintenance: the detector, wiring, socket, executive block and cockpit indication must all be checked as one system.

Grouping of DPS detectors on aircraft

On aircraft such as Mi-8 family helicopters, DPS detectors are normally connected in groups rather than as isolated single sensors. A typical arrangement is series connection of several detectors in one channel, so that the executive block receives a combined signal from the protected zone. This helps reduce false triggering from a small local temperature disturbance and makes the system react to a more convincing fire condition. The exact grouping, number of detectors and protected zones are defined by the aircraft wiring diagram and fire-protection documentation.

Mechanical design of the DPS detector

The DPS detector is a very light aircraft unit, but its installation is critical. The sensing area is protected by a metal mesh or guard that allows hot air and flame to reach the exposed junctions while protecting the sensor from mechanical damage and debris. The detector is installed into a special socket, such as SSP-2I-RM type socket depending on the aircraft system. Poor contact, contamination, damaged mesh, incorrect positioning or loose installation can affect the signal and reduce the reliability of the fire warning system.

Aircraft use and protected area of DPS

One DPS detector can protect a limited area of a compartment, but real aircraft installations normally use several detectors distributed around the protected zone. This is especially important in engine and gearbox compartments, where airflow direction, hot surfaces and possible fire sources are not uniform. The detector must be placed where it can react quickly to fire conditions, not merely where installation is convenient. For this reason, replacement and relocation must follow the aircraft maintenance manual, not only general detector specifications.

Supply and identification of DPS detectors

When ordering DPS detectors, the exact designation and system compatibility should be confirmed. It is important to specify whether the detector is required for the SSP-FK system, SSP-FK Series 2 installation, or another aircraft fire warning system. Completeness may include only the detector or may require sockets, connectors, mounting parts and documentation. Before installation, technicians normally check the passport, external condition, contact area, mesh protection, storage condition, compatibility with SSP-FK-BI, and compliance with the aircraft fire warning system layout.

Related system equipment: SSP-2I-RM, SSP-FK Series 2, SSP-FK-BI Series 2. These positions are grouped by system function and installation context, not as interchangeable replacements.