2416-17.5

KO-50 heater protection with 2416-17.5

In the KO-50 heating and ventilation installation, the 2416-17.5 is used as part of the automatic protection and fuel shut-off logic. The unit is connected to the electrical circuit that controls fuel supply to the heater. If the air temperature at the outlet of the heater rises above the permitted value, the thermal switch opens the circuit and supports emergency interruption of fuel delivery. This prevents further heating and helps keep the heater, air ducts, wiring, and downstream equipment within the required operating conditions.

2416-17.5 fuel shut-off control function

The 2416-17.5 may operate in the control circuit of an electromagnetic fuel valve used with the KO-50 heater. In this role, it interrupts the power supply circuit of the valve when the temperature limit is exceeded. Depending on the aircraft configuration, the thermal switch may be associated with valves such as 772D or 610200A, as well as relay and contactor circuits used in the heater control system. The exact connection must always be checked against the wiring diagram and technical documentation of the specific helicopter modification.

Contact operation of the 2416-17.5 switch

The 2416-17.5 is normally closed during standard heater operation and opens its contacts when the sensitive element reaches the actuation temperature. This makes the unit suitable for protection circuits where loss of continuity must result in fuel shut-off or heater shutdown logic. The device does not provide a proportional temperature reading. It works as a discrete safety and control element, giving the system a clear electrical signal when the air temperature has reached the specified limit. This simple switching principle is well suited to aircraft systems where reliability and predictable response are required.

2416-17.5 sensing element and construction

The thermal action of the 2416-17.5 is based on expansion of internal elements made from heat-resistant materials. The design uses a temperature-sensitive assembly that reacts to heating in the airflow and mechanically acts on the contact group. The body and sensing components are intended for installation in a hot-air environment at the outlet of the KO-50 heater. The switch must withstand vibration, local heating, and the mechanical loads typical of helicopter operation. During inspection, attention is normally paid to the housing, mounting condition, wiring approach, and condition of the lead termination.

System compatibility of 2416-17.5 with related switches

In KO-50 heater systems, the 2416-17.5 may work together with other temperature-control devices, including the 2416-4 thermal switch and the 1374A-5 thermal switch. Each of these units has its own operating point and function within the heater control logic. The 2416-17.5 is associated with overtemperature protection, while lower-temperature switches may be used for fan control, heater readiness, or other automatic functions. For correct replacement, the designation must be checked carefully, because similar-looking thermal switches can have different actuation temperatures and different roles in the circuit.

Identification, supply, and maintenance of 2416-17.5

The 2416-17.5 belongs to aircraft technical equipment and is supplied with passport, label, or quality documentation depending on condition and source. It may be available as new production or as a first-category storage item, subject to documentation and acceptance status. Before installation, the part should be matched with the aircraft parts catalog, KO-50 heater documentation, and maintenance procedures for the relevant helicopter version. During scheduled maintenance, the unit is inspected for secure installation, visible damage, cracks, wiring condition, and correct routing of the connected harnesses.

Related system equipment: 2416-4, 1374A-5, KO-50, 610200A. These positions are grouped by system function and installation context, not as interchangeable replacements.

Confirmed installation context includes Mi-8 / Mi-17 family helicopters. The exact execution and installation position must be checked against the illustrated parts catalogue and documentation for the specific aircraft.