SM 28-10

SM 28-10 in aircraft lighting and signalling systems

The SM 28-10 is used inside aircraft and helicopter lighting equipment where a compact 10 W lamp is required. It may be installed in cabin lights, cockpit fixtures, passenger compartment lights, illuminated panels, instrument backlighting and signal indicators. Since many Soviet, Russian and Ukrainian aircraft systems use a nominal 27–28 V onboard network, the lamp is suitable for a wide range of aviation applications, provided that the base type and lamp power match the installed unit.

Electrical characteristics of the SM 28-10 lamp

The lamp has a nominal voltage of 28 V and a nominal power of 10 W. Its typical luminous flux is listed as 80 lm, while some modifications or references may show up to 60 lm depending on version and production data. The average operating life is not less than 100 hours. The SM 28-10 can be used in DC circuits and in AC circuits where the equipment documentation allows it. Some references mention operation with 50 Hz AC.

SM 28-10 and old designation SM-15

The SM 28-10 may be referenced under the older designation SM-15. This is important when working with older aircraft documentation, warehouse labels, repair records or equipment manuals. When replacing a lamp marked SM-15, the voltage, power, bulb size, base type and equipment requirements should still be checked. A matching old designation alone is not enough if the lamp holder or electrical version differs.

Base types and modifications of SM 28-10

The SM 28-10 is produced with two main bayonet base versions. The B15s/18 version has a single-contact bayonet base, while the B15d/18 version has a two-contact bayonet base. These versions are not interchangeable unless the lamp holder is designed for the same contact arrangement. Before ordering or replacing the lamp, the old lamp should be checked: one contact on the base end means B15s, while two contacts means B15d.

Bulb size and physical design of SM 28-10

The SM 28-10 is a compact lamp with a bulb diameter up to 20 mm and overall length up to 37 mm. Its weight is not more than 8 g. The small size allows it to be installed inside compact aircraft indicators, panels and interior lighting fixtures. The lamp uses a clear glass bulb and provides direct light output, while the final color and distribution depend on the lens, diffuser, filter or housing where it is installed.

Non-aviation applications of SM 28-10

Besides aviation, the SM 28-10 is used in equipment with compatible 28 V lighting circuits. It may be found in trolleybuses, trams, railway vehicles, medical equipment, laboratory devices, military equipment, special vehicles, control panels and automation boards. For aviation supply, however, the aircraft lamp marking, correct base type and applicable quality documents should be confirmed before shipment.

Supply and replacement checks for SM 28-10

For procurement, the lamp should be specified as SM 28-10 / SM 28-10, with SM-15 noted as the older designation if relevant. The required base type must be confirmed: B15s/18 or B15d/18. Before installation, the lamp should be checked visually, the filament should be tested for continuity, and the base contacts should be inspected. In aircraft use, replacement should follow the equipment documentation, not only the general lamp rating.