MSL-3-2s

MSL-3-2S rotating signal beacon for aircraft visibility

The MSL-3-2S is a rotating lamp-type aircraft signal beacon used for external visual marking of helicopters during night operation and in reduced visibility. The unit produces a red flashing warning signal that helps make the aircraft more visible to other crews, ground personnel and nearby equipment operators. It is installed on external aircraft surfaces and works as part of the aircraft lighting and anti-collision warning system. In some documentation, the same unit may also be referenced as MSL-3F-2S.

Red flashing warning function of the MSL-3-2S

The main function of the MSL-3-2S is to create a clearly visible red flashing signal. This signal is used to improve aircraft recognition in darkness, fog, rain and other difficult operating conditions. Unlike a steady navigation light, the MSL-3-2S produces a rotating flash pattern, making the aircraft easier to notice from different directions. On helicopters, this is especially useful during ground operation, start-up, taxiing, landing-area work and low-visibility flight conditions.

MSL-3-2S lamp and optical arrangement

The MSL-3-2S uses two SM3 28-60 incandescent lamps installed on a rotating optical platform. Light from the lamps passes through a red glass filter, forming the required warning color. The rotating platform and optical layout provide all-round visual coverage. Since the beacon relies on both lamps and a mechanical rotating system, maintenance should cover not only lamp replacement, but also the condition of the drive, filter, contacts, bearings, connector and mounting base.

Electromechanical drive of the MSL-3-2S beacon

The beacon includes an internal electromechanical drive that rotates the lamp platform and creates the flashing effect. Stable rotation is important because irregular speed can change the flash pattern and reduce the visual effectiveness of the beacon. The unit operates from the standard 27 V DC aircraft electrical system. During inspection, technicians should check power supply, connector condition, rotation, lamp operation, filter condition and signs of vibration-related wear.

MSL-3-2S on Mi-8, Mi-17 and Mi-171 helicopters

The MSL-3-2S is widely used on Mi-8, Mi-17 and Mi-171 helicopters as an external warning and anti-collision beacon. It is suitable for installation on fuselage or structural mounting points specified by the aircraft documentation. Because helicopter external lighting is exposed to vibration, weather and temperature changes, the beacon must be securely mounted and mechanically sound. Exact installation position, wiring and mounting details should be checked by helicopter modification and maintenance documentation.

Ground and obstruction lighting use of MSL-3-2S

Besides helicopter applications, the MSL-3-2S may be used for ground safety and obstruction marking. It can be installed on masts, towers, airport infrastructure and industrial facilities located near flight zones, where a red flashing signal is required for visibility. In these applications, the unit works as an external warning light for ground-based objects. Power supply, mounting method and environmental protection should be checked according to the installation site and local operating requirements.

Construction and installation of the MSL-3-2S

The MSL-3-2S has a compact, vibration-resistant construction suitable for external aircraft installation. The assembly includes a base, rotating platform with lamps, red glass filter, electromechanical drive and plug-type connector. Mounting is normally performed through the base, typically using a three-screw arrangement. Before installation, the housing, glass filter, lamp holders, connector, mounting holes and rotating mechanism should be inspected. Damage to the filter or poor rotation can reduce the beacon’s effectiveness.

Supply and documentation for MSL-3-2S

For procurement, the beacon should be specified by the full designation MSL-3-2S, with MSL-3F-2S noted only as an alternative reference where applicable. The unit may be supplied new, overhauled or serviceable depending on availability. For aircraft use, test report, certificate of conformity or release documentation may be required by the customer or operator. Before shipment, the beacon should be checked for lamp operation, rotation, electrical consumption, connector condition, filter integrity and external condition.

Product Type: Rotating aircraft signal beacon
Designation: MSL-3-2S
Alternative Reference: MSL-3F-2S in some documentation
Category: External aircraft lighting / signal beacon
Function: Red flashing visual warning and aircraft visibility marking
Application / Where Used: Helicopter external lighting systems and ground obstruction lighting
Compatible Aircraft / Equipment: Mi-8, Mi-17, Mi-171 helicopters; masts, towers, airport and industrial structures depending on configuration
Light Color: Red, flashing
Light Source: 2 × SM3 28-60 incandescent lamps
Supply Voltage: 27 V DC
Flash Rate: Approx. 50–108 flashes per minute
Construction: Base, rotating lamp platform, red glass filter, electromechanical drive and plug-type connector
Mounting: External mounting via base, typically three-screw mounting
Operating Conditions: Outdoor use, night operation and low-visibility conditions
Shock / Vibration Resistance: Designed for helicopter external installation
Operating Temperature Range: −60 to +60 °C
Dimensions: Approx. 152 × 120 × 102 mm
Weight: Not more than 1.0 kg
Condition: New / overhauled / serviceable depending on availability
Documentation: Test report, Form 1 or Certificate of Conformity on request
Warranty: 6 months standard; extended warranty available by agreement
Packaging: Individual export packing
Logistics: Worldwide shipping, export documentation, packing and inspection available

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Returns & Changes (Restocking Fee)
For selected items, a RESTOCKING FEE of 10% may apply in case of return, order cancellation, or changes to the order specifications. This condition applies only to certain products and is confirmed at the order approval stage.

Warranty
All products are covered by a standard 6-month warranty.
Extended warranty is available upon request and is agreed individually; it may affect the final product price.