246-1517-000

Tail gearbox 246-1517-000 in the anti-torque system

246-1517-000 is a helicopter tail gearbox used in the tail rotor drive system of Mi-family helicopters. The unit transfers torque from the tail transmission line to the tail rotor and supports operation of the anti-torque system. It is installed at the end of the tail drive path, where rotational power arriving through the shaft line must be redirected to the tail rotor assembly. In flight, the gearbox works continuously with the tail rotor and is directly connected with directional control of the helicopter.

Torque transmission through the 246-1517-000 gearbox

The 246-1517-000 gearbox transmits torque, changes the direction of power flow and provides the required speed relationship for tail rotor operation. Power reaches the unit from the main transmission through the intermediate gearbox and tail shaft system. Inside the tail gearbox, the bevel gear arrangement redirects rotation to the tail rotor output. This allows the tail rotor to produce anti-torque thrust and provide yaw control. Since the unit operates under continuous mechanical load, the condition of gears, bearings, lubrication passages and sealing elements is important for stable transmission performance.

246-1517-000 on Mi-family helicopter applications

The 246-1517-000 tail gearbox is used on Mi-family helicopters equipped with compatible tail rotor drive systems. Typical applicability includes Mi-8, Mi-17, Mi-171, Mi-8AMT, Mi-8MTV, Mi-172, Mi-14 and Mi-24 / Mi-25 / Mi-35 configurations, depending on aircraft documentation and installed transmission equipment. Because these helicopters may differ by modification, repair history and service bulletin status, applicability should be confirmed through the aircraft parts catalog and maintenance documentation. A visually similar tail gearbox should not be treated as interchangeable without checking the exact designation and approved configuration.

Lubrication and thermal operation of 246-1517-000

The 246-1517-000 gearbox has an internal lubrication system intended to support gear and bearing operation during continuous flight cycles. The oil works under mechanical load, temperature variation and vibration typical for helicopter tail transmission units. Correct oil type, fill quantity and temperature control are important because inadequate lubrication can increase wear, heating and risk of damage to gear teeth or bearing surfaces. Winter operation may require the specified oil mixture according to the applicable documentation. During maintenance, oil condition, leakage, contamination and metal particles should be checked together with gearbox service records.

System integration of the 246-1517-000 tail gearbox

The 246-1517-000 is installed as part of the full tail rotor drive and control system. It interfaces with the tail transmission shaft line, tail boom mounting structure, tail rotor hub area and control-related assemblies. The housing is designed for installation at the tail end of the helicopter and supports the internal bevel gear arrangement under vibration and changing flight loads. Since the gearbox is part of a rotating transmission system, correct mounting, alignment, oil filling, sealing and documentation compliance are all important during overhaul or replacement.

Identification and interchangeability of 246-1517-000

The gearbox may be referenced under several designations, including 246-1517-000, 2461517-000, 246-1517-00 and 2461517000. It may also be interchangeable with 8AT-1730-000 after modification according to bulletin M-466DM. This interchangeability should not be assumed by part number alone. The modification status, helicopter type, installed shaft system, documentation and service bulletin compliance must be verified before installation. For correct ordering, it is useful to specify the aircraft type, required condition, passport availability, overhaul status and whether service or storage documentation is included.

Product Type: Tail gearbox
Designation: 246-1517-000
Alternative Designations: 2461517-000, 246-1517-00, 2461517000
Function: Transmission of torque to the tail / anti-torque rotor
Application / Where Used: Mi-family helicopter tail rotor drive systems
System / Installation Area: Tail rotor drive and transmission system
Compatible Aircraft / Equipment: Mi-8, Mi-17, Mi-171, Mi-8AMT / Mi-8MTV / Mi-172, Mi-14, Mi-24 / Mi-25 / Mi-35 helicopters
Transmission Function: Torque transmission, rotational speed reduction and angular redirection of power flow
Gear Arrangement: Bevel gear arrangement with angular power transmission
Gear Ratio: 0.4318
Oil Type, Standard: TS-GIP per OST 3801260-82
Oil Type, Winter: Mixture of 1/3 AMG-10 + 2/3 TS-GIP
Fill Oil Capacity: 1.6 kg
Continuous Oil Temperature Limit: +110 °C
Short-Term Oil Temperature Limit: +115 °C
Mass, Passport: 58.7 +0.5 / −0.8 kg
Measured Mass, Factory Record: 58.2 kg
Interchangeability: With 8AT-1730-000 after modification per bulletin M-466DM
Precious Metals: None
Material Composition: Aluminum approx. 1.0 kg; magnesium approx. 17.4 kg
Condition: As applicable
Documentation: Factory passport, service documentation, overhaul documentation, aircraft parts catalog

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