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Helicopter upgrade

Helicopters of Mi-8/17 family are equipped as standard with bracket of the rear main gear box compartment (MGBC) No. 8AT-5104-305.

This bracket is designed to mount combination control hydraulic actuators КАУ-30Б and РА-60Б or КАУ-115АМ to the rear wall of the main gearbox and is made of magnesium alloy. Modern helicopters are equipped with aluminum alloy bracket No. 8AT-5104-405. Compared with a magnesium bracket No. 8AT-5104-305, aluminum bracket No. 8AT-5104-405 has increased service life limit and life time, as well as increased resources of the boosted control part (BCP).

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There are several versions of the bracket No.8AT-5104-305:

  • 8АТ-5104-305-1 – Bracket with two sensors МУ-615А (angular displacement sensors) in the points of the bracket attaching to the rear wall of the main gearbox. Sensors МУ-615А are designed to convert angular displacements of the helicopter controls to electrical values (voltage) and to transfer parametric data to the flight recorder. All helicopters made by Ulan-Ude Aviation Plant, JSC are equiped with the bracket, except for Mi-171A and the Mi-171A1
  • 8АТ-5104-305-3 – Bracket with two sensors МУ-615А installed directly in the “body” of the bracket with four studs. This technique has been mastered at Ulan-Ude Aviation Plant, JSC and significantly different from the installation technique of angular sensors on brackets of helicopters made by Kazan Helicopter Plant, PJSC. Later, the developer (Mil Moscow Helicopter Plant, JSC) has decided to install the МУ-615А sensors on helicopters made by Ulan-Ude Aviation Plant, JSC in places of mounting of the bracket on the rear wall of the main gearbox. In this connection, the bracket No. 8AT-5104-305-3 was restricted in production, and bracket with the drawing number 8AT-5104-305-1 was used instead
  • 8АТ-5104-305-5 –Bracket with two sensors МУ-615А installed in the points of the bracket attaching to the rear wall of the main gearbox on the Mi-171A and Mi-171A1 helicopters. Due to the КАУ-30Б combination control hydraulic actuator is installed in this bracket, the bracket No.8AT-5104-305-5 has another structure different from the design of brackets No.8AT-5104-305-3 and No.8AT-5104-305-1

Bracket No.8AT-5104-405 is interchangeable with serial brackets Nos.8AT-5104-305, 8AT-5104-305-1, 8AT-5104-305-3, 8AT-5104-305-5.

Brackets Resources:

Characteristics 8АТ-5104-305 (magnesium bracket) 8АТ-5104-405 (aluminium bracket)
Assigned service life 5500 hours

on project

*8000 hours for Mi-171, Mi-171A, Mi-171A1

Service life limit 25 years
(30 years – for RF civil aviation)
35 years

 

Part resources:

8АТ-5104-305
(magnesium bracket)
8АТ-5104-405
(aluminium bracket)
8АМТ-5104-200 8АМТ-5104-200-3
Assigned service life Service life limit Assigned service life Service life limit
5500 hours 25 years
(30 years – for RF civil aviation)
8000 hours 25 years
(30 years – for RF civil aviation)
171А-5104-200 171А-5104-200-3
Assigned service life Service life limit Assigned service life Service life limit
5500 hours 25 years 8000 hours 25 years

The following service bulletins have been issued for the possibility of replacement of magnesium bracket 8AT-5104-305 with the aluminium bracket 8AT-5104-405 on helicopters Mi-8AMT, Mi-171, Mi-171E, Mi-171A1

  • № АМТ3582-БУ-БЭ-Г «Helicopter Control – Replacement of Bracket 8AT-5104-305 with Bracket 8AT-5104-405 in the Structure of Post-booster Guidance Subsystem»;
  • № АМТ3582-БУ-БЭ-АБ «Helicopter Control – Replacement of Bracket 8AT-5104-305 with Bracket 8AT-5104-405 in the Structure of Post-booster Guidance Subsystem»;
  • № 171-3582-БУ «Helicopter Control – Replacement of Bracket 8AT-5104-305 with Bracket 8AT-5104-405 in the Structure of Post-booster Guidance Subsystem»;
  • № 171А1-3597—БУ «Helicopter Control – Replacement of Bracket 8AT-5104-305 with Bracket 8AT-5104-405 in the Structure of Post-booster Guidance Subsystem».