Main external fuel tanks are vessels intended to place the requisite amount of fuel on board the helicopter. These tanks (2 units) are installed externally on the right and left sides of the fuselage. Each tank is fastened to the fuselage with steel bands, which in turn are fixed to special stamped brackets.
In case of emergency landing of the helicopter, a fire often breaks out onboard due to deformation of the fuel tanks, short-circuiting or contact of spilled fuel with a source of fire or high temperature. In this case, the probability of injury and death of the crew and passengers increases significantly.
Consequently, in order to increase the survivability of Mi-8AMT and Mi-171E helicopters during operation (emergency landings, mechanical damage of tanks), the main external fuel tanks are being replaced with self-sealing main external fuel tanks.
The self-sealing fuel tank is a tank with a multi-layer coating (protector) applied on its outside to reinforce the tank walls and prevent fuel leakage during mechanical damage.
The protective cover contains organic elastic material, which swelling upon contact with aviation fuel and seals the holes formed during mechanical damage to the tank.
The primary work to be done when replacing the main external fuel tanks with self-sealing fuel tanks on Mi-8AMT and Mi-171E helicopters includes:
- Dismantling of external fuel tanks (dismantling of SKES-2027B, SKES-2027I, SKES-2027B, ETsN-91S/ETsN-91B, alarm sensor DSMK10-10, fairings, etc.);
- Installation of external self-sealing fuel tanks (left and right side):
- Replacement of gaskets on band attachment brackets;
- Installation of electric centrifugal pump ETsN-91S on self-sealing fuel tanks;
- Installation of fuel gage SKES-2027B on self-sealing fuel tanks;
- Installation of fuel hoses;
- Installation of fairings (during installation of fairings and edge strips, their additional adaptation on site may be required);
- Restoring the paint coat to the original helicopter color.
To replace the main external fuel tanks with self-sealing main external fuel tanks on Mi-8AMT and Mi-171E helicopters, the following service bulletins are issued:
- АМТ5041БУ-Г - Replacement of External Fuel Tanks with Self-sealing External Fuel Tanks.
- 171Е-5041-БУ - Replacement of External Fuel Tanks with Self-sealing External Fuel Tanks.
- АМТ5041БЭ-Г - Helicopter equipment with Self-sealing External Fuel Tanks- Release of the Supplement to the manual for technical operation of the Mi-8AMT helicopter 8AMT.0000.000RE.Д-5111.
- 171Е5041БЭ - Helicopter equipment with Self-sealing External Fuel Tanks- Release of the Supplement to the manual for technical operation of the Mi-171Е helicopter 8AMT.0000.000RE.Д-5112.