Monday, January 5, 2009

MiG-23 Lubrication

From our friends in Poland... details of the MiG-23 lubrication items.

Engine Oil:
Turbonycoil 210A
or Mobil Turbo 319A-2
or Exxon Turbo Oil 2389

Hydraulic Oil:
Aeroshell Oil 390
or Aeroshell ASF-41A

Wing Pin Grease:
or Aeroshell Grease 17

Wheel Bearing Grease:
or Aeroshell 15A
or Aeroshell Grease 22

15 SCS 45 - 2 batteries - 24 volts

Unclear at this point what the difference between the above hydraulic fluids and 5606 (Aeroshell Fluid 4) or AMG-10 is. Our current understanding is that 5606 is explosive in a mist form and at very high working pressures (which occur in the MiG-23 more so than they do in some of the slower aircraft) a pin-hole leak makes a very good mist cloud.

Bud's assessment of the battery situation:

Battery - Original equipment is a Silver-zinc oxide, expensive and high maintenance.
Battery alternate (1) - Ni-cad alternate for Migs is available, heavier, less capacity, still high maintenance and short life.
Battery alternate (2) - Odyssey (2x925MJ) same weight as ni-cad, better characteristics than ni-cad, need to check altitude spec.

The original equipment battery appears to be a 45ah silver-zinc battery (ag-zn-02, pdf attached). The factory, Krusik in Yugoslavia was heavily damaged during the "NATO aggression" in 1999. SBS in Wisconson carries both a silver zinc and ni-cad battery for the Mig23 (sbs aviation pdf attached).A number of countries (especially India) seem to manufacture or use alternate batteries in the 25ah capacity range.

Silver zinc is a very (very) high energy to weight ratio battery. It is typically used where space/weight is a premium and cost is not an issue. The Krusik specification would imply that the battery could provide (3) 700 amp start attempts and run 20a of on-board avionics for 2 hr. Design life is 120 (engine start) cycles. Based on the battery spec, each start attempt would be an equivalent of 24 sec at the 700 amp draw)

This silver-zinc battery is a wet battery and it is vented. Individual cells can be replaced as they fail. "Forming" a new battery or new cell is a critical process in order to obtain full rating. Typical comments of a life of 25 to 30 cycles are found in other general references to silver zinc batteries. Because of the different chemistry, full battery voltage is only 22.5 vdc.The battery is very light (17.5 kg) and powerful when operating at rated capacity.

There are several start-up companies re-inventing the silver zinc process for laptop and cell phone use. Their projection is that 2009 will be "the year of the silver-zinc battery". Nothing is readily available from them to be repackaged yet. Silver zinc is "greener" than Lithium Ion.

Ni-cad alternates are heavier (23.5 kg) and less powerful (25-27 ah). The ni-cad battery does not appear to provide as much starting current (300 amps+ for 30sec), If there are two batteries in the A/C that would about get you to a 700 amp start. (we need aircraft/engine manual to know start draw). Ni-cad has its own pecularities for charging and obtaining maximum life and performance.

Two Odessy 925MJs will fit in the required replacement profile. These are the batteries we are using in the Mi-2s and the Mi-24 (as well as L29 and L39). The 925 is a 28ah battery capable of one start cycle of 700 amps for 30 seconds. The battery fits the temperature range profile but I have not found an altitude spec (we will be going higher and it is a non-vented battery). I can probably get that from the factory.

Note that we probably want to standardize in the future on the 925MJ's instead of the 925MJT's because of the slightly smaller profile (The T has an automotive terminal, the non-T has a screw mount).


  1. Aeroshell 17 is now Aeroshell 33MS.

    AeroShell Grease 33MS is an extreme pressure (EP) grease based on the proven lithium complex technology of AeroShell Grease 33, and is fortified with 5% Molybdenum Disulphide.

    The benefits of Grease 33MS include:
    # Improved anti-wear and corrosion resistance over AeroShell Grease 17
    # It is fully compatible with AeroShell Grease 33, so reduces the risks and problems associated with misapplication
    # Load carrying and EP properties equal to that of the well established AeroShell Grease 17
    # Fully approved to MIL-G-21164D It possesses enhanced anti-wear and anti-corrosion properties and is particularly suitable for lubricating heavily loaded sliding steel surfaces, such as, for example, bogie pivot pins on aircraft landing gear-assemblies.

    AeroShell Grease 33MS is a direct alternative to AeroShell Grease 17, but when changing from (clay-based) ASG 17 to (Li-complex based) ASG 33MS, the normal rules on grease changing should be applied.