Oh, My goodness…

(Cross posted from AirPogue)

…Showing some thigh! Well, not really, but it is a little more exposure than the engine usually gets.

We have regular inspections on our helicopters, many of which are based on flight hours. They range from the 40 hour and 120 hour inspections which get progressively more thorough to the phase maintenance where major disassembly, inspection and repairs take place. This engine was pulled as part of a phase inspection. During the borescope inspection of the compressor some damaged blades were found so the case was split so the blades could be repaired. You can see a very clear picture of the first five stages of compression in our engine – a sixth stage is just out of sight on the left. The inlet side of the engine is to the right, with the accessory module on top of it. Think of all the stuff on your car engine – starter, alternator, oil pump, fuel pump, etc., all that stuff is driven off this module. On the left side of the picture is the hot section of the engine. Those holes around the outside of the casing are where the fuel injectors go. When the engine is running a ring of fire that doesn’t touch any of the case or combustion liner (it’s way too hot) provides all the energy to power the helicopter, in this case about 1500 horsepower. Not attached at the moment, although you can see it on the bench near the wall to the left is the power turbine section. All the hot air from the hot section spins a couple of turbines that turn the shaft sticking up in the air which is attached to the main transmission in the helicopter. Interestingly enough, 80% of the air that goes through the engine provides cooling, only 20% is used for combustion. That’s a lot of energy in a small place.


Filed under Aeronautical Engineering

4 responses to “Oh, My goodness…

  1. Bill Brandt

    I remember seeing a turbine from the OH-58 (Jet Ranger) and was surprised at how small it actually was. Of course that is a much smaller – in size and capability – as (presumed?) a Blackhawk.

    And compared to the moving parts of, say, a P&W R4360 or RR Merlin V12, a turbine is a modfel of simplicity, isn’t it?

    Metallurgy is the difference.

    I remember reading the engine that powered the Me262, I guess the world’s first operational jet fighter, the TBO on the Junkers-Jumo engines was 8 hours. Part of that was because of the material shortage of the Germans requiring them to use steel, but still…8 hours.

    At what hours did htis engine get pulled?

    Thanks for the picture Pogue

  2. The R-3350 Turbo compound-no wonder jets replaced them
    Took me two fire seasons to fully master that beast.

    • Bill Brandt

      I used to be docent at an aerospace museum and they had a P & W R4360 on display – complete with cutaway.

      What a monster.

      I asked one of the visitors what it would be like to have to overhaul one of those – and he said that he did. You had to carefully categorize and group each cylinder’s parts separately – all 28 cylinders.

      He said that once a mechanic played a joke and hid one of the parts – or put an extra in I think – driving the assembler nuts until let in on the “joke”.

  3. Same engine is fitted on Saab 340 !

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s