Allison 250 Test Cell

[alan]

Hello Everyone!

For my senior project at college*, two classmates and I are completing the setup of the Allison 250 test cell. This test cell incorporates a dynamometer and a data acquisition unit that feeds information to a computer in the control room where the info. is displayed on a computer monitor.


The main goal is to setup the test stand so swapping the two Allison engines we have will be fast and easy.


This is my first time working with this engine and a dyno so it will be a great learning experience!

[Johansson]

Hi Alan,

Really cool project! For my last year project at school I modeled a telescopic shelf for a computer keyboard, it turned out so heavy it would have tipped the table over. I am NOT jealous of you in other words...

Cheers!
/Anders

[Richard OConnell]

Wow, beautiful engine Alan!! You're a lucky man to get to work with such a nice piece of hardware

[alan]

First on the list of things to do is make the test stand safe for students and to protect if from students.

The power receptical use to be mounted in the open under where the oil hoses disconnect. the junction box will now enclose the power receptical and I will also mount away from the oil lines.

The oil pump for the dyno use to be mounted to the wall of the test cell, so we re-mounted it to the dyno's test stand.

The fuel boost pump was also mounted in an inconvienant location and if you look at the wire coming of it, it has a cheap automotive butt spice. There are a lot of little discrepancies like this that we have fix.

[racket]

Hi Alan

LOL........there always seems to something to fix on a test stand ............those hurriedly mounted bits and pieces we add on the spur of the moment thinking we'll do a permanent job of it latter , a "latter" that never comes :-)

That'll be a nice piece of kit to play with once things are "cleaned up "

Just love the 250 engines air diffusers at the end of those 2 skinny delivery tubes, that combustor outer can is a work of art.

Cheers
John

[alan]

Well progress is coming along slowly but surly.



The main control box is turning out okay after we drilled the holes switches and LEDs upsidown . to fix it we just cut the whole section out and make a new front panel that we will rivet on later.


Also, if anyone has access to a manual for this Allison (t63) 250, I would like to know the right type of oil we need to use. If someone could get this information to me or even better, show me where I can access a manual it would be much appreciated

[alan]

Now there are two main issues that need addressed before we can even think about running the engine.

One issue is that we have to vent all the exhaust outside of the test cell. One day I came in to do some more work and found stove pipe bent around the exhaust oultets.

I need replace this cheap exhaust ducting with something else, but im not sure what. My request to purchase unairworthy exhaust stacks got denied. So I am open to any suggestions.

[racket]

Hi Alan

That exhaust is a bit rough :-(

You're right to question its effectiveness , the length and bends will probably put more backpressure on the engine than is normal .

Not nice to see a beautiful engine treated like that .

Cheers
John

[gidge348]

Agree, that exhaust looks a bit ......"Agricultural"...........??

My idea would be to remove them and place a large exhaust fan in the wall/door that the exhausts point at and duct it as needed from there.

That way:
1. No exhaust restriction.
2. You can see any flames or oil during the run.
3. May be able to observe FPT from control room.
4. Not as ugly.

Cheers Ian...

[smithy1]

Hi Alan,
I work for an aircraft engine repair company and I do a lot of work on the RR250-C20B, C30, C40 & C47 engines and I do the fuel controls for the C20B's & C30's. I can certainly get some info for you. The T63 is essentially the military version of the C20B. We use Mobil Jet-II in our engines. As long as the oil meets Mil-Spec...PRF-23699, Mobil 254 is also an alternative oil and meets the same specs.
I specialize in the Fuel Controls, Fuel Pumps and Power Turbine Governors. If you need any help or information, I'll do my best to help you out. I have access to all the latest manuals and test specifications etc...
I also have access to a Fuel Control/Fuel Pump test stand and a Power Turbine Governor Test stand if you need anything checked or calibrated.

Cheers,
Smithy.

[alan]

Smithy,
Thank you for that Mil spec. It's a relief to know I can contact someone who has experience with this engine. I was told that this engine should not need any maintenance done to it other than adding oil. I’ll have more questions for you after we solve the exhaust ducting and driveshaft setup problems and are close to running the engine.

Ian,
Unfortunately, the exhaust outlets of the engine point strait up. Actually if we had an exhaust fan in the ceiling then we could bring some ducting down from the fan and catch all the exhaust without creating any backpressure. I am going to look into that a little bit more.

[ashpowers]

I seriously doubt that the ducting has any chance of holding onto the exhaust ports.

If anything, make up some deflectors/air guides that will direct the exhaust flow in a rearward direction.

-Ash

[alan]

Update

The stove pipe has been removed from the Allison and we are searching for exhaust stacks with a 90 degree bend. A few phone calls have been made to try and get some unairworthy exhaust stacks donated, but nothing looks promising.

If anyone knows of a company that might have exhaust stacks for an Allison 250 (T63 or C20B), we would like to know about them.


While we search for the exhaust stacks, the second major issue needs to be addressed, which is the drive shaft alignment.


We were told that the output shaft of the engine, intermedite shaft and input shaft of the dyno have to be almost perfectly aligned. There does not seem to be a good way to measure the alignment of the shafts. If anyone knows a good method to aligning a driveshaft, we would really appreciate it if you could explain it to us.

Thank you.

[gidge348]

Hi Alan, there is a really good video on YouTube for a simple aligner made with a cheap laser pointer www.youtube.com/watch?v=qISvjpl65Z0

Because your shaft is quite short you could do the same with a plate bolted to one flange with a say 12 inch rod in the centre to just about reach the other flange.
Then 1. rotate the pin and bend as necessary to make it stay level then adjust the flange to be centred on the other flange.
Then 2. swap to the other flange and repeat.

Cheers Ian...

[alan]

Thank you Ian. Both those methods look doable. Ill post pictures when we try it.


Alan