Help Required with t58 (RR Gnome)

[Jetmotorcycle]

I’ve run the engine several times now with very mixed results.
I've run it up on the starter for about 25-30seconds until engine speed levels out, began ignition a few seconds before switching the fuel cock to on and then held until light up, the engine then starts to increase speed.
It runs very clean once it’s up to about 14500 but its not so good starting from cold. I’m not sure what may be a miss but I get a lot of yellow flame and heat.
I can only assume the yellow flame is caused by over fuelling and the heat because of the low volume of air flow (hot start). I’ve also seen small sparks and got ticking noises from the turbine stages.
As a precaution I removed both turbines, cleaned up any marks on the blade tips and shrouds and have rebuilt them, as luck would have it very little needed to be done.

My question to anyone that can help is, What can be done to adjust the excess fuel during start up. I have documents that cover engine parts but none on set-up???

Kind Regards

[barit1]

I would be wary of a few clogged fuel nozzles, leading to some nozzles being overfueled with attendant hot streaking. If it's coming up to speed at all then the fuel control is about right - it's a distribution problem.

What are you using to keep the PT shaft loaded?

[Jetmotorcycle]

Many thanks for the reply. I've started the engine but not opened the throttle as yet. Paying attention to the movement of the IGV and making sure they don't move. Been told this would be ok ?

What you say sounds very near the mark as the flames seem to be local to just one area. Top left hand. Do I need to open the engine up to sort this or can it be done by a fuel additive?

Thanks in advance.

[barit1]

I don't have any T58 details - just a general helo engine knowledge. Do you have any service manuals? If not, check on eBay etc.

[airborne_artist]

I guess this is ex a Wessex or similar? You might try asking on the mil forum, perhaps?

[BBJS]

Try a compressor wash. Whilst fluid is draining, check the igniter plug & make sure the igniter is set into the correct depth with the gasket & spacers, again the manuals and measuring tool will be required.

[Jetmotorcycle]

I have a genuine rolls royce customer manual it shows all the parts and systems, explanations included. Alas no service data at all.

airborne_artist, this is from a Wessex uk MOD surplus. I've had the exhaust housing turned to face upright, other than that its as was.

barit_1, checked on eBay but nothing much for the RR Gnome. The GE T58 has a different fuel system so i'm told so not gone down that route.

Should anyone be able to point me to service manuals, this would be a huge help.

Thanks all so far.

[sycamore]

r-r gnome

If you can find any info on it, an acceptable compressor cleaner used to be crushed walnut shells( not the nuts), which would act as a good abrasive to clean the compressor and the chamber and turbines to give a power recovery.Sometimes reqd. a couple of cleans. Wessex engines also could give off sparks from carbon deposits( a bit alarming at night).If you have access to an `intrascope` ,you may find build-up in the combustion chamber.Dont try hurling sand down the intake as it glazes over the internal cooling ducts and turbine blades!!!! We used to do comp washes with a mixture of water(de-ionised) and avtur at idle on Whirlwinds, but you require a very good mixer and fine spray(mist), otherwise ` Pooof-Poof,` and a melted turbine !!!!!!!Going a bit further, if you are using a Wx electrical H-P cock, they take about 2 secs to open/close; if checking IGV opening/closing speeds,a special H-P dump cock is used, or use a mechanical one( off a W-Wind), as when the engine surges, as it will as the IGV`s are locked open, the ordinary H-P cock will not close in time to prevent a burned turbine; as soon as it surges, the TIT will be around, and off the gauge, before you can say `POOF` !!!!!!BE CAREFUL... Syc

[BBJS]

The T56 was originally produced by General Electric, there website is www.ge.com. I would imagine they will have some information/ company rep who deals with/ has dealt with this engine.

BBJS

[barit1]

Originally Posted by BBJS

The T56 was originally produced by General Electric, ...

Methinks you have the T56 (Allison) confused w/ T58.

[Jetmotorcycle]

Not wishing to snub anyone as my knowledge of turbines is still very limited, I've posted some details.

General Electric T58/
de Havilland Gnome

In 1953 the U.S. Navy asked for a helicopter turboshaft to weigh 400 lbs and deliver 800 hp. GE's prototype T58 first ran in 1955 weighing 250 lbs and delivered 1,050 hp. Two T58s powered the first jet helicopter in the U.S., a modified HSS-1, in 1957. In 1959, the civil CT58 was the first jet helicopter engine certified by the FAA.
Production ended in 1984 but not before the T58 became the basis for the LM100 gas generator and was license built by de Havilland (now Rolls-Royce) as the Gnome, Alfa Romeo and IHI.

Although the engine is basically the same the fuel system and PT governor is very different on the Gnome version.

Thanks for showing interest in this topic.

[IcePaq]

Lean can cause unburnt fuel just as much as overfueling.

[IFHP]

Its been a long time since I played with a Walter or Gnome but a few first thoughts.( may be a bit confused with other engine systems )
Battery low voltage can lead to hot or hang starts.
Is PT output shaft loaded or locked govenor may try to overfuel ( I used to run Walters but always against rotorbrake )
Are you using Jet A1 or other fuels ?
Have you put any screening over intake ? ( you will need something )
Are your igniters set up correctly and giving off a really good spark.
Out of interest how are you going to harness the power of this thing?
Are you going to derate the engine like the RR 250 in the Y2K?
I must admit I have been having similar ideas if your name is a clue, but using a microturbine in a scooter ( a lot less power to soak up )
Have you tried any American sites, lots of people over there seem to be using similar turbines in tractors, boats etc.
Pm me if you need help anytime I live over the river.