Allison Model 250 C20 Turboshaft Operational range

[Onemorechance]

Hi,

Any RR or Allison engineers or others that could help me with these 2 questions?

1. I know that in a MD-520 Helicopter the engine (Allison Model 250 C20 Turboshaft) is installed with engine axis under 45° compressor up, while the same engine is installed in many other helicopters and aircraft engine axis more or less 0° .
Besides the fact that it would not be recommended for dirt ingestion, do you think that the engine can also be installed and operated 45° compressor down?
If so, it would be possible to use this engine for certain VTOL applications where the engine is tilted over an angle range of 90°.

2. If the above question does not answer with a yes. Say I install the engine with engine axis in transverse direction, do you think it is capable of operating in a rolled (I mean rolled about engine axis) attitude of +45° through -45°?

Even though I would be so happy if one of these two questions would be answered with a yes, do not say yes if you are not really sure.

Thanks.

OneMoreChance

 

[aviat]

Why don't you direct your question to the technical support people at RR or Allison?

 

[Stache]

I just happen to over see a Rolls-Royce overhaul facility in Oakland, CA that works on the 250 engine. If you would like to speak with their engineer staff telephone at (510)613-1000 and request the lead engineer. The engineer staff will put you in contact with the right people in the company to answer your questions.

Stache

 

[Onemorechance]

Stache,

Thank you for the phone nr. I will do that.

OneMoreChance

 

[Onemorechance]

I think I need to close this thread by adding what I know by now on this question.
As I asked Rolls Royce Customer Services about this I had the following information:

The Allison Model 250 C20B engine (420SHP MaxTO) as certified, is capable of starting, operating continuously and stopping when mounted with the engine centerline at any attitude from 75 degrees above horizontal (compressor up) to 30 degrees below horizontal (compressor down).
The oiling system is designed to cope with this attitude range, except the oil tank, which is provided by the airframe and is not part of the engine. But a flexible pick-up tube or an aerobatics oil tank would solve that problem.