250-C20W higher burn rate

[bigsterm434]

Experiencing a 4-5 GPH higher burn rate than our other helos. Have swapped fuel control, bleed valve, and Shadin fuel flow transducer. No success thus far. Any ideas?

[Mikemv]

Get help from your Rolls Royce 250 Tech Rep or call Mike Underwood at RR.

[Gomer Pylot]

Have you checked the autorotation Nr? If it's not right, it can affect fuel consumption among other things. How do the N1 and TOT numbers compare to the other aircraft? How do the airspeed numbers compare? Has the torquemeter been calibrated with a deadweight tester?

 

That said, some engines just burn more fuel than others.

Edited October 24, 2010 by Gomer Pylot

[iChris]

Have you checked the autorotation Nr? If it's not right, it can affect fuel consumption among other things. How do the N1 and TOT numbers compare to the other aircraft? How do the airspeed numbers compare? Has the torquemeter been calibrated with a deadweight tester?

 

That said, some engines just burn more fuel than others.

 

Not enough information to pass-on anything but a personal experience with the Shadin. However, comparing N1 and TOT is an excellent way to start troubleshooting.

 

Had that problem with our Shadin unit. Shadin claimed the problem was that our unit was hooked to an existing fuel-flow transducer rather than installed as a system with a new transducer supplied by them. After talking to other users, there're other reasons for inaccuracy.

 

Things to check for are electrical noise. You may have to shield the transducer output wire. Installation variations may require you to reset the unit's K factor.

 

The fuel-flow transducer should be mounted upright, which is the position it was in when initially flow-checked and calibrated. Inside your engine compartment rather than on a flow bench, vibration, heat or even a trapped air bubble can change the K factor.

 

The Shadin installation manual doesn't cover resetting the K factor. To reset it, you need to measure your actual-vs. -Indicated fuel-burn and call the factory tech-support line and let them figure a new K factor and tell you how to reprogram the unit.

 

NOTE: The shadin's accuracy, they say, is around 2-5%. If you're talking about a Bell 212 at 100gals/hr you're in the ballpark. However, if your talking smaller ships like a Bell 206 at 28gals/hr you're off about 18%.

Edited December 1, 2010 by iChris

[Eric Hunt]

Park brake partially on?

 

Choke left OUT?

 

Mixture in Rich instead of Auto Lean?

 

But you already have the answer - check the auto revs. When it has been in service a long time, numerous blade trackings are solved by flying the low blade up, so the end result is smooth blades but excessive pitch, leading to increase profile drag.

 

Be careful when you roll off the throttle to check auto revs, the RRPM may continue to decay and you need to roll that throttle back on fairly smartly.

[Gomer Pylot]

Choke? Mixture? On a C20?

[Eric Hunt]

Gomer, you've seen the choke on a JetBanger - it's the knob on the dash in front of each pilot. I usually pull it out to hang my handbag on it. Sometimes there is a strange breeze around my feet when I apply the choke, haven't worked out why yet.

[Gomer Pylot]

Oh, you mean the keyring holder. That has other uses?

[500E]

Oh, you mean the keyring holder. That has other uses?

Key ring ? NO it is a choke the FI. told me along time ago Eric I have noticed that draft as well, strange