Beechcraft Duke - Fuel flow

[toma60641]

Can anybody who has some time in this aircraft please post what fuel flow they get in the cruise? (And the associated power setting)

A typical cruise power setting is 30", 2500 RPM.

The Duke in our company seems to be giving questionable fuel flows.

Without going into the details, I'll just say that the 5 or so pilots that fly this arcraft, with their own techniques for setting the power and mixture, all get around the same fuel flow, and that this value is questionable.

To give further details would be to possibly influence the reply postings.

Thanks very much,
Tom

[Sharfted Groundhog]

If you know anyone in Air Nelson in New Zealand, ask them to ask Allan Belworthy. He used to fly the only Duke in NZ so will have all the hot gen on it. From memory he is still based in Nelson somewhere so you may be able to try the NZ White Pages Telephone Directory online for his number or try Air Nelson Ops....

Sorry about the limited help.

[I Fly]

20 000' in ISA 2500 RPM and 31" = 65% power @ 200kt. Supposed to use 139 LpH. Ours used 195 LpH. We thought fuel was stolen. Proved not to be the case. Checked the fuel control unit, the MP gauge, the Tacho. They could not fault anything, yet the fuel consumption was too high. We leaned to 50 degrees rich of peak.

[farrari]

toma60641, a good site that may help is www.beechcraft-duke.net click on Go to the Duke net

[toma60641]

Sharfted Groundhog, I fly, and farrari:

Thankyou very much for your replies. The reason I ask is because our Duke is giving high fuel flows, almost identical to the situation reported by "I fly".

Other research via the net, including the page pointed out by farrari, revealed 2 other Duke owners who also get the high fuel flow.

Incredible that the fuel flow should be 30% above the book figure, but that is appearing more normal, the more research I do.

Thanks again,
Tom

[cyclops camel]

Perhaps the 50 deg rich of peak EGT is the reason. Do the book figures reflect leaning further to reduce EGT on the lean side of peak?

[toma60641]

Hi cyclops camel,

Thanks for the reply.

Here is what the book says about leaning the mixture:

"If TIT limit not exceeded, lean to recommended fuel flow."

That is all it says. The TIT limit, by the way, is 900 degrees C and can only be checked if the TIT gauge has been calibrated properly, which is not necessarily the case in our Duke.

As can be seen, there is nothing stated about leaning with respect to EGT or TIT. There is no EGT gauge, only the TIT.

When the book says "... the recommended fuel flow" it can only be talking about the book figures.

Try to lean to the book figures in our Duke and you will experience severe rough running!

The fuel flow (digital), MP and fuel control units have all been checked out OK, btw.

Thanks again,
Tom Atkinson

[kickstart]

You have a serious problem. What does your Op's manual say to plan with, use that. 139 LPH sounds to good to be true though. What is your total hourly burn including climb and descent. Is this 139 just for the cruise?, do you lean on climb etc.