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bönan

Q400 Cruise settings

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I've recently started flying the Q400 more regularly and I'm really getting the hang of things now. I found it hard to land in the beginning, but after realising I need to keep power on all the way down I have improved my landings a lot. One thing still bugs me though: power settings in cruise.

 

The 850 RPM setting is the suggested one for cruise as far as I understand things, but this actually yelds a higher fuel flow than 900 RPM. Also, as I understand it, the power levers should be all the way forward from the start of the takeoff roll until TOD. Also, at this power setting, I get a cruise speed of 220 KIAS, or 336 KTAS, at FL260 which is a bit short of the promised 360 KTSA. Fuel flow varies between 1010 and 1030 PPH without any power changes. Why is that?

 

So, could someone with more experience shed some light on this, and which settings results in best cruise speed, best range etc.

 

Best wishes,

Björn Lillpers

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At Intercity, our cruise profile is as follows:

Cruise and descend at 850 rpm and Vmo-20, this gives 900 kg/hr (roughly 87% NL). Vmo-10 will give you a fuel burn of around 1000 kg/hr but you may only use this profile if you are behind schedule.

If you have a strong tail wind, you can cruise at about 210kts indicated, Vmo-40, about 84%NL).

You should cruise at FL210-250 on almost all flights; avoid cruising in the teens as fuel burn goes up and TAS goes down a lot.

The use of lower RPMs is to reduce noise, not just fuel flow. Some airlines climb at 850 rpm for that reason.

 

I pull the power levers back in cruise to match the figures I quoted above, the rating detent is typically used from takeoff to ToC with FADEC managing thrust/torque. If you need maximum possible TAS, you can cruise lower (around FL190) at Vmo-5 but there is a big fuel burn penalty for the small TAS increase.

 

I should point out that most Q400s aren't equipped with passenger oxygen supplies so can't go above FL250.

 

20 lbs/hr variance is not significant (less than 2%), possibly caused by FADEC adjusting things or slight changes in atmospheric conditions and wind.

 

There's more information regarding Q400 cruise performance at http://majesticsoftware.com/forums/discussion/431/cruise-speed

 

I know I've not answered everything you asked, but I hope this post has helped answer some of them.

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Also, as I understand it, the power levers should be all the way forward from the start of the takeoff roll until TOD

 

keep the power fully on until top of climb only!. ckyliu covered most of it, but to show another way to determine it, in my case when i am flying i set throttle power during cruise according to the fuel plan i get from simbrief. 

 

the brief shows the ideal/planned KIAS and KTAS for each waypoint and i adjust my throttle to get close to that. usually that means cruising around 210-230 knots with a power setting of around 52-54%... when under heavy turbulence, reduce to 210 knots which usually ends up around 46-48%. those speeds provide a nice balance of range and brevity. simbrief also has a long range cruise profile that is closer to 200 knots and adds a few hundred nm to the max distance.

 

generally the cruise level it assigns is FL240 or FL250, although on legs that are shorter than an hour it can set it a bit lower, down to maybe FL18 or 19 maybe.

 

another post i saw about this issue from a RW pilot said their airline's typical cruise speeds were around 234 knots. it's fairly dependent on the routes and schedules etc.

 

cheers,

-andy crosby

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The OP is correct in that the 850 cruise setting should give you a lower fuel flow figure than 900, but as I understand it this is an unavoidable workaround to get the Q400 to consume fuel accurately inside FSX.

 

In terms of where you put the power levers - the SOP for the European airline featured in our Q400 training course is Max for takeoff and landing (although you can also select 'RDC LDG' and then quickly move the levers to the Max position, which leaves the props at 850 but will put them to max automatically in case of a go around) 900 from accel alt until top of climb and then 850 all the way down until the landing checklist.

 

You can of course finesse the power levers throughout the cruise but as long as you've not got a stonking tailwind and/or are fairly light, you should be able to just leave them where they are and let the FADEC look after things.

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