Slightly off-topic, but does anyone know what phase checks would run (ballpark) on a C501? I've read there's a low-utilization program for these. How does that affect phase timing, engine programs, etc.?

The low utilization program has no change with the powerplants.



http://www.baconaviation.com/citation-luip.html

Love a Pirep of your experience at CAE. Did you read mine about SIMCOM? I basically detail the whole check ride. Might be helpful. I assume it's two weeks? Price? Love the cafeteria at CAE.

Interesting situation related to fuel on a flight last weekend in the 550. The trip was near 1379 miles in length from Michigan to Arizona. Average head winds were 39 knots. Full fuel 5008 lbs. Can I make it? I want an 800lb or greater reserve on landing. Lots of good places to land in the Valley but from Flagstaff south the options are limited until you get to the valley so you better have your mind made up and be right passing Flagstaff.

Climbed to FL360 in 30 minutes burning 520 lbs in the climb. Set power to 100% N1 vs 104% max allowable. FMS says I am burning 920 lbs an hour (@ 325kts TAS)and will land with less than 400 lbs. Not nearly enough. Ok. It's early...let's see what happens down the road a bit.

There are three ways to determine fuel status in the 550. 1) Fuel gauges (tapes) 2) Fuel Totalizer 3) FMS (plan function think (JPI, Auracle)). Honestly, it is rare you make a flight so long that the differences (if any) between these three comes into play. Typically I choose the FMS. Halfway in (2.5 hours) it says I will land with 400lbs. Damn. I start really studying all the fuel indicators. Several thing jump out. The left engine, which is perfectly synced with the right is burning 70 Lbs/hr more than the right. Hmmm. Is that true? How would I know? After 2.5 hours that would mean I would have 175lbs less in the left tank than the right. The gauges indicate a balanced fuel load. So maybe that is a bad indicator. If so and the right and left are burning the same that means I would land with an additional 350lbs or 750 total. I could handle that.

The fuel totalizer agrees with the tapes that I have 200ish more lbs than what the FMS says. So I reset the FMS fuel quantity to match the fuel remaining on the totalizer and my reserve is right at 800. An hour later the same problem returns as the FMS still thinks I am burning more from the left than the right.

I use the text feature on the Satphone (think lifeline) and ask a buddy what he believes more the gauges or the FMS on his Ultra . Gauges is his answer. None the less I power back a little further to lessen burn. Damned if I can't remember the optimum long range power setting.

At this point I am at FL380 nearing the AZ/CO border. I am cleared to fly the Desrt2 arrival and have been given a descent to cross Shock at 12,000 at 250kts. The decent helps fuel burn and range but Shock at 250 hurts. Should I cancel and slow down to conserve? What if I can't get a clearance to enter Class B or SDL is so busy I have to delay?

It actually goes through my head that if the low fuel lights come on it means I have 169 lbs per tank or less. It that occurs do I shut one down and crossfeed? But cross feeding in a decent is NA per the POH. I wonder why? Even in an emergency?

Fuel gauges / totalizer still says 880 lbs.

On landing and roll out I deploy the Rev Thrusters only to see the low fuel gauge indicator flicker a couple times on the left. Seriously Is that just centrifugal force moving fuel away from the float? Wish I knew the answer!

On shutdown the totalizer says I have 870lbs. On refuel it turns out the left side took 2 more gallons than the right (far less than the FMS fuel burn imbalance indicated). Turns out there was 810 lbs on board. 60 lbs less than the fuel totalizer showed but 400lbs more than the FMS was showing. That is the difference between a stop and not. Fuel cost would have been $2-$3 more per gallon had I stopped.

Trip stats.

Distance 1379NM
Time 4.9 hours
Av GS 281 (40 knot HW average)
Avg Fuel Burn = 859 lbs/hr = 128 gal/hour
Fuel Cost @1.36/gal = $852

Lessons learned.

1) Know your airplane - which fuel indication is most accurate?
2) Know the optimum long range fuel power setting (or where to quickly find it)
3) Does the FMS fuel remaining function account for higher fuel burn down low ?
4) Why can't you crossfeed in a descent?
5) Is it normal to see low fuel indicator with thrusters deployed and 400 lbs a side?

Do you know these answers?

Wow, interesting observations and questions.

For us mere mortals: I've never run a tank dry on my Bo. On my flight down here to Texas from Iowa I decided this is the day to try it. 4 hrs flight, fairly good weather, 5.5 hrs of fuel, all is well.
I ran the left tank as low as I dared but decided to switch to the right one as I started my approach in to Decatur, TX! Fuel gauge showed essentially empty.
Sure enough, I added 36.5 gallons to that tank, meaning there was only 1/2 a gallon left.
Still had lots left in the right tank....

First, let me start by saying I really enjoy your narratives. They are fun and highly educational.

Regarding question #5, jet's don't have floats - they use capacitance systems which are significantly more precise. Putting my rusty and dusty engineer's hat on, here is an explanation of what might be going on. Disclaimer - I am not an expert in the subject nor do I know the intricacies of a capacitance system so if there is someone better informed, by all means please correct me:

A capacitance-type fuel-gauge system consists of a variable capacitor made of two tubes located in the fuel tank, a dielectric (the fuel), a reference capacitor, an amplifier and and the indicator (in the cockpit).

There is an electrical bridge which is continuously being rebalanced as a result of differences between the capacitance of the tank capacitor and the reference capacitor. The signal produced due to differences in capacitance are amplified and the fuel quantity is indicated. As fuel is consumed, the capacitance changes due to changes in the amount of dielectric (fuel).

My guess is that when the level is very low and you applied the thrust reversers, the electrical bridge between the two capacitor tubes and the fuel is lost as you stopped and the fuel moved forward.

You've recieved a good introduction to max range flying. The above questions and a number of other considerations are critical to landing under power.

Well, maybe, maybe not.

On my plane, the fuel GAUGE is done by capacitance, but the fuel LOW LEVEL WARNING is done by a float switch. This provides redundancy in case the fuel gauge doesn't work, I still have low fuel warning.

I checked the 550 AFM and POM and it doesn't say if the fuel low level warning is derived from the gauge sensors or by some separate system. I don't have a parts catalog to check that.

Mike C.

Something I try to do every time. 12,500-0 ( or something like that).

Well, maybe, maybe not.

On my plane, the fuel GAUGE is done by capacitance, but the fuel LOW LEVEL WARNING is done by a float switch. This provides redundancy in case the fuel gauge doesn't work, I still have low fuel warning.

I checked the 550 AFM and POM and it doesn't say if the fuel low level warning is derived from the gauge sensors or by some separate system. I don't have a parts catalog to check that.

Mike C.

If that is the case then that is a deficient AFM, but I assume upon closer inspection the information will be found there.

A cursory search provided the following on Citation 500/501/550/551 low level fuel warning;

L & R FUEL LEVEL LO Float switch in the respective tank indicates about 20 minutes fuel remaining for one engine in that tank at normal cruise power.

Yup my book from CAE says the low level light is from a float switch.

Also on the subject of proper fuel Managment to land under power.

So in the sim yesterday we had a Hydraulic failure. So we had to do the emergency gear extension. Followed by an engine failure. Followed by a double flameout on short final! It just wasn't our day. We did put it on the runway though!

Oh and another thing. One of our instructors told us that he had a flight crew from Isreal doing recurrent training there. And they would fly their CII for 7 hrs at a time. They would climb normally then set cruise speed with the AOA at .6 and that was it.

If we have time today I'm going to see what kind of TAS that gives you in the sim.

I remember that .6 on the AOA was max distance. Would love to know the IAS and TAS that would produce. Remember though that you won't make a crossing restriction at 250kts at .6

PS sorry you had so many failures in the SIM. That's quite unusual (said no one ever)

Very nice writeup Mark. Thanks for taking the time to share. For those not in turbines yet, those posts are very insightful.

I can't imagine you find $1.36 Jet A that often. Over the course of a year, what do you budget as an average cost / gallon? Obviously that can vary quite a bit from operator to operator based on destinations and cost at your home base...