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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 19 Aug 2021, 17:41 
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I ordered 120 gallons of fuel from my FBO on Sunday mid day. Only received 730 pounds per fuel gauge on Proline.

730/6.7 = 109 gallons. It was warm in Charlotte.
730/120 gallons would be 6.083 lbs per gallon

Does JET-A fuel density vary this stinkN much when warm?

Back from Rochester NY yesterday over remnants from Fred.

FL360 still IMC and ISA+11 Last 2,000 feet took about 6 min and ended at 160 KIAS
Sat there a bit remembering sumpN about telling wife we would almost never be in clouds in cruise anymore.

Can I limp up to FL380?
Was just over 200 KIAS when I began climb to FL380.
Made FL380 in less than 4 min ending at 170KIAS
ISA+5

352 knots True before long and on TOP

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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 19 Aug 2021, 21:00 
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Username Protected wrote:
I ordered 120 gallons of fuel from my FBO on Sunday mid day. Only received 730 pounds per fuel gauge on Proline.

730/6.7 = 109 gallons. It was warm in Charlotte.
730/120 gallons would be 6.083 lbs per gallon

Does JET-A fuel density vary this stinkN much when warm?



Instrument error? How do these birds measure the weight of fuel anyway? I must have been a little distracted during that portion of class.


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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 19 Aug 2021, 21:25 
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There should be a temp compensation probe in the fuel system I would think.


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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 19 Aug 2021, 21:36 
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Temp of fuel makes a difference on the gauges. Doesn’t seem to impact range though, which doesn’t make sense. I have noticed late in flight I tend to gain back the 80lbs or so I lose topping off on a hot day.

Brad - don’t you have an Avanti II? Thought those did better at altitude. I have found anything above isa10 and it slows down a good bit over fl350.

I cruised at fl400 the other day.

ISA +5 there but ISA+10 at FL380 and below so it worked out speed wise.

Fuel burns and noise are non existent at FL400.


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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 19 Aug 2021, 22:44 
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Username Protected wrote:
I ordered 120 gallons of fuel from my FBO on Sunday mid day. Only received 730 pounds per fuel gauge on Proline.

730/6.7 = 109 gallons. It was warm in Charlotte.
730/120 gallons would be 6.083 lbs per gallon

Does JET-A fuel density vary this stinkN much when warm?



Instrument error? How do these birds measure the weight of fuel anyway? I must have been a little distracted during that portion of class.


This is a complicated subject:

Capacitance systems measure the weight of the fuel according to its dielectric constant and the amount of probe submergence, calculating for the amount of fuel each probe measures.

Most, or all, capacitance systems compensate for temperature by having a dedicated compensator probe or a normal probe that is almost always completely submerged. If the reading of the completely submerged probe is say, 95% of complete submergence nominal, this is applied to the entire system measurement.

Where it gets trickier is variations in the dielectric constant versus density relationship at a given temperature. Published fuel property information states that this can reach 5-10%, although I have never been able to find survey information that shows how common this is. We ran into this on a flight test to Bolivia but didn't have anything to take a fuel sample for later analysis. The flight crew wondered if we got JP-4 instead of JET A. Some/many airliners, especially newer and/or longer range ones, have a separate device called a densitometer to correct for this. I don't think they are very common in general aviation turbine aircraft.

Edit: I incorrectly said that dielectric versus density variations could cause 5-10% error. This error exists, but is much lower. What I was referring to was 5-10% discrepancy in full fuel indicated weight when we did not know density or type of fuel or other possible unusual fuel properties, and therefore did not know how much of the discrepancy was due to fuel and how much to indication. I should also add that even a densitometer does not solve all problems, due to stratification, such as warm fuel loaded on top of cold fuel in the bottom of the tank where the densitometer is installed.

Last edited on 20 Aug 2021, 00:13, edited 1 time in total.

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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 19 Aug 2021, 22:47 
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Username Protected wrote:
I ordered 120 gallons of fuel from my FBO on Sunday mid day. Only received 730 pounds per fuel gauge on Proline.

730/6.7 = 109 gallons. It was warm in Charlotte.
730/120 gallons would be 6.083 lbs per gallon

Does JET-A fuel density vary this stinkN much when warm?



Instrument error? How do these birds measure the weight of fuel anyway? I must have been a little distracted during that portion of class.


This is a complicated subject:

Capacitance systems measure the weight of the fuel according to its dielectric constant and the amount of probe submergence, calculating for the amount of fuel each probe measures.

Most, or all, capacitance systems compensate for temperature by having a dedicated compensator probe or a normal probe that is almost always completely submerged. If the reading of the completely submerged probe is say, 95% of complete submergence nominal, this is applied to the entire system measurement.

Where it gets trickier is variations in the dielectric constant versus density relationship at a given temperature. Published fuel property information states that this can reach 5-10%, although I have never been able to find survey information that shows how common this is. We ran into this on a flight test to Bolivia but didn't have anything to take a fuel sample for later analysis. The flight crew wondered if we got JP-4 instead of JET A. Some/many airliners, especially newer and/or longer range ones, have a separate device called a densitometer to correct for this. I don't think they are very common in general aviation turbine aircraft.

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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 19 Aug 2021, 23:03 
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Wow, that is complicated! So does the capacitive element measure the fuel level, multiplied against a known geometry of the tank to calculate volume, then the temperature compensator modifies the density variable to calculate mass?

The theoretical dielectric constant temperature variation could introduce an error in level sensed?

All that said, mine seems pretty darn close.


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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 19 Aug 2021, 23:12 
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Bill, well said and that bears repeating. :D

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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 20 Aug 2021, 12:49 
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Username Protected wrote:
I ordered 120 gallons of fuel from my FBO on Sunday mid day. Only received 730 pounds per fuel gauge on Proline.

730/6.7 = 109 gallons. It was warm in Charlotte.
730/120 gallons would be 6.083 lbs per gallon


This was a real good thread.
viewtopic.php?f=4&t=190703&p=2798805&hilit=fuel+temperature+density#p2798805

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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 20 Aug 2021, 17:00 
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Username Protected wrote:
I ordered 120 gallons of fuel from my FBO on Sunday mid day. Only received 730 pounds per fuel gauge on Proline.

730/6.7 = 109 gallons. It was warm in Charlotte.
730/120 gallons would be 6.083 lbs per gallon

This was a real good thread.
viewtopic.php?f=4&t=190703&p=2798805&hilit=fuel+temperature+density#p2798805

Yes, fuel density (SG) varies with temperature, airport elevation, pressure, etc. But 6.083 does not seem possible.

Brad, if not already stated, I always ask the fueler to write down the SG (density) on the fuel slip that he signs. And keep the fuel slips with my W&B records.

In section 6 of the King Air POH/AFM there is an important table with fuel weights and moments, values range from 6.3 to 7.1 Lb/Gal.

Attached is my working copy of the table with metric annotations. Highlighted in yellow is the 6.5 Lb/Gal column that I usually find where I fly. With Full Fuel (539 Gal, 2040 Lit volume), there is a 107 Lbs difference with the "normally" used 6.7 Lb/Gal.

Please login or Register for a free account via the link in the red bar above to download files.


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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 11 Sep 2021, 09:28 
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I finished my FSI recurrent training yesterday. The week of sim flying was some of the hardest things I've ever done.

It's been something of a cluster for a year. I was advised (not by FSI) to do in airplane training then the recurrent at FSI instead of the full 2.5 week initial course. I did the in aircraft which was a piece of cake. And I've trained twice since then in 11 months of flying on the usual stuff including engine out, partial panel, SE approaches, etc. But when I went to FSI in October I got exposed to Covid on the way down and had to bug out. Then I went back and got the flu after the first day of ground school and had to bug out.

So, for the last year I've been flying, at my insurance company's wise dictum, with a copilot. And I've learned quite a bit from those experienced captains. So, with 180 logged hours, including about 15-18 doing training, I headed off.

I won't describe what they do to you. I think everyone knows that you are going to do a full suite of procedures, most hand flown, many SE, always in IMC and usually at night and get to see a whole bunch of failures along the way. Check.

Here's what surprised me, sobered me and committed me:

1. EFATO is waaay different than pulling the throttle back at altitude to simulate failure. I had no idea how hard I needed to push on the rudder. And you have no time or margin to work with. It was sobering to see how slowly the vaunted P180 climbs on a 20 degree day, at sea level and gross. But, after a bunch of V1 cuts I know I can do it. I certainly didn't the first time I tried which is where I'd have been if I had never gone to sim school. It makes a hell of an impression when you crash the sim, the screen goes red and you just sit there for 5 minutes listening to "BOOM" over and over again. Now, I just have to pray there is no windshear on takeoff or that I have fly a complicated departure in the mountains with EFATO. The first is impossible and the second unthinkable. Check.

2. My instrument scan sucked. A couple of years of Covid flying to VMC destinations basically killed it. It held up ok hand flying a piece of cake twin engine approach. But of course you don't see much of that in the Sim. I need to learn to manipulate the cockpit the way Stevie Wonder plays the piano. I can do it sitting in the cockpit in my hangar.
But under stress and pressure it broke down. It's a highly perishable skill. Check.

3. Stress has to be managed and when you're not used to managing it you make a lot of unforced errors. Mine almost always had to do with reacting too fast. Clearly I need more training to just learn to slow down. Check.

4. I'm not as young as I used to be. I'm 63. What I had demonstrated for me daily was that my physical and mental endurance isn't as good as it was 10 years ago. That has lots of implications for me including when, where and how I fly. Sobering. Humbling. Useful. Check.

5. Proline 21 is a great system and not too hard to use in an emergency. My biggest issue is why the heck does the roll pointer point left when you're turning right. I'm still not used to that and when the stress load is really high it sucks a lot of bandwidth just trying to deal with it. And that damned Flight Director is awesome until it starts lying to you and you'd better know when that is and what to do about.

5. In aircraft training for an airplane as complex, slippery, small winged and highly powered as this one is just isn't good enough. How do you possibly, and safely, fly through 50 knot windshear at a high altitude airport? Load up one wing, but not the other with ice (not hard to do but essentially impossible to recover from - so don't get there)? V1 cuts? SE approach and missed with cascading failures in IMC at night? Recovery from low altitude stalls (yeah I know you're not supposed to do that - but I did - shocked hell out me)? Oh, how about dual generator failure at FL40 where you have basically nothing but the back up instrument and compass, no gear, no flaps, little braking and 30 minutes before it all goes? And the quality and difficulty of training varies. Having done sim schools for the TBM at another school I can tell you that FSI is just better. Much. And much more challenging.

This was 10 of the hardest hours of my life. I passed. Now I'm insurance qualified to fly SP. But I'm not going to. Having a copilot is just cheap life insurance. It's been a PITA to line up guys. And it's not cheap. And while I think I'm a good pilot I'm not good enough to take anyone else's life in my hands by myself. I need more training, and more often, and I'm going to get it.

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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 11 Sep 2021, 11:02 
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Tony,

Welcome to the choir.

My first sim training was at FSI 20+ years ago: Citation V Ultra initial. Prior to this first jet gig, I had been flying night freight in 310s and then charter in a Cessna 402 and King Air 200. I thought I was a decent pilot.

That first sim experience gave me the dreaded "there but for the grace of God go I" feeling. I came to the realization that being able to recite checklists and being able to deal with pretend training emergencies in the real airplane while safely at altitude is merely training theater. Once someone is in a sim dealing with emergencies at low altitude and in weather - it becomes clear that actually feathering propellers and closing firewall shutoff valves is a whole different ballgame.

In my first FSI training, I remember one sim session during which I had successfully handled an engine failure/fire: shut it down, closed the firewall valve, blew the bottle, flew the airplane out of whatever predicament it was in. With that over and us established on a peaceful vector back to the airport, the instructor said that the engine had been miraculously fixed and that we should restart it. I was so relaxed and this seemed like a gift from heaven that we could have the engine back. I pulled the restart checklist. One of the early items was to open the firewall valve. I had been trained to confirm the correct L or R side when closing the firewall valve, but it never occurred to me that I should waste time on this when merely opening a firewall valve. Due to complacency and to some quirk in the way the Citation fire extinguisher lights glow when one bottle has been blown, I pushed the wrong firewall valve. I shutdown our only engine. My humanity - long apparent to everyone else - became clearly apparent to me. That experience has profoundly affected the way I fly.

I wish that every pilot would have the advantage of realistic Level D sim training - and the earlier the better. This training is desperately needed in the piston world - but pilots typically have to wait until they are in the safer turbine world in order to get it.


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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 11 Sep 2021, 17:58 
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Tony, great write up. Some of the airplane characteristics determine which is better, Sim or in airplane. Dual engines most definitely require the workout that you mentioned.

Would you feel more comfortable in a jet on efato?

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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 11 Sep 2021, 18:09 
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Good write up Tony, thanks for sharing.
Username Protected wrote:
some attitude indicators have sky pointers instead of a roll index to show angle of bank. They are called sky pointers because they always point straight up, at the sky. If, for example, you are in a 30-degree right bank the sky pointer will be 30 degrees left of the center mark. Most of us are used to the so-called roll index indication that is 30 degrees to the right in a 30-degree banked right turn. The roll index is common in light airplanes, but the sky pointer is the norm in jets.

https://www.kellymfg.com/images/Fixed%20vs%20Movable%20pointer.pdf


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 Post subject: Re: The definitive Piaggio P180 Avanti thread.
PostPosted: 11 Sep 2021, 18:32 
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I think OEI is all about what you are used to. Mu2 required full strength boot. Piaggio about half of what mu2 required. I am not sure how the Piaggio gets more benign. Step on the ball. Fly away. Going to FSI soon for recurrent and will report back. Can’t imagine a jet requires a whole lot less foot.

The age thing is interesting. I am a very fit 41yo. I know a lot of 60-70 year olds. Given relative sports performance, even for a 60yo friend who was a world famous athlete 30 years ago, once people pass about 55 performance drops significantly. I do wonder if training can correct for that, or how much? While flying isn’t entirely physical, the sports reaction times I have observed on 60+ yo males is not what I would call great. Makes me wonder what I will think when I get to that point. Watching my dad over the years has often reminded me of the quote - your mind is writing checks your body can’t cash. And before people start flaming away - I am sure there are exceptions, etc. Just an observation that age is no joke on the risk curve.

I do think all these complex turbine planes require weekly flights just to keep the mental autopilot sharp. Knowing where to reach without thinking seems to be a function of reps more than anything else.


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