GIV Tech Questions?

[Duderino]

I was flying a GIV, early serial number, into MCO late one night, and while talking with approach the right gauge went from 2000 pounds to less than 650 and turned amber. Anyone of y'all have any experiences with faulty fuel readings.

What reminded me to ask this was both of the IVs I am flying now are flying out of true. You can feel it, see it in the yoke, the trim tab during preflight is extended, and the trim wheels are countered about a quarter turn each. On a trip from FRG to Kiev Ukraine recently, we took of with 30,400 pounds, and landed with 3500. We had the power back at .77, got up high early, with the trip taking 9:20. Both planes also have a little dutch roll going on.

My concern is these other planes may have inaccurate fuel guages, leading to the added trim required, increased fuel burn, and dutch roll. If anyone can tell me of similiar experiences and there resolve, I would greatly appreciate it.

A different question I have is how do you turn the weather radar on while on the ground? The Red Book doesn't say.

Also The EPR Target bug(green carrot) disappears when flaps 10 are selected, and sometime between then and short final reappears. I can't remeber but it seems that it is there sometimes to help, and sometimes not. I have been able to deal without it just fine, but would like to know what its doing. The Red Book only says that when flaps and gear are moved, it disappears. Does it reappear once the new setting is computed by the slow processors?

Thanks for the help.
Duderino

 

[semperfido]

• fuel guages shouldn't do that....mx req'd
• having trim indicators not at zero is fairly normal as long as you have plane in trim. 9+22 is my max flight in g4 and it won't go too much farther. you probably climbed too soon.
• for radar on gnd hit stab 4 times
• from my feeble memory -crows feet go away when flaps 39 (it is normal not to have them on final app)

 

[Duderino]

Thank You very much.

 

[TIS]

I was flying a GIV, early serial number, into MCO late one night, and while talking with approach the right gauge went from 2000 pounds to less than 650 and turned amber. Anyone of y'all have any experiences with faulty fuel readings.

Gulfstreams are NOTORIOUS for less than perfect fuel readings in the mid quantities. Watch the quantity when you fuel and make sure you have the GALLONS, LITERS, or whatever on board. The plane is VERY accurate on fuel burn.

What reminded me to ask this was both of the IVs I am flying now are flying out of true. You can feel it, see it in the yoke, the trim tab during preflight is extended, and the trim wheels are countered about a quarter turn each.

Also doesn't sound that unusual to me. We've got 7 G-IVs and we've had a few problems on pre-buy inspections with the way planes have trimmed out. Most of the time we've gotten Gulfstream's aerodynamicist to figure things out - usually requires at least one re-rig of at least one control set. Sometimes stuff like spoiler float can cause what you're talking about and sometimes it's just bad rigging. I'd get it checked out.

On a trip from FRG to Kiev Ukraine recently, we took of with 30,400 pounds, and landed with 3500. We had the power back at .77, got up high early, with the trip taking 9:20.

Without knowing hte other specifics of the flight I'd have to say that this sounds pretty nromal to me. You flew a long ways and landed with just a little bit of fuel. Yup. Just about right.

Don't go any slower than that .77 you went then. The plane doesn't like AOAs less than .25 or so. Watch that when you LRC.

Both planes also have a little dutch roll going on.

Seen that before too. I've had it be the Y/D and it's been the stability augmentation system too. It could also be that .77 cruise you've been doing. Like I said, the plane don't like to go slow!

My concern is these other planes may have inaccurate fuel guages, leading to the added trim required, increased fuel burn, and dutch roll.

If the plane's got a fuel indication problem that leads to an imbalance that engenders a trim input you're gonna know it. At high weights, as you know, you're only allowed 400# of imbalance and there's a reason for it. Relatively small imbalances require some noticable correction. Large imbalances require large inputs. If your gauges are that far off you'll have a bigger handful than a silly gauge problem - LITERALLY!

A different question I have is how do you turn the weather radar on while on the ground? The Red Book doesn't say.

How you do this depends on what radar unit you have. The red book DOES indeed say how to defeat the forced standby mode but it's buried.

For the Primus 800 see Appendix B - B5. Unit returns to selected mode when the mode knob is moved to any other position or if the airplane becomes airborne.

For the Primus 870 see Appendix C - C9. Function is similar to Primus 800.

For the Primus 880 see Appendix D - D8. This is the one that turns back on if you press the STAB button 4 times within 3 seconds.

As an IMPORTANT aside - please note that in the TEST mode all three of these units are transmitting at full power. DO NOT test these units under any of the prohibited circumstances outlined in the limitations section or any other time that common sense says it would be a dumb idea to have the RT kicking out wattage.

Also The EPR Target bug(green carrot) disappears when flaps 10 are selected, and sometime between then and short final reappears. I can't remeber but it seems that it is there sometimes to help, and sometimes not. I have been able to deal without it just fine, but would like to know what its doing. The Red Book only says that when flaps and gear are moved, it disappears.

The red book says that the FLEX carrot and digital readout are removed when either the flaps or the gear are moved on takeoff. Makes sense.

Does it reappear once the new setting is computed by the slow processors?

Exactly! It can take some time but the autothrottles seem to have a good handle on what to do pretty much all the time.

Hope this helps!

TIS

 

[Chocks]

Dude...I've seen that in a GIV. Its not commen, but I've seen it a couple times. Have maintenance sump the tank on the bad side. If there is some water in the system, it will mess up the sensors. This is a cheap fix. If that doesn't fix the problem, you have to find the skinny maintenance dude and send him in the wing......harder fix.. Good luck. Gulfstream products are usually very solid...I'll bet once you nail down the problem, you'll never see it again.

 

[G4G5]

From my experience, whenever you see 650# in the hopper that is your actual condition. The amber "low fuel" message is set to trigger between 650-800#'s. The amber indicator has it's own dedicated fuel probe. It is NOT connected to the fuel quantity indicators. This needs to be addressed.

Typically what I have seen is the one way gravity fuel flow valves (similar to a one way dog/cat door) stick open. This allows the fuel in the hopper transfer out of the hopper and back into the wing tank. In turning on the amber warning message.

Have you ever come out to an aircraft, after it has sat for a few days, and noticed the fuel quanity in amber? this indicates that thoses doors/valves are week. if you turn the boost pumps on for a minute, they fill the hopper and all is normal.

Someone needs to get into the hopper and take a look around. I remembr the days when that someone was me.

 

[G4G5]

The EPR carrot disapears when you select flaps.

TIS is correct concerning the radar.

I would consider having GAC flt test take a look at the aircraft(s) in question the next time you are finishing up maint in SAV.

I would consider PM'ing GVflyer, he can answer your technical questions.

The FMS perf computer will get you introuble if you don't fully have it programed correctly a lot of guys use it to determine if they can climb to a higher altitude without fully having it programed correctly. All I can say is play with it until you fully understand how your inputs change you ability to climb.

It's been a year so my numbers may be off but you will get the point.
71,000 #'s = FL410
63,000 #'s = FL430
55,000#'s = FL450
Get use to your AOA indicator, for my aircraft flying .34 was near optimal, find yours. When I got down to around .32. It was time to consider climbing. I would look at the EPR indicator and use .1% as a rule of thumb for climbing. Example. If I saw 1.44 and then the perf climb epr was 1.54. I knew in most cases I had enough power to make my next step climb, while maintining my current speed. Then I verfied it by what I had programed in the FMS.

On long flights, like your flt to Europe, when you are keeping a close watch on your fuel. I would suggest prior to coasting out, updating the latest wx (winds and temps) for your enroute points. Then manually updating them into the FMS. The wind and temp you enter on the perf init page is blending that info with what you have programed or uplinked. The uplinked wx (from your flt plan agency) on a long flight can be 10+ hours old by the time you reach your destination.

 

[TIS]

The EPR carrot disapears when you select flaps.

Book DOES say selection of gear OR flaps.

Get use to your AOA indicator, for my aircraft flying .34 was near optimal, find yours. When I got down to around .32. It was time to consider climbing. I would look at the EPR indicator and use .1% as a rule of thumb for climbing. Example. If I saw 1.44 and then the perf climb epr was 1.54. I knew in most cases I had enough power to make my next step climb, while maintining my current speed.

This is better information than I gave you the first run through. The AOA I gave is for a GIIB/GIII - sorry - been doing some long haul stuff in those lately. It's a bit seared on my brain.

 

[TIS]

From my experience, whenever you see 650# in the hopper that is you actual condition. The amber "low fuel" message is set to trigger between 650-800#'s. The amber indicator has it's own dedicated fuel probe. It is NOT connected to the fuel quantity indicators. This needs to be addressed.

I agree - didn't mean to minimize the problem. But it is a different sensor and subject to other kinds of faults unique to that subsystem.

Having said that I'd follow the QRH for this for an AMBER FUEL LEVEL LOW L-R message. and oh, by the way, did you get a CAS message wit that indication? If not the DAU or FWC might also be involved. If you see it again, try switching either or both if you have time. It'll help isolate the problem. Been no comment on the results of doing that - namely, what did the STBY quantity indicator say? Did it agree with the EICAS reading.

Typically what I have seen is the one way gravity fuel flow valves (similar to a one way dog/cat door) stick open. This allows the fuel in the hopper transfer out of the hopper and back into the wing tank. In turning on the amber warning message.

I thought this was an early problem on the GV that had to do with fuel gelling. Hopper empties out due to consumption and is not refilled by gravity because fuel is too thick to move. Oh well, I suppose anything's possible - there's a lot of movable stuff in that wing.

TIS

 

[Duderino]

For the Primus 880 see Appendix D - D8. This is the one that turns back on if you press the STAB button 4 times within 3 seconds.

As an IMPORTANT aside - please note that in the TEST mode all three of these units are transmitting at full power. DO NOT test these units under any of the prohibited circumstances outlined in the limitations section or any other time that common sense says it would be a dumb idea to have the RT kicking out wattage.


The red book says that the FLEX carrot and digital readout are removed when either the flaps or the gear are moved on takeoff. Makes sense.



Exactly! It can take some time but the autothrottles seem to have a good handle on what to do pretty much all the time.

Hope this helps!

TIS

The Book pages I have are different, probably because Simuflite Gave it to me and its really old. The Flex EPR Target Note on my page A28-1146-097, 5-9, says The FLEX EPR target is removed when either gear or flaps are moved. And thats all I can find. Thanks for the tips on this. About the Radar, the wording here seems to be written by a Lawyer, and is confusing. However, sure enough it is right there, and I read that section three times. Duh.

Have you ever come out to an aircraft, after it has sat for a few days, and noticed the fuel quanity in amber? this indicates that thoses doors/valves are week. if you turn the boost pumps on for a minute, they fill the hopper and all is normal.

I have seen this but the indicated amount is more than between 800 and 650. I remember seeing 1800 to 2000 pounds indicated in each wing and the numbers and boxxes in Amber. Didn't know what was going on. This was on the serial number that had the problem.

The EPR carrot disapears when you select flaps.

TIS is correct concerning the radar.

I would consider having GAC flt test take a look at the aircraft(s) in question the next time you are finishing up maint in SAV.

I would consider PM'ing GVflyer, he can answer your technical questions.

The FMS perf computer will get you introuble if you don't fully have it programed correctly a lot of guys use it to determine if they can climb to a higher altitude without fully having it programed correctly. All I can say is play with it until you fully understand how your inputs change you ability to climb.

It's been a year so my numbers may be off but you will get the point.
71,000 #'s = FL410
63,000 #'s = FL430
55,000#'s = FL450
Get use to your AOA indicator, for my aircraft flying .34 was near optimal, find yours. When I got down to around .32. It was time to consider climbing. I would look at the EPR indicator and use .1% as a rule of thumb for climbing. Example. If I saw 1.44 and then the perf climb epr was 1.54. I knew in most cases I had enough power to make my next step climb, while maintining my current speed. Then I verfied it by what I had programed in the FMS.

On long flights, like your flt to Europe, when you are keeping a close watch on your fuel. I would suggest prior to coasting out, updating the latest wx (winds and temps) for your enroute points. Then manually updating them into the FMS. The wind and temp you enter on the perf init page is blending that info with what you have programed or uplinked. The uplinked wx (from your flt plan agency) on a long flight can be 10+ hours old by the time you reach your destination.

All of the information given here in this thread is why this board Kicks Ass. I have been flying with a few Captains, that never seem to help me out. This information is priceless and is only handed down. Either these guys really don't like me and don't want me to learn anything useful, or they don' t know chit. I think its both.

 

[G4G5]

I have seen this but the indicated amount is more than between 800 and 650. I remember seeing 1800 to 2000 pounds indicated in each wing and the numbers and boxxes in Amber. Didn't know what was going on. This was on the serial number that had the problem.

BINGO!
The Amber indication comes from the dedicated low level probe in the hopper. If the aircraft sits the fuel will try to seek it's own level, the hopper will try to stay full. If the valves in the bottom of the hopper do not close they will allow the hopper level to decrease. Hence the amber indication and the fuel quanity greater then 800 lbs.

 

[Senior_Citizen]

Either these guys really don't like me and don't want me to learn anything useful, or they don' t know chit. I think its both.

Hey, these guys are nuts, what lack of common sense, we have a gold rule, no mater the position of a crew member (Capt. or F.O.) both must to share all the data about the plane and the trip. The F.O. isn't a luxury or imposition of the unions, the F.O. must be fully capable to maneover the plane and to follow a F.P. in case of a Captain inhability by disease (infart a.e.), or accident, we firmly don't support the "F.O. only need to knows the necesary to land in a emergency", some guys don't understand that policy, we just don hire they.

Hey Duderino, do you have plans to look for a new position on the next 12-18 months, we could have a vacant for a F.O. or maybe a Capt, (for our G450 wen it arrives, or maybe before on a dry leased G4), forget the salary numbers I previously conmment.

 

[Duderino]

I am looking everyday for a new job. I just don't want to move sideways. Looking more for 91 work now. Tired of 135 stuff, it is crazy. After this post, now I realize our planes don't go to Savannah, but instead PrivateSky at RSW. I will send a PM to get your contact information, Thanks.

Duder

 

[fokkerjet]

Been out of the airplane for several years, but...

From the SPZ-8400 manual.... "The display digits are normally white but turn amber when the fuel level low signal is received from the DAU. The whole window turns amber when both sides indicate a low fuel level" A DAU failure should be indicated by amber dashes, but we all know how that goes......

If this is happening when you are first powering up the airplane, I'd say the DAU isn't 'booting" up correctly. I've seen this on the GV, and the F2000 and Fokker for that matter, and by "going black" again with the airplane, then powering up all over again, it corrects the problem. In flight, I'd suspect some sort of wiring issue first; something happening between the probes and the DAU, or the DAU itself. All the problems we've had with fuel gauges have been wiring related; nothing in the tank but in the avionics rack.

So many computers in airplanes now, if one doesn't boot correctly, or in sequence, it throws everything else off.

 

[GVFlyer]

Fuel Quantity Mnagement System

From the SPZ-8400 manual.... "The display digits are normally white but turn amber when the fuel level low signal is received from the DAU. The whole window turns amber when both sides indicate a low fuel level" A DAU failure should be indicated by amber dashes, but we all know how that goes......

If this is happening when you are first powering up the airplane, I'd say the DAU isn't 'booting" up correctly. I've seen this on the GV, and the F2000 and Fokker for that matter, and by "going black" again with the airplane, then powering up all over again, it corrects the problem. In flight, I'd suspect some sort of wiring issue first; something happening between the probes and the DAU, or the DAU itself. All the problems we've had with fuel gauges have been wiring related; nothing in the tank but in the avionics rack.

So many computers in airplanes now, if one doesn't boot correctly, or in sequence, it throws everything else off.

Years back, we had a problem with Mexicali co-ax.

GV