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Biz Jets Flex or Derate Thrust settings

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Biz Jets Flex or Derate Thrust settings

Old 3rd Jul 2012, 08:37
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Biz Jets Flex or Derate Thrust settings

A question I was asked today

Do midsize Bizjets, Citation X, Sovereign, Falcons, Challengers, Gulfstreams etc use reduced thrust (assumed temp and.or fixed derate) for light weight takeoffs.

In an aircraft doing 300 odd hrs a year, is their any benefit.

Im well versed in the advantages of flex and derate on the heavy iron but wasnt able to anwer the question re bizjets.
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Old 3rd Jul 2012, 08:40
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Gulfstreams do Flex thrust takeoff's calculated by the FMS.

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Old 3rd Jul 2012, 08:49
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So does the GLEX. Useful, seeing as on many/most takeoffs we aren't up anywhere near MTOW and therefore rather over-powered. Procedure not used by many operators though, from what I gather.
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Old 3rd Jul 2012, 09:37
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Citation Sovereign: no procedures available for that,

And I just love to depart with 1 dude in the back and 3000lbs of fuel, no baggs...that when the plane really performs...when 6000fpm climb won´t keep ya below 250KIAS...

Sometimes I wish we`d had an F-4 instead of the Cessna -> way more fun for me!
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Old 3rd Jul 2012, 10:38
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We use Flex on the G550 wherever possible now. No reason not to. Gulfstream have published clear guidelines and the company encourage us to do so, but its entirely at our discretion.
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Old 3rd Jul 2012, 12:27
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Citation Sovereign: no procedures available for that,

And I just love to depart with 1 dude in the back and 3000lbs of fuel, no baggs...that when the plane really performs...when 6000fpm climb won´t keep ya below 250KIAS...

Sometimes I wish we`d had an F-4 instead of the Cessna -> way more fun for me!
Yep bummer when 30 degrees nose up just wont slow you down........Flap 7/2400lb/0 Dudes/Empty Galley! - Positioning for a reweigh
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Old 3rd Jul 2012, 15:05
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No, Citation X.
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Old 4th Jul 2012, 11:01
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Global 5000 - yes
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Old 4th Jul 2012, 11:46
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In short, Bombardier, Dassault, Gulfstream, yes. Cessna, no. You can always pull the loud levers back in the climb though!
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Old 4th Jul 2012, 12:33
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Bombardier
Not the 300 IIRC.
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Old 4th Jul 2012, 12:37
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There's always exceptions, and you generally have to pay extra to use it anyway!
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Old 4th Jul 2012, 14:43
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The point of doing it on a corporate jet? Your on a long runway, light, by yourself, and you don't want to climb like an F16...sure I have done it in jets that will come off the ground in 1500 feet on a 10k runway. Now how many here fly by themselves with out pax back from maintenance?

Otherwise what's the point? You can't trend monitor your engines out to 30k like the airlines, a corporate jet engine is coming off in say 5k whether you baby it or not..so it's kinda stupid to be flying a 25 million dollar plane to the fence and pulling up because you think your saving on overhaul costs.

Honestly, this is the kinda crap that happens when you hire buddies and pals off the bottom of the resume pile...just puts lives at risk and our reputation suffers for it.

:

Last edited by Sillypeoples; 4th Jul 2012 at 14:46.
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Old 4th Jul 2012, 16:21
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New business planes offer on condition maintenance for engines same as for airliners, for those i would guess that reducing makes sense. For those business jets that are derivates from airliners (BBJ, ACJ etc) it is a given anyway.
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Old 4th Jul 2012, 17:49
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so it's kinda stupid to be flying a 25 million dollar plane to the fence and pulling up because you think your saving on overhaul costs.
Welcome back SSG, how many times must we tell you that we dont pull up at the fence.......

this is the kinda crap that happens when you hire buddies and pals off the bottom of the resume pile...just puts lives at risk and our reputation suffers for it.
And your next pet hate will be about putting 200 hr pilots in right seat... You are getting too predictable

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Old 4th Jul 2012, 18:15
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Otherwise what's the point? You can't trend monitor your engines out to 30k like the airlines, a corporate jet engine is coming off in say 5k whether you baby it or not
The HTF7000 on the Challenger 300 is OC, not a fixed TBO...or HSI and that is a growing trend...
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Old 5th Jul 2012, 20:14
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Emirates used flex at Melbourne some years ago IIRC and nearly caused the worst air disaster in Australian history.

Speaking of Australia, one airline, who had never had a haul loss decided it was beneficial not to use reverse thrust, even on a wet runway. They came to grief.

We all tend to be getting away from the basics in aviation today. When we did ab initio training, did we reduce the power on T/O?? Hell no. Then why do it now? Don't try and reinvent the wheel, as it has all been done before.

Risk management is the term they use today i believe. Then manage it.

K.I.S!!

Last edited by doubleu-anker; 5th Jul 2012 at 21:30.
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Old 6th Jul 2012, 04:28
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d-a, the problem at Melbourne was not the use of flex but the incorrect weight loaded into the FMC. The problem was rectified by judicious application of power which was almost too late but did finally get the beastie off the ground after causing some havoc with runway lights and aerials.

As for QF1, there were many other problems that led to that little overland excursion other than merely the use of reverse thrust or not. To that airlines credit they learned very quickly.
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Old 6th Jul 2012, 11:44
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"d-a, the problem at Melbourne was not the use of flex but the incorrect weight loaded into the FMC. The problem was rectified by judicious application of power which was almost too late but did finally get the beastie off the ground after causing some havoc with runway lights and aerials."

Put simply, reduced T/O power/Flex, was calculated, using the FMS.


"As for QF1, there were many other problems that led to that little overland excursion other than merely the use of reverse thrust or not. To that airlines credit they learned very quickly. ."

Correct. Management complicating things. Trying to save fuel etc., by not using full reverse, on a runway with poor braking. Asking for trouble. Look for trouble and you will find it.

K.I.S!!

Last edited by doubleu-anker; 6th Jul 2012 at 11:47.
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Old 6th Jul 2012, 11:56
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Double A, i agree with you at 100%..,some people thinks they can re-invente hot water everyday..
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