Rolling takeoff with a TFE-731

[Capt1124]

I have seen the Honeywell video in which the company adamantly states you must not do a rolling takeoff with this engine. The Westwind AFM doesn't say this. I would be willing to go along with this, however 1) static takeoffs are not always a good idea, such as on a slick runway, and 2) we have a regulator approved manual that says rolling takeoffs are permissible with extra runway.

My preference would be to let sleeping dogs lie, but since Honeywell is so insistent about this, what are the opinions of those who have flown 731 equipped airplanes?

 

[hawkerjet]

One of the effects of a static takeoff at heavier weights is hotter brakes. I usually pause through 65 % release the brakes and set power. On days when I do the full static then I leave the gear down for an extra second or two before retracting, for cooling. ( Westwind A/C)

 

[Canucit]

where can I see the video from honeywell, and is that for all 731"s or just on the westwind
thanks

 

[Capt1124]

A guy I used to do training with has the video. The airplane used in it is a Citation III so I beieve it applies to all aircraft with 731s. They say unless takeoff N1 is observed before brake release, you make not get full power until a few hundred feet off the ground.

 

[ultrarunner]

Better to have a carbon seal blow out earlier than later. I do no miss that engine.

 

[Seadogrun]

I'm interested in seeing this video also. What was the contex of the statement? Is it a CYA runway performance statement?

Some airplanes(may not be 731) you may not use static power under certain X-wind values.

 

[con-pilot]

I don't believe I have ever seen that restriction on any of the 731 powered aircraft I have flown, the Sabre 65, Falcon 50/900, JetStar 731 nor the Westwind I/II.

I'm not saying there is no restriction, but sure don't remember any about not doing a rolling takeoff. God knows I have done enough of them with no problems.

Could this be something fairly new?

 

[NW Flyer]

It was never mentioned to me during training for the Lear 45, and I do remember a blurb about adding a percentage to the takeoff roll if you perform a rolling takeoff.

I do know that if you wait to see takeoff N1 before brake release in the 45, especially a lightly loaded one, you will scare your pax and dump the catering on the floor. Not recommended.

 

[Lead Sled]

The only thing I ever remember hearing from Honeywell, ne Allied Signal, ne Garrett was that takeoff distances began from whatever point you were at when the takeoff N1 was achieved - regardless of your ground speed. They also specificed that takeoff N1 was a minimum number. I have documentation on the latter, but not on the former. It was years ago though at some NBAA shindig.

LS

 

[avbug]

I don't believe the N1 values are minimums; those should represent max values for takeoff, and are temperature and altitude based. I'm looking at a LR35 QRH right now and it states the %N1 numbers are maximum values.

I suspect that what's implied by the inference that they're minimum numbers is the meaning that these values are the gauranteed thrust producers. The only real limitation is the temperature and the upper RPM values. Likewise, published distances won't be valid unless the proceedures published with them are used. A rolling takeoff can't predict where and how fast power application will occur, and accordingly, puts the takeoff numbers out the window.

N1 is an easy to use value, but it also doesn't really describe thrust. It's just a speed, and the condition of the engine and fan, as well as the ambient conditions, really dictate what thrust is being produced. That may be the reason for the data being describe the way you have it; that fan speed is a number that may represent the minimum value to produce rated thrust...though the truth is that the engine may not really be putting that out, anyway.

If I'm setting a preplanned N1 value, I'm of course watching the temps, and may limit the engine before that value is reached, or be tweaking the power back to respect the temps during the roll. It's the engine temp that's limiting, assuming the fuel computer does it's job. If the mechanical goernor/fuel computer is working properly, especially with DEECs, then temp shouldn't be an issue either...but I never make that assumption.

If runway isn't a big issue, then I much prefer to let the airplane roll. I don't like to do rolling takeoffs from the taxiway; I've seen a number of pilots apply power from the first point they start to enter the runway, and that turning moment is very tough on gear. I saw a tire get peeled off the wheel assy on a C-130 that way. I prefer to line up, do a final check, then power up and let it roll. I'll usually hold the brakes for partial power; I prefer to establish a stable power setting and do a crosscheck through all engines, and I think it makes for a smoother power application. It eliminates any low end surges or hesitations if all engines are partially and equally spooled before brake release.

Someone else mentioned not wanting to do full power braked releases. I don't know that excess brake energy is imparted if the wheel isn't in motion, but the lurch as the aircaft comes out of brake release isn't smooth, and it's not good for passengers.

So far as there being problems with the TFE-731...it's one of the best corporate engines out there. I don't know why anyone would be glad to be rid of them.