Question for the "Airliner" Pilots

[magyar]

In flight school as you may know we learn how tro do a run-up and basically are taught to do it before every depature. As I progressed to work in the industry i leraned that with the smaller planes companies will have you do the run-up one a day or just before the first flight of the day and than thats it no more run-ups for the day unless somthing is fishy. So I arrive now at my main question, When i stand in the terminal building at say pearson airport and am getting ready to hop on my flight in say a 777 or something huge like that I come to wonder, when and how often is the run-up done on these planes?

[E-Flyer]

I thought the Run Up for most of the jet's was a Full Power Take Off on the first flight of the day? I am a bit hazy on where I heard or read that, not sure if that's true though.

[Airbrake]

never unless maintenance requires it.

[ScudRunner]

Simple Answer Never.

Aircraft like that will let you know if something isn't working right, Maintenance will take a jet to a specific spot on the airfield to perform a run up after a engine swap or maintenance. And no you wouldn't do a full power take off on the first flight of the day unless Weight/Runway/Conditions warrant it.

[AuxBatOn]

The way a prop airplane, piston or turbine, and a jet work is very different. On a piston prop, you'll need to maybe warm it up, make sure the carb heat works and the mags work. If you have constant speed props, you make sure the governer works. On a turbine prop, you make sure the governer and the autofeather works. On a jet engine, there is no such systems (they are associated to a piston engine or a prop). We rarely do run ups, only if on start, we do not meet certain criteria on the engine (ie: it idles lower or higher than expected). Sometimes, in the winter, we'll do run ups after landing to clear up the carbon on the fuel injectors. Otherwise, no run ups, balls to the walls and off we go.

[freakonature]

O.K. I'll bite. Is a one a day run up normal? Or fishy?

[Colibri]

When I started my private I was taught to do a run up every flight... even if the plane had been flying all day long. But then halfway through my instructor got a charter job and my new instructor was a retired airline guy. We only did run ups if it was the first flight of the day for the aircraft.

Same thing with my CPL and Multi instructors... each of these guys all had "real world" flying experience (one was ex-military and the other flew for Borek) and said if the planes been flying all you need to do is check the mags and do a governer check. It seems that most instructors or newbie instructors teach run ups for every flight. Maybe it's for that extra 0.1 or 0.2 on the hobbs... who knows.

[freakonature]

Thank's Colibri, that make's sense. But it's up to the pilot if they run up or not? No company would have it as SOP?

[Meatservo]

It would be in the SOPs. There's no need to repeat anything that AuxBatOn said. But I will anyway because I like to talk too much.

Piston: Warm up, check mags/carb heat/governor, first flight of the day, maybe again with new crew or if the plane sat and cooled off for a long time, or after maintenance.

Turbine(propeller): Check governor, autofeather, maybe run up to get bleed air to test de-ice boots, first flight of the day, maybe again with a new crew, or after maintenance.

Turbine(jet): No mags, no prop gov., no carb heat, no autofeather, usually no boots, therefore no run-up.

Turbines (prop or jet) sometimes need to be run-up to check rigging but engineers usually do this.

Look at it this way, if you already flew today then you've just for all intents and purposes done a really long run-up, so if something was busted you'd already know about it, wouldn't you?

Aero engines don't particularly like run-ups, the engine is not meant to run at high power settings without airflow, and it increases the chance of damage through picking up dust and ice and rocks and grass and whatever else is lying around. Plus, if you fly a big aeroplane you'll probably be asked to explain yourself for wasting fuel and time doing unnecessary run-ups.

Of course, the pilot-in-command can do a run-up any time he likes if he really feels it's necessary, like if the engine readings are ambiguous in some way, or you know something's a bit wrong and you'd like to get some instrument readings so you can tell the crew chief something more intelligent than "It's making a funny sound."

In conclusion, one run up per duty day, on a big jet, probably never.

[BoostedNihilist]

http://en.wikipedia.org/wiki/Carburetor_icing

all the reason I need to follow the runup related checklist... which includes carb heat - on

not that it has anything to do with an airliner but hey..

[skycoupe]

We do 60% run ups if we are taxiing in freezing precip or ground contam, once every 30 minutes and when in position for t/o

[Smitty]

As a student learning how to fly, you are doing a run-up mostly to get familiar on how to do one. So one every flight is common.

[Sulako]

If a jet engine works at all, it's likely going to work at a higher power setting. Runups aren't very useful in a jet from a pilot's perspective, they will just confirm what you already know - either the engine is turning or it isn't.

[stuckmike]

Not to mention all the x-mas bonuses getting blown out the tailpipe of all those 732's..........

[Vandriver]

As a student learning how to fly, you are doing a run-up mostly to get familiar on how to do one. So one every flight is common.

I concur, with ab initio students its mostly a familiarity exercise, also When instructing i'd usually take the opportunity to give a little tid-bit of information about one of the systems your testing. (ie. notice how the rpm rises a little before dropping off when leaning the mixture. why might that be....) In winter, depending on temperature a run-up might be required anyway.

[200hr Wonder]

Also remember that you are flying with people of all difference complacency in the same aircraft. Personally I run an flying school aircraft the first time I fly it for the day. Often times I have a bad mag or had to burn some crud out ot he cylinders because the pilot before was a bone head and did not lean for taxi and gummed everything up with lead or has no idea what a bad mag feels like. That said you can forgo the run up after you have done on on the plane on the day, just don't trust the guy before you and when in doubt try it out before you are air borne.

[Chuck Ellsworth]

Why do you do a run up?

[200hr Wonder]

Last I checked it was to ensure that the aircraft systems where operating within acceptable limits to be considered airworthy. Essentially I am trying to answer the question, do I trust this aircraft with my life?

[Chuck Ellsworth]

What systems?

[200hr Wonder]

In a bug smasher? Engine, Electrical, Vacuum, any system the requires the engine to be run at more than idle I suppose. Had not really thought of it.