Engines Run-up

Fri Aug 11, 2000 7:51 pm

I was just reading about engine run-ups restrictions at ORD.

What is exactly an engine run-up? what purpose, characteristics, procedures, frequence...?

Thank you

Posts: 196
Joined: Fri Jul 07, 2000 12:28 am

RE: Engines Run-up

Fri Aug 11, 2000 10:17 pm

Engine run-ups are simply, running an engine. Maintenance will perform engine run-ups after a engine part has been changed, to verify its operating properly, or to verify a pilot discrepancy. Most of the time, engine runs are done at idle power. Idle runs can be done at the gate. but if a engine needs to be run at take-off power, then the aircraft will need to taxied to a safe spot on the airport. (I believe a 757 needs almost 2000 ft of clearance behind the aircraft to run the engine at take-off power.) Some airports have a desigated area to perform high power engine run-ups. others will have you taxi to an inactive runway.
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Joined: Mon Jul 10, 2000 4:51 am

RE: Engines Run-up

Sat Aug 12, 2000 5:18 am

JT8 is right. Also, there are noise concerns. I run a/c at YVR, and we have to get permission first, where the airport authority tells us where we can do it, as well as the heading we must use to direct the noise away from the neighbours, so to speak. A"power run" takes two people of course, and involves running the engines at high power settings to test and adjust engine performance. The person in the captains seat is responsible for the running of the a/c, and the right seat guy handles the radios, and generally keeps an eye out for trouble so the first man can concentrate on his job. As for frequencies, the right seat monitors ground control, and the left seat has the company mtce frequency.
Posts: 549
Joined: Thu May 20, 1999 7:16 am

RE: Engines Run-up

Tue Aug 15, 2000 9:21 am

When a run up is done are the breaks put on?

RE: Engines Run-up

Tue Aug 15, 2000 9:35 am

After Engine Changes, Fuel control changes, Gearbox changes, some indicating systems maintenance after heavy maintenance 'C' checks etc... as required by the Maintenance Manuals or work cards.
For multi engine heavy aircraft we use what we call the blast fence for takeoff power runup. It's a large heavy duty deflector that directs the jet blast up. The noise is still a problem, that is why there are restrictions at some airports and with most maintenance being completed on overnights it is a restraint.
One procedures is to make sure the aircraft is heavy enough not to jump the chocks. example...757-200 RB211 engines 45,000 lbs of fuel onboard minimum for take of power.
On the aircraft carrier we used a High power chain to secure the aircraft nose gear tow link to the deck and pointed the exhaust over the side.

RE: Engines Run-up

Sat Aug 19, 2000 12:04 am

Our engine run practices in the USAF are almost identical. On heavies we can run at idle power on the parking spot. Must get clearance from MOCC (maintenance control) and may not be able to run after 10:00pm depending on local politicians. If we run at take-off power we take the jet to a blast fence as mentioned before. On fighters, we can run at idle-76% in the spot. If we run from 80% to full burner we either take it to the trim pad or the hush house if one is available. Both the house and the pad have tie downs for the tailhook so the jet does not jump chocks.
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Joined: Tue Aug 08, 2000 10:34 am

RE: Engines Run-up

Sat Aug 26, 2000 11:52 am

We've almost forgotten about engine run-ups now. When I was a lad I often sat on a little block wall at the old terminal in SAN and watched lots of engine run-ups. All pre-turbine airplanes had to run-up, and still do.

Turbines are ready now!

Posts: 2141
Joined: Tue May 18, 1999 8:02 am

RE: Engines Run-up

Sat Sep 02, 2000 11:38 pm

Engine run-ups were recently brought to mind when I flew on a DC-3 in Alaska. Before we took off, we sat just off the end of the runway and ran up both engines, one at a time, to full power, then back to idle. Then we proceeded to turn onto the runway for take-off. I remember doing this many years ago on DC-6, DC-7, Martin 4-0-4, and Convair 440 aircraft. Why was it necessary for piston aircraft to do this, while turboprop and jet aircraft do not?

Bob Bradley
Richmond, VA
Fly Eastern's Golden Falcon DC-7B
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: Engines Run-up

Sun Sep 03, 2000 4:28 am

The reson for the prop run up is that a 'Mag Drop' is being carried out.

Each engine has two seperate ignition systems, powered by its own magneteo. Both ign systs normally operate togther. Prior to T.O. each engine is run up to T.O. power and one ign system is switched off, a note made of the RPM, then the sys is switched back on again. The other sys is then switched off & back on. The noted RPMs are then compared with that of both sys's operating. If the RPM drop with one sys operating is outside a specific tolerance it means that system is faulty in some way and requires rectifying.

If I remember correctly when I flew Cessa 152's the mag drop had to be not more thasn 150 RPM.

A jet engine, as you will know, has self sustaining combustion once it is lit up so no similar chks are required before T.O.

RE: Engines Run-up

Sun Sep 03, 2000 5:26 am

To twa747100,
Yes, the brakes, hyd. pumps and beacon light all have to be on, and should be listed in the checklist.

Jet-tech...TWA LGA !
Posts: 1368
Joined: Sat Jul 24, 1999 6:10 pm

RE: Engines Run-up

Mon Sep 04, 2000 3:23 pm

When I was in IAH waiting for my flight to JAX, the plane I was to be flying on the pilot ran up the #2 engine on the 737, I know it was more than idle, They ran it up for about 3 minutes then just shut it down.

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