Runup after taxi back

luvflyin

luvflyin

Touchdown! Greaser!
Joined
May 8, 2015
Messages
17,444
Location
Santa Barbara, CA
Display Name
Luvflyin
Home Airfield
KVUO
I do a mag check after a full stop and taxiing back for a takeoff. Making sure a plug didn't get fouled on the way back. Wondering if thats common and if any other checks seem like good idea?
 
luvflyin said:
I do a mag check after a full stop and taxiing back for a takeoff. Making sure a plug didn't get fouled on the way back. Wondering if thats common and if any other checks seem like good idea?
Click to expand...
The first time I did a taxi back I asked the instructor about procedure. He said CIGAR, controls, instruments, gas, attitude (trim), radio. YMWV.
 
No engine stop, no runup.

Do you do runups on touch and goes, stop and goes, power changes in flight? Maybe no.
 
Unless that taxi-back requires me to hold for arriving traffic for a length of time, than I don't bother doing another mag check. It's unlikely that a plug would foul during a short taxi, especially if you aggressively lean as Bill says.
 
If the tower lets you do it then do whatever you want. If you are on a non-towered and do something like that then you will become the airport pariah.
 
Fouling shouldn't be an issue, but carb ice might be if you have a long wait. BTDT. Having a carb eat a hunk of ice at 200 AGL is not a pleasant feeling.
 
I don't normally do a check after landing, unless the plane has been siting long enough for the engine to get cold.
But, there is always the exception, even for me.
About 3 weeks ago I had just landed, and after taxiing back, I was pulling onto the runway at a towered airport and the engine stumbled, badly.
I lined up, then did a panel check, then started a mag check.
The tower asked what I was doing and I replied:
"Executing my responsibilities as Pilot In Command."
After I was finished, I told them what and why, and told them I was good to go. They cleared me and I went.
I suspect carb ice was the culprit.

For every reason you can come up with for getting the plane off the runway, I can give you a good reason for sitting still and doing the checks.
 
At high airports you need to lean it, so you need to do a runup.
 
For me I go with the old school "daily flight check" on my plane, between a good engine monitor and common sense you probably only need one at the start of the flight.
 
citizen5000 said:
If the tower lets you do it then do whatever you want. If you are on a non-towered and do something like that then you will become the airport pariah.
Click to expand...
If you're pausing on a taxiway, or otherwise gonna be in the way, sure thing, let tower know what you're doing, or plan on doing - maybe they'll direct you elsewhere, and it'll work out best for everyone. But if you feel a run-up is necessary for some reason, you aren't asking permission - you're informing tower what you've decided. There ain't no "let you do it" about it.

It's your call, not tower's, and it isn't on them to figure out if you have a rough runner, etc. I'd feel like an idiot saying "yeah, it was running rough, but tower wouldn't let me do a run-up!"
 
coloradobluesky said:
At high airports you need to lean it, so you need to do a runup.
Click to expand...

If he's doing a taxi back I would suspect he's just remaining the the pattern. In that case the mixture would still be set from the last takeoff (I haven't heard of anybody adjusting mixture on pattern work). No reason to touch the mixture.


Sent from my iPhone using Tapatalk
 
Sundancer said:
There ain't no "let you do it" about it.
Click to expand...

If you are on a runway doing a taxi-back you have been instructed and given permission to do that from ATC. If you then pause and try to do a mag check while still on the runway the tower will jump you because you did not have permission to do it. The same is true in non-towered. If you block the runway you become the problem.

The taxiway is less dangerous but still under control of ATC. Taxi permission comes from ground control. If you stop in a taxiway to do a mag check and block it ground control will admonish you.
 
A fresh runup is always prudent if you are doing a short field take off. Otherwise, you are wasting gas.
 
An open question, has anyone ever identified a fouled plug or an ungrounded mag on a back taxi mag check?

In my opinion I think it is a bad idea to do a “run-up” test between each back taxi for the following reasons:

When you do a run-up after each back taxi, You are stressing the engine in a high power, low airflow state that could end up in an unexpected engine or other part failure due to the added heat stress. Remember, your engine, your oil, and all the other parts inside the cowling is usually much hotter after you been flying the pattern than on your first run-up of the day, especially if It is a hot day and you are doing 5-6 take offs and landings with a back taxi and “run-up” with a Mag check on each one.

Second, when you are checking your Mags, you are now running all your cylinders with 1/2 of spark plugs not working (one spark plug in each cylinder not firing). If one spark plug was almost fouled before you started the check, it might now be fouled after the check, and you would not catch it. If you did this 5-6 times in a row, you could see how this might be a problem.

Third,
Each time you check the Mag. You increase the chance (even slightly) that you might forget to put it on both Mags before take-off

The time to check Mags after a back taxi is if on the full power takeoff run, the engine is not running correctly, abort the take-off! and then check the Mags and everything else (carb ice, water in tanks, timing, fouled plugs, etc).

Moreover, I think that you would be more likely identify a fouled plug during the flight around the pattern, thus you do not need to do a back taxi Mag check.
 
citizen5000 said:
If you are on a runway doing a taxi-back you have been instructed and given permission to do that from ATC. If you then pause and try to do a mag check while still on the runway the tower will jump you because you did not have permission to do it. The same is true in non-towered. If you block the runway you become the problem.

The taxiway is less dangerous but still under control of ATC. Taxi permission comes from ground control. If you stop in a taxiway to do a mag check and block it ground control will admonish you.
Click to expand...
Read first. Completley. Then comment.
 
luvflyin said:
I do a mag check after a full stop and taxiing back for a takeoff
Click to expand...

I don't land and do a full stop then taxi back and takeoff. If I did I would do a run up and check everything as per the takeoff check list.

It's not the fact that the plane has been running fine for an hour or two, it's the point that regardless of the time in the air there is a takeoff check list to follow. Quick mag check 15 seconds.....

Before I leave my tie down I lean and do a low power mag check just for the hell of it, works for me...:)
 
No mag check on a full-stop, taxi-back for me, but as others have mentioned, I aggressively lean on the ground, always.
 
Sundancer said:
Read first. Completley. Then comment.
Click to expand...
It appears that some posters may be missing the distinction between "back taxiing" and "taxiing back." To me back taxiing means remaining on the runway and proceeding against traffic to get to an exit or return to the beginning of the runway, while taxiing back means exiting the runway and taxiing back to the start for another takeoff. But it looks like some read the question as being about doing a run-up doing a back taxi, i.e., on the runway.
 
Last edited:
You must log in or register to reply here.
Back
Top