Piston Idle Speed

[Colonel Sanders]

I don't know what it is with AME's setting the idle
speed too high on both carbureted and fuel injected
piston/prop engines.

I flew two different (to me) aircraft today, and both
of them had the idle set at nearly 1000 RPM.

Please stop doing that. I don't know why you insist
on doing it, but please don't. It really screws up the
landings.

[iflyforpie]

It could have been set when the engine was cold (or not warm enough). I usually fly the aircraft, then set the idle speed.

Idle mixture set when it is cold will do the same thing.

I've also seen minor intake leaks (intake hoses, gaskets) pop up and raise the idle speed just enough to be noticeable.

But usually I am anal about keeping it as low as possible. On float planes you want them to be just ticking over in the 3-400 RPM range to help with sailing and docking. Usually I aim for about 500-600 RPM on land bound aircraft depending on what the Service Manual says.

[Colonel Sanders]

I would love 650 RPM. It's amazing how much a difference
even a couple hundred RPM makes to the landing distance.

950 RPM simply isn't acceptable as an idle speed and weirdly
enough, that's what both aircraft I flew today had set.

[Troubleshot]

http://www.youtube.com/watch?v=Ewq9NncD ... re=related

[Colonel Sanders]

Sure, but after you calm down, can you please stop
setting the idle speed so high?!

[flatface]

Deleted

[Colonel Sanders]

Would it piss the AME's off less if I pull the cowls and
adjust the idle speed/mixture myself? I really don't
mind getting my hands dirty - I have grease under my
fingernails and stained into the skin of my fingers and
thumbs.

I never ask anyone to do anything I wouldn't do.

[flatface]

Deleted

[Cat Driver]

Team work means everyone is on the team, and we all agree to the same rules to play the game.

Conversely the team can be controlled by morons.

So we should examine the team and if we come to the conclusion what the " team " is doing makes no sense then we should find another team to join.

Aviation is not a fuc.in " game " setting the idle to high on a simple basic training airplane is just plain stupid in my opinion.

So I personally would not support that team.

[GyvAir]

Odd thread. In my experience the conversation has always been something to the effect of:

Pilot/owner: "The idle seems to be set too high/low. Could you adjust that for me?"

AME: "Sure, no problem. What speed would you like it set to?"
(Obviously, with a mind to reasonable limits and AMM specifications, but I don't ever recall being asked for an unreasonable setting)

[torquey401]

If the idle isn't right, write it up in the logbook. Verbal snags mean nothing, right alongside post-it snags.

[ChallengerDan]

I am surprised that it took that long for somebody to suggest to write it up. I was thought that this is what logbooks are for, amongst other things.

[GyvAir]

Yes, write it up.
Have the conversation with the person maintaining your airplane too though.

[Spinner]

so perhaps we should disregard what the manual says for our engines?

ENGINE IO-240-A, B
Prop. RPM 1000

[Troubleshot]

so perhaps we should disregard what the manual says for our engines?

ENGINE IO-240-A, B
Prop. RPM 1000

Finally!...Thank-you....was waiting for that...

Instead of coming to maintenance forum and spouting off, how about you provide some more information. Did the AME in question set your idle speed wrong? or did he do what the manual said?

No matter how much you bitch and whine, a good AME will do what the manual says. Anyway I sense a "holier than thou" attitude here so I will not waste my time. I've seen RPM speeds in manuals in many ranges, but hey if you are having trouble with that..... maybe the idle speed is not the problem if you can read between the lines.

This is right up there with "hey my throttles are stiff" ...yeah turn friction knob CCW

[Colonel Sanders]

Did the AME in question set your idle speed wrong?

Sure did. Lyc O-320 E2D and TCM IO-360 are not supposed to
idle at 1000 RPM. Not sure if you guys care or not, but disregarding
the manual values makes the aircraft harder to land, and increases
the landing roll.

I don't think it's funny, me having to pull the cowls to set the idle
properly after you guys work on them, but I guess you disagree.

This has been going on for frikken decades.

[Spinner]

perhaps you should refer your guys to the TCM SB 97-3E which lays out most of the
idle speeds, fuel pressures etc for the TCM motors. The colonel is correct with regards to
the 360 engine, most idle speeds are either 600 or 700 depending on model.

link

http://www.tcmlink.com/pdf2/SID97-3E.pdf

for decades I have had pilots grab the aircraft and go running off without making a complaint until the
next inspection. If you have a problem then take it up with the mechanic right away. I have no doubt that
you can adjust the idle speeds on a carbed engine, anyone who has worked on a car can figure that out. But sometimes your fuel setups change with adjustments. And if you can't work it out perhaps it is time to get a new mechanic.

[Colonel Sanders]

Forty years ago, I remember that every time my father
and I got our airplane (TCM IO-360) back from annual,
it was a ritual that we had to pull the top cowl and set
the idle speed properly.

Forty years later, nothing has changed. AME's are still
setting the idle ridiculously high, and it's making it hard
for the student pilots to land, and it's unnecessarily
extending their landing distances as they float and float
in ground effect with the high idle.

In turn, they lock the brakes up and flat spot the tires -
sometimes they are even successful in shearing the
valve stems off when the tire creeps on the rim - in a
futile attempt to stop the airplane at anywhere book
distances.

I'm getting a little tired of this idle speed nonsense,
frankly. I can tell that I am a Bad Person (tm) for
daring to mention it.

Keep on flat spotting those tires, boys!

[GyvAir]

sighhh… I think the gambit is up, boys.

The Colonel is onto our clever, continent-wide conspiracy to entertain ourselves, sell tires and keep pilot egos in check all in one fell swoop.
Alas, it was so perfect; a small turn of a screw, set the lawn chairs up out on the ramp and watch, beer in hand, the inevitable floating, bouncing, tire burning landings. Then just wait for the freshly humbled pilot to come in, mouth shut, wallet open, to take one or two more 6.00-6s we’ve ordered in ahead by the dozens. Supplied and installed of course, at a suitably inflated markup and shop rate.
Of course, newly doubting one’s personal skills, a pilot would never have the temerity to question the AME as to whether he/she got every setting perfectly tuned on an aircraft fresh out of maintenance. Our ruse should have gone on indefinitely.
I’m not sure what we’ll do, now that we’re going to have to abide by the approved manual settings. It was a good run. Decades and decades, as he said. But, the fun is over and the money train has left the station. I guess we’ll just have to get up and go get honest, responsible jobs or something.

[Colonel Sanders]

Whatever. I've been cleaning up after you for 40
years, I'll do it for another 30 (shrug).

Keep on flat spotting those tires!

[roscoe]

Going back through the mists of time to the carefree days before websites, blogs, f'ing cell phones etc, it was a point of pride and a feeling of accomplishment to set up the aircraft you were responsible for with the slowest reliable idle speed possible. It made for happy pilots, smooth docking, and a lot fewer dents and holes in the floats and hulls. It also made sailing backwards towards the reefs, rocks, etc a lot less nerve wracking, especially for the guy in the tower (me).
Is following the manuals and using common sense a lost art???
My $0.02 for now, soon to be my $0.05......

[hoptwoit]

Maybe we should link this to the "AME discouraged" thread.

I love aircraft, I hate aviation.

[hangarline]

[quote="GyvAir"]sighhh… I think the gambit is up, boys.

The Colonel is onto our clever, continent-wide conspiracy to entertain ourselves, sell tires and keep pilot egos in check all in one fell swoop.
Alas, it was so perfect; a small turn of a screw, set the lawn chairs up out on the ramp and watch, beer in hand, the inevitable floating, bouncing, tire burning landings. Then just wait for the freshly humbled pilot to come in, mouth shut, wallet open, to take one or two more 6.00-6s we’ve ordered in ahead by the dozens. Supplied and installed of course, at a suitably inflated markup and shop rate.
Of course, newly doubting one’s personal skills, a pilot would never have the temerity to question the AME as to whether he/she got every setting perfectly tuned on an aircraft fresh out of maintenance. Our ruse should have gone on indefinitely.
I’m not sure what we’ll do, now that we’re going to have to abide by the approved manual settings. It was a good run. Decades and decades, as he said. But, the fun is over and the money train has left the station. I guess we’ll just have to get up and go get honest, responsible jobs or something.
sighhh… I think the gambit is up, boys.

bwahaaaaaaaa...thanks GyvAir, that was funny!

[torquey401]

I flew two different (to me) aircraft today, and both
of them had the idle set at nearly 1000 RPM.

What specific model of aircraft? Carb or injected? What was the idle cut-off like?

[Colonel Sanders]

172M (Lyc O-320) and M4-210C (TCM IO-360). ICO was ok.

Made the student's lives difficult in both by prolonging the
flare to land. Totally different aircraft. Really weird.