Throttle friction loose? Whats that all about?

[18greens]

Following on from Brakes Off, why do we set the thottle friction loose after we land? I can understand why you would want to set it tight before take off to stop the levers retreating on their own but whats the problem with leaving it there?

[BEagle]

Ever tried driving a car with a stiff accelerator linkage in a confined space?

It's to make your throttle movements easier.

[18greens]

Thanks Beagle,

Good point , makes sense.

[jarjam]

There is a problem with setting the friction nut too loose especialy on cessna's.
As you taxi in the vibration slowly increases the power setting and if the student dosn't guard the throttle you end up doing 25 kts on the taxi way.
as a rule I tell my students to disregard that check as the throttle friction should not be so tight in the first place that you cannot change power accurately.

JarJam

[pulse1]

I would be very interested to hear what people consider to be best practice with respect to throttle friction during final approach.

On Cessnas I find that a finely adjusted trickle of power during the flair helps a lot (better elevator authority). Too much throttle friction makes that difficult. Too little could mean that a sudden burst of power required to overcome wind shear could be excessive, or sudden turbulence could result in involuntary movement of the throttle.

My final check before landing therefore includes carb heat to cold, throttle friction off "a bit", after which I should not need to take my hand off the throttle again.

[Field In Sight]

When I first move the throttle when I get into a different aircraft I think to myself either

1. Oooohh that's a bit loose. Then tighten it up a bit.
2. Oooohh that's a bit tight. Then loosen it up a bit.
3. Oooohh that feels just about right. No tightening required.

It only needs to be tight enough to stop it vibrating into a different position and loose enough to move with a normal amount of force. One setting will suffice for both.

I don't have a typical training aircraft POH with me to check, but I suspect it is not part of the normal procedures checklist.

My personal opinion is the throttle friction check is superfluous and invented by the checklist manufacturers of the world.:p

FIS

[BEagle]

Really it only needs to be fairly tight for take-off, in case you should need to take your hand off the throttle at a crtitical stage of flight - then the throttle won't back off from the full power setting.

Land the aeroplane as the POH states. For a normal landing there shouldn't be any need to'add a trickle of power during the flare'.

'Short field' landings may, however, need a slightly different technique.

[BigEndBob]

On Cessnas, loosen the friction when you need to adjust then lock it with a twist of the wrist. So for taxi loosen, when you hold tighten, for takeoff loosen then twist tight for full power. On approach loosen, it won't drift much if you take your hand off to lower flap or trim.

Most Pipers usually find the little fibre washer has worn out (must only last 5 years!) so friction of cables usually enough to give sufficient friction (either that or the cables are dry and stiff).

I would would like to know on the 'after land checklist' what the panic is to switch the radios off other than txponder.
They were on for several minutes before dep. so three or four minutes after landing won't make much difference.

[Big Pistons Forever]

Field in Sight,

I am with you:ok: If the throttle tension is set corrctly before you start the engine it will be fine for the rest of the flight. If it isn't adjust it ! Checklists should be appropriate to the aircraft type and type of operation. The rest is why you teach good airmanship.

BTW my pet peeve with respect to checklist use in the PPL/CPL training environment is the runup mixture check, which seems to almost universally consist of " yank the knob out, engine dies, ram the knob in- check complete":* . What are other instructors pet peeves ?

[martinidoc]

One cautionary note about the throttle friction on PA28s. If the nut is tightened too much, I have noticed that on some aircraft, the mixture can move with the throttle, clearly an undesirable state of affairs.

[Obs cop]

Field in Sight,

I am with you on this one. I have yet to adjust the throttle friction in flight in the cessna I fly. I invariably set it to my preferred level prior to take off and leave well alone until after I have landed. I don't find the throttle moves or is unduely stiff during any of the demands I make of it. IMHO.

Obs cop

[skyfarmer]

Flying mainly Pipers, I have always thought playing with the throttle friction was a bit pointless, set it so it moves smoothly, if it does not, try and get it fixed!!!! Yea ok sometimes not possible.

Big Pistons Forever with regard to other pet peeves.. Cold morning, first run up of the day, engine cold, and the total insistance of sticking the nose right into wind. It is not as if the thing is going to overheat ...it needs warming up, if you are hot and high ( Joburg on a summers day!!) but in the uk in winter!!

Oh and number 2....The use of a checklist as a ToDo list, with no idea why each check is being done. Example:

Me: Why do we change fuel tanks before power checks
Student: Because the list says to do it.

Nothing about making sure there is fuel coming from that tank, fuel lines clear of contaminantes etc etc

[Big Pistons Forever]

Sky farmer

I sure have to agree with your second point. My experience is if the checklist said " scratch your bum " there would be a lot of ugly scenes in the cockpit:yuk: :rolleyes:

[Oktas8]

I was initially taught at a school which used checklists as if they were do-lists.

The best piece of advice my instructor gave me?
"Learn to start an engine without the checklist, because you look like a real plonker if you can't."

And from there I stopped and thought, and realised that piston checklists (for start, run-up etc) are a) not complicated and b) very similar across the piston fleet.

cheers,
O8

[skyfarmer]

It was about 8 years ago, with new PPl and abour 80 hrs when I did a bit of flying out of Adrmore (Flightline) in NZ when this was pointed out to me. They seemed a bit suprised that with a PPL and 80 hrs, I needed a checklist to start the thing. The same view seemed to prevail in South Africa



Is UK alone in this 'Must be done in the exact order according to the checklist' mentality ? This especially comes to light as often each club has slightly different checklists to other clubs, for the same aircraft type.