170B Throttle Position

[ToolHead]

My 55 170B throttle does not push all the way to the dash at idle. It feels awkward when I push in to idle and the knob stays out an inch from the dash. Sometimes I almost bend the dash in. Is this a normal throttle position on some 170s or has someone installed the wrong cable. Is the throttle cable adjustable so that the knob is pretty much at the dash when pushed all the way in to idle?

ToolHead
4424F

[T. C. Downey]

Sounds like it is installed wrong. I like a little cushion but not an inch.

[Bruce Fenstermacher]

Sounds like it is installed a lot wrong. Idle is throttle all the way out, not in.

Yes the throttle position relative to rpm can be adjusted within limits and how far you must move the throttle relative to rpm change can be adjusted within limits. How far the throttle starts from the instrument panel and where it stops before the instrument panel can be adjusted within limits.

You do not really want the throttle to be fully in when at full throttle. You want it to be just shy of all the way in. In other words the carb being in the full open position stops the throttle movement, not the instrument panel or cable limit. At idle you want the idle stop to be the limiting factor not the cable.

There are a few variables to adjusting the throttle cable to the carb. It is not complicated if you understand such things but can be if you don't understand and have some experience with the relationship of the cable to carb control arm, the relationship of the cable angle to the carb arm and so forth.

[canav8]

Toolhead, Is this some kind of joke? If your throttle is installed the way you say it is and you did not do the installation, I would stop flying that aircraft and have a qualified mechanic look over that entire aircraft. That is seriously wrong. Not sure what else could be wrong with the aircraft! I have seen guys do their own maintenance and get things screwed up but not a throttle. Did you think it was suspicious the first time you flew that aircraft? Im just asking. D

[170C]

Reminds me of a bad situation that occurred in Texas quite a number of years ago at a warbird restoration facility. A F-4U Corsair had been restored by the team and it was time to do a fresh overhauled engine start. The plane was pushed out of the hangar and chocked, facing the closed hangar door. Upon the engine being started the engine speed was too high and the person in the cockpit pulled the throttle back to lower the rpm. Problem was the throttle had been hooked up backward. With the throttle being pulled back the engine increased to full rpm. The plane jumped the chocks, ran into the hangar door, tore through it flinging door pieces all over the place and resulting in a worker losing a leg. Bad situation! Check that throttle out before operating your 170 again!

[blueldr]

Sounds to me like Toolhead is fooling arond with a pre-WWII French airplane. Their aircraft throttles operated in the reverse of ours.
Do you suppose he's just pulling our legs? No American pilot could possibly be that ignorant of throttle operation.

[ToolHead]

Thanks a ton and I apologize. I know all of you heard the loud pop just now as I pulled my head out. I had a very very senior moment typing in my description last night. It's when I push in full throttle on takeoff when I nearly push the throttle through the dash due to 1-the old sluggish Tach and 2-the one inch still remaining between the knob and the dash. I understand from you replies there is some adjustment, but it could be installed incorrectly as well. I'll fly it over to my A&P for repairs.

I apologize for the confusion I caused. Thanks for your help.

ToolHead

[Bruce Fenstermacher]

I don't think an inch from the instrument panel is overly excessive. You could probably pay your A&P his hourly rate for an hour or two to get it closer. I wouldn't do that till annual when it will have the cowl off and should be looked at anyway. I would do this adjustment myself and I wouldn't pull the cowl just for that so I sure wouldn't pay someone.

Is your throttle sticky or perhaps so loose you can't control how hard or fast you push it in? That would be a reason for some maintenance. Or if you suspect your are not getting full RPM because something is stopping your throttle short.

You say you try to push the throttle through the instrument panel. Why? I advance the throttle at a steady pace, not so fast as to cause the engine to stumble or I loose control from torque, and when it stops, it must be at the end of travel. I don't try to continue pushing it. You are probably exaggerating a bit, I get that. One thing I've always done when confronted with things such as your throttle position. When the throttle stops and it is full in, I stick my index finger out and measure that distance. An inch is about on joints width. Next time I would push the throttle till it stops then measure again so my mind is satisfied the throttle is fully in. No forcing necessary. I've used this technique on just about every airframe I've flown.

[ToolHead]

Bruce, thanks again for the advice. The throttle is not particularly sticky, maybe a tad over average. I'll try your finger joint tip and then have it looked at during the next annual.

Greatfull ToolHead

[KS170A]

The only "real" important thing here is that movement of the throttle control in the cockpit achieves full and proper range of travel on the carburetor control. As in, when the throttle stops at idle, the carburetor control is against the idle stop screw. When the throttle control is max forward, the carb control is against the other stop. Each and every thing the pilot controls (throttle, mixture, all flight controls) should reach the mechanical stop at the control (carb, flight control stop, etc) before the pilot end reaches the stop (throttle against the panel at full open). For example, you should be able to rotate the yoke each way until you feel a stop, and then if you keep applying pressure, you'll feel a second stop. The first should be the aileron bellcrank reaching the stop, followed by the yoke. By reaching the stop out at the control, the pilot knows there is nothing more available. I've flown some airplanes that had mis-rigged power levers where I ran out of throttle movement way before I reached torque or temperature limits (this was in a turbine airplane).

[Bruce Fenstermacher]

Another thing to keep in mind. I've noticed that Cessna did not overly build these instrument panels. I can recall seeing a 170 instrument panel that doesn't flex a bit when the throttle is moved. Most of my time is in 52 and earlier aircraft so this might be more particular to those years. I wouldn't be alarmed to see it in later years.

[minton]

My 55 170B throttle does not push all the way to the dash at idle. It feels awkward when I push in to idle and the knob stays out an inch from the dash. Sometimes I almost bend the dash in. Is this a normal throttle position on some 170s or has someone installed the wrong cable. Is the throttle cable adjustable so that the knob is pretty much at the dash when pushed all the way in to idle?

ToolHead
4424F

Tool Head,

This is SCARRIE!!!! How many annuals has this plane gone through?? PUSH, GO, PULL, STOP At least one inch gap at T/O power. Right up there with reverse rigged flight controls. Turn your mechanic in to the FAA!! AND don't fly the damn thing until it's gone through and passes a real annual.

Some people sugar coat things but cummon!!

[Bruce Fenstermacher]

Guys guys, read the whole thread. Toolhead made a mistake in writing, he said that. Give him a break. I'd pounce on him for it but I think I might have made the same mistake once.

[minton]

Sorry Still sounds as if he needs a good inspection and a good rigger to help him out

[Bruce Fenstermacher]

Sorry Still sounds as if he needs a good inspection and a good rigger to help him out

He very well may and isn't that what he asked in his first post.