The Cessna 120-140 Association Forum

Has anyone wished they had a little more 'up' trim when landing? When I got my bird I noted the previous owner had something more than the 33 degrees required. I flew it like that for years until I thought I ought to get it back to spec. Now having thought about it and having to hold some back pressure I wondered if anyone ever had a similar sense. I carry a 16# tool/stuff collection in the baggage compartment and am solo.

(runway is closed here, I'm bored...!)
EMPTY WEIGHT 998.3 LBS.
EMPTY WEIGHT C.G. 13.29 (less fuel, includes oil) Empty Weight C. G. Range + 12.3 to +14.7
USEFUL LOAD 451.7 LBS.
GROSS WEIGHT 1450 LBS.

Hmmmm, I have factory settings and seem to have plenty of trim authority. Something else perhaps? (then again I have a 120 and no flaps.........)

Is the elevator in the neutral position (fared with the stabilizer)? When you run the trim back until the tab is evenly fared with the elevator, does the gauge say zero?

the elevator in the neutral position (fared with the stabilizer)? When you run the trim back until the tab is evenly fared with the elevator, does the gauge say zero?

Yup, I put everything in line and zero the digital gauge, then run the trim all the way up. Works the other way too. You can just barely see in the pic that the elevator is in line with the stab. I use the gauge to double check my mag timing also by mounting on the prop a certain way, works great.

Did you adjust it?
It looks like it is to specs.
Have you flown another 140 to compare it to?
If so did you compare the trim settings?

Rick

Never have felt the need, but I do tend to mostly wheel land, tail low. For reference, the trim used ranges from just around neutral on landing to about 1/4" forward of neutral for take off and cruise.

I'm hesitant to dial in too much up trim on landing in case GA is needed. TCDS is +6 / -33 degrees, so your inclinometer is about right. Pic appears to show max nose down trim tab setting.

Pic appears to show max nose down trim tab setting.

No, actually when the tab is 'down' on the elevator that is for 'up trim' or however we call it.

I'm a wheel lander so flaps are rarely at full for me, am aware of the nose down pitch with flaps.

I am reviewing my W&B work, maybe someone can find an error that my IA and I missed. It's a longshot. All empty weight plus oil. Here are the basics...

2004 W&B Since then the 'paper' W&B is as follows....
Remove Gill35 battery -27# at 56
Add Odyssey battery +15.4# at 56
Remove pull starter -16# at -25
Add Skytec starter +9.2# at -25
Remove seats and back -33# at 19.5
Add new upholstered seats ala' Lorraine Morris +15# at 19.5

Based on the data provided, and very quick math that should be checked of course, your moment decreased by about 830 "-lb, and your new empty weight c.g. would be about 12.9" at an empty weight of about 994#.

Have your A&P check these values and update your W&B.

The empty weight forward limit on a 120/140 is 12.3". Flying limit is 13.5" forward c.g.- pilot and fuel are positive moments that should bring your c.g. back into the flight approved c.g. Very roughly, a 185# pilot and full fuel should bring your flying c.g. back to about 15.7".

My aircraft empty weight c.g is about 14.1" for comparison. The same load as above brings my c.g. to about 16.1".Doesn't hurt to have to your A&P re-weight the aircraft. I kept my heavy battery as opposed to having a light weight one as these aircraft are more nose tippy than others I've flown (170, 180, Cub, etc.).