The International Cessna^® 170 Association

Well here ya go fellas, I've got a question.....

In my new (to me) 170B, I don't have enough nose down trim. This happens with me solo with nothing in the back, two 190 pounders in the front seats with nothing in the back, and solo with some gear (I didn't weight it) in the baggage compartment. Obviously, it is more of a problem with weight in the back, but I've noticed it on every flight.

I especially notice it while on approach with flaps extended. The flaps give a nose up pitching tendency, which I over come and then trim to fly hands off. Only I run the trim to the stop right away. For what it's worth, when at this forward "stop", the trim indicator is only about a quarter inch forward of the takeoff setting.

I just flew a bit this morning but didn't have time to troubleshoot after I returned. Thought I would ask here before I go back out to the airport this afternoon.

Is this normal?

Thanks,
Keith

Wow. Twice in one day, and it's not even noon yet.

I rec'd a wake up call this morning from another member who questioned his trim tab rigging. Here's the text from "Rigging the 170" by Tom Hall (edited by me.)

ELEVATOR TAB

(a) C-170 & C170A
1. The elevator tab is actuated by a cable which has a chain incorporated in each end. The chain in front is actuated by the fingertip tab control, and the one at the rear operates a screwjack, which mounted in the right half of the stabilizer. The travel is 10 degrees up and 27 degree down plus or minus 1 degree.
2. Turn the tab control wheel to the full forward position, and the screwjack to the full up position. Then turn the screwjack back ½ turn. Set the chain on spockets at each end, allowing ½” to 1” overlap in the direction of travel. Tighten the cable tension to approximately 30 lbs.
3. To set the tab travel the elevator must be in neutral position.
4. Turn tab control to full forward position, disconnect the push-pull tube from taband adjust it to hold the tab approximately 11 degrees. This can be done by screwing it in or out. Connect the push-pull tube to the tab and turn the tab control to the full rearward position. The tab should be approximately 28 degrees.
5. Set the stops between first and second bulkhead rear of the baggage compartment on the cables for correct travel, which is 10 degrees up and 27 degrees down.
(b) C- 170B
1. The elevator tab is actuated by a cable which has a chain attached to each end. The chain in front is actuated by the fingertip tab control, and the one at the rear operates the crew jack, which is mounted in the right half of the stabilizer. The travel is 12 degrees up and 25 degrees down, plus 1degree or minus 0 degree.
2. Turn tab control wheel to the full forward position and the screwjack to the full up position. Then turn the screwjack back ½ turn. Set the chain on the sprocket at each end, allowing ½” to 1” overlap at each end in direction of travel. Tighten the cable to approximately 30 lbs.
3. To set the tab travel the elevator must be in neutral position.
4. Turn the tab control to full-forward position, disconnect the push-pull tube from the tab and adjust to hold the tab at approximately 13 degrees. Reconnect the push-pull tube to the tab and turn the tab control to the full rearward position. The tab should be approximately 26 degrees.
5. Set stops between the first and second bulkhead rear of the baggage compartment on cables for correct travel, which is 12 degrees up and 25 degrees down.

AND ...YES.... The trim indicator will not travel fully forward within it's indicating slot when trimmed fully nose-down. This is normal.

What George should have said first is NO IT IS NOT NORMAL.

Hmmn. I think Bruce and I were posting simultaneously as I edited my closing remarks (which Bruce would not have seen just yet.)

The inability to obtain sufficient forward trim is not normal. The indicator indices giving an indication well aft of the forward-most position within that slot on the tunnel.... IS normal.

Check your rigging per the instructions.

Thanks guys. I didn't think it was normal to not have enough trim, especially when it happened with a relatively forward load.

I'll check it per the instructions. Sounds like my first project!

I'll keep you posted re: the result.
Keith

Keith-
If you don't get the problem solved, stop by Mountain Airframe in Mena on your road trip and let Del take a look at it. My 170 had a heavy wing problem and it didn't take Del long to figure out both wings were twisted wrong.

I'd agree with Bruce that you have an issue and as George suggests just hold the elevator neutral (faired to stab) and see how much the tab will rise above the elevator. Also check that the blocks (mid fuselage floor area) on the cables that limit travel have not been displaced or have something fouling them.

hilltop170 wrote:Keith-
If you don't get the problem solved, stop by Mountain Airframe in Mena on your road trip and let Del take a look at it. I had a heavy wing problem and it didn't take Del long to figure out both wings were twisted wrong.

It takes a twisted mechanic to notice a twisted wing And a set of wing twisters to fix em'.
Thanks Richard

That's a good idea Richard. Since my mechanic here in Georgia is a friend who will be working in exchange for cold beverages, I hate to impose on him too much. I'm going back to the airport this afternoon and will take a closer look at the trim system to see if the problem is something obvious.

Del, I may be making a trip through your part of the country in a month or so anyway. I'll call you in a couple of weeks to discuss a couple of things I might want you to look at for me. Looks like I need to start a list.......

Thanks,
Keith

Keith,
I would be happy to work on this for you, and you would not be imposing on me if you wanted to barter for cold beverages.

wingnut wrote:Keith,
I would be happy to work on this for you, and you would not be imposing on me if you wanted to barter for cold beverages.

Keith, I think (reading between the lines) that Del thinks he's gonna be OWED by YOU. (Seeing as how he CANNOT AFFORD TO LOSE in any barter deal! (There's no beer in Mena.)

gahorn wrote: (There's no beer in Mena.)

Yeah, we just found that out. The closest is 18 miles west in Oklahoma but it's still 3.2!

Keith- If you decide to barter, bring real beer and it will be worth a premium.