1951 C170A Flap Issue

[danparm]

A friend of mine was going to take my 170 flying this morning and discovered before the preflight that the right flap was partially down even though the flap handle was down and the left flap fully retracted. I'll let the video speak for itself: https://vimeo.com/140377045

When I had some time later I removed the inspection panels from both wings to see some of the flap rigging: https://www.flickr.com/gp/70875560@N08/BS1QFZ

Got a video of what is causing the bind on the right flap: https://vimeo.com/140376701

Notice that the pilot side doesn't have the culprit bracket? Is that bracket supposed to hold the flap in the event that the return spring fails?

So I guess I have two issues:
1) Bracket causing flap to bind
2) Missing bracket that could be a safety issue

Anyone experience anything similar or know for sure what that bracket is for?

[LBPilot82]

I had the same issue on my 170A. The problem is your gust lock is not latching correctly. If the the latch (at the end of the flap cable) is not able to grab the stationary bracket and the flap is manually lowered, it will get bound upon trying to return to the retracted position. If the flap handle is pulled slightly and then released the flap will return to fully retracted. I can't recall exactly how I fixed it but there was some adjustment to allow the gust lock to grab the bracket (I think the bracket is slotted). In your video, it looks like your gust lock hook needs to move slightly outboard from the wing root in order to grab the bracket. This design definitely leaves much to be desired. Hope this helps.

[Bruce Fenstermacher]

Richard described it pretty well. When the flap gets pushed down in this position lifting the flap handle a little will move the gust hook and release the flap back to normal position.

The function of that hook is to hold the flap in position in a gust on the ground. It has no other function. It does not work very well. It is very common for one to observe an A model with the flaps being blown about in a gust. Don't trust the gust locks, always use a gust lock between the fuselage and the flap while tied down and if sitting on the ramp in gusty winds pull the flaps to the first position which will lock them.

You say the other side doesn't have it? That's because it's broke or someone removed the locking tab.

Botton line. So there is nothing different about your 170A flap than every other 170A.

[Metal Master]

A friend of mine was going to take my 170 flying this morning and discovered before the preflight that the right flap was partially down even though the flap handle was down and the left flap fully retracted. I'll let the video speak for itself: https://vimeo.com/140377045

When I had some time later I removed the inspection panels from both wings to see some of the flap rigging: https://www.flickr.com/gp/70875560@N08/BS1QFZ

Got a video of what is causing the bind on the right flap: https://vimeo.com/140376701

Notice that the pilot side doesn't have the culprit bracket? Is that bracket supposed to hold the flap in the event that the return spring fails?

So I guess I have two issues:
1) Bracket causing flap to bind
2) Missing bracket that could be a safety issue

Anyone experience anything similar or know for sure what that bracket is for?

The flaps on the 170A are spring loaded up
They are pulled down with the flap cable which is connected from each flap to a central cable in the overhead. The central cable goes down to the flap handle at the center consul thru the pulley’s at the back of the cabin. The adjustment for each cable is in the overhead aft of the zipper in the cabin. Turn barrels for each flap.
Your flap actuation has several problems.
#1 issue: It is missing the flap latch bracket in the right wing root. However even if both latch brackets were missing the flaps would still actuate evenly to all positions with operation of the flap handle.
The J brackets have two functions. They act as a gust lock in the full up position. And they act as an up stop for full up position of the cable movement. Note: The full up position of the Flaps is stopped by the four adjustment bolts on the aft spar of the wing.
#2 issue. If the flaps are full up you should not be able to pull them down from outside of the airplane if the up latches are rigged properly. Can you pull the left Flap down when the flaps are full up? IF so then the left cable is rigged to tight. It should be rigged so that when the flap reaches the full up position that the latch engages and the flap is secured in the up position. The J hook can be slid forward and aft in slots in the bracket to help this latching.
#3 issue. It appears there is wear in your left flap bracketry that is causing lost motion. When you first start to operate the flaps from the full up position the cable should first pull the Latch hooks open or disengaged on both flaps at the wing root by the action of the linkages in the wing root area. And then start pulling the flaps down equally. Each flap is rigged independently.
#4 issue. I think the weird latching in the approximate 10 degree angle of the right flap is being caused by the right flap return spring catching on the cut out in the rear spar as evidenced by the snapping spring sound in the video that was posted.
Further note: If the flaps were both up and the latches in both wings were not latched. You would be able to pull either flap down against the spring to the full down position from either trailing edge. Put your flaps in the 20 degree position go outside and pull down on the flaps you will see what I mean. The Cable only pulls the flaps down not up. The only thing that happens is that the cable goes slack. If you do this don’t let go of the flap when pulling it down as it will snap back up because of the spring pulling it.
At least that is what I think?
Regards,
Jim

[danparm]

Thanks for the replies/info.

Very interesting that those parts are a gust lock. I carry aileron/flap locks for when it does stay outside, which is rare.

I'm wondering how it ended up in this partially down position. Before yesterday I had flown the plane on Sunday and never noticed the right flap being partially down when I pulled it back in the hangar.

The issue explains a mystery from a couple months ago. On a flight from OMH to CHO I noticed I was applying considerable left rudder to keep the plane coordinated in cruise. If I took my foot off the pedal the nose swung way to the right. I guess I'll be cycling the flaps before every take off now and verifying that both go completely up. I will also look into the rigging and make sure that is kosher.

Thanks again.

[Bruce Fenstermacher]

#2 issue. If the flaps are full up you should not be able to pull them down from outside of the airplane if the up latches are rigged properly.

And if the parts are new.

As most 170A parts are not new, you can easily pull done on most 170A flaps and they will be set in the exact position you show in the video.

[mongo2]

In the 170A IPC, Figure 17, item 21 shows the flap handle. It also shows 2 holes in the area where the cable attaches. I used the lower hole during pre-rigging, and even with the correct tension and travel, the cable is rubbing on the lower aft bulkhead hole where it first passes through, going aft...
Now it's looking like the upper hole would have been the correct choice.. it will move the cable up and aft about 1 inch, which will now require re-tensioning, after having already been saftied ... oh well.should have seen it earlier, and a closer look shows what was probably the original attach point by wear mark...there was no cable installed when i got the project......... My question is , why the 2 holes in the handle..?

RC