Mysterious flap doesn’t come up problem - (solved)

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Christine
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Mysterious flap doesn’t come up problem - (solved)

Post by Christine »

I am planning on having my annual in 2 months early because of this problem, but maybe anyone of you has experienced this problem before, if so please share.
My flap ratchet - and I think the bushing too - is a bit worn (lever play) and will be replaced at my annual, but I can’t imagine that this causes my problem:
After take off with Flaps 1 notch (24deg), they won’t come back up airborne: I release the flap lever as usual and the lever comes down only half ways. The flaps may or may not come up a bit - I actually haven’t looked out while moving the lever only afterwards. As the ratchet is worn, they are anyways not in the full 24 degree down position it seems (with the flap lever at the one notch down position). The ratchet teeth are just a bit wide but otherwise prominent as they supposed to be.
On the ground I can put the flap lever in flaps up positions without any resistance. Flap in 40 degree work fine as does going back to 24. I flew one test pattern taking off with no flaps, pulling one notch in base and putting it back to flaps up position during that flight with no problem. Then I took off again with 1 notch of flaps, and the same thing, it would not get back into zero flap until touch down. The flap lever comes out of the 24degree position and I can push it about half ways down. But not all the way and the flaps may not even move. I took the right seat out and the channel cover and do not find any obstruction.
Previously I had two 1/4in cracks at the trailing edge of my flap and had the flap rebuilt with new skin. After reinstalling the flap, I had 3 take offs with no flap up problem and then I started getting the above indication.
If anyone had this or has an idea what this could be, I would be happy to read your input. Otherwise I have to wait to solve this mystery during my annual.

Happy Easter......
Last edited by Christine on Sun Apr 19, 2020 10:20 pm, edited 1 time in total.
Christine
06WN '88 MX7-180 MaulePilots.org Founder
ck "at" maulepilots "dot" org

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gdflys
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Post by gdflys »

Do you have the gust locks or the flap travel limit cables? I'd check the gust locks if installed to see if they're bent as well as the wing skins where the flap push rod goes through to make sure neither are binding. Check the full run of the flap cables to see if turnbuckles or anything else is catching anywhere.
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DeltaRomeo
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Post by DeltaRomeo »

Christine's Maule has the newer torque tube actuator for the flaps so the old M5 experience doesn't apply here. I have not seen how the newer system operates so I 'm not much help either.
M5

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Andy Young
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Post by Andy Young »

Hi Christine,

I don’t know what the problem is off the top of my head, but as do have some thoughts. It sounds like it is somehow related to air loads. Have you taken a good look at the newly-skinned flap to see if there are any wear indications from it binding on the surrounding wing or wing root fairing parts? It’s possible that the skin is just a bit oversized somewhere, and binds once the air pressure shifts it slightly.

Also, try opening up the zippers in the headliner and have a good look around at the mechanism while someone else operates it. Same with removing the rear bulkhead and looking at the cable and pulleys there. Maybe something has shifted or fallen into the mechanism somewhere.

Lastly, in the process of working on the flaps, did someone possibly remove the saddles that hold the torque tube out in the wing, and misalign them putting them back on? On some airplanes, I have found that they are not symmetrical, so if not mated correctly (as originally oriented) will bind.

My bet is on the repaired flap itself binding somewhere, or the torque tube saddle.

Do let us know what you find.

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Christine
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Post by Christine »

Thanks for your input.. I thought I had looked at everything, but then Jeremy asked me to look again .... then I found it. Yes, Andy, the gap between flap and trailing edge of the wing was a bit smaller towards the fuselage end and showed a bit of wear, but the culprit was a pop rivet right at the end which had failed and came up in an angle high enough to wedge over the trailing edge of the wing and jam the flap in the up movement..... An easy fix and now not that mysterious anymore.
Stay healthy and happy flying to everyone
Christine
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Andy Young
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Post by Andy Young »

Isn’t it SO satisfying when you have a problem, to find the smoking gun? Or I guess in this case the smoking rivet. ;-)

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