M-5 flap uplock

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Dale Smith
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Re: M-5 flap uplock

Post by Dale Smith »

I think I can see in the picture that the extra bolt is holding a bracket that is larger that the original return spring bracket??? I took the up locks off of my M-5 a while back. I will take a look at the part I took off and see. I’m curious now.
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Dale Smith
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Re: M-5 flap uplock

Post by Dale Smith »

I was curious so I went and dug out the parts From my plane when I removed the up locks, I also replaced the bell cranks at the same time. I believe what I see in your picture is that some one made there own version of parts to remove the up locks. If you reference Drawing 2130E Rev A item #3 (Shackle Half) I think they reused that part and drilled a hole to mount it. If you were to look at it from the bottom I would bet it has a slotted hole in it. When you remove the up locks per Drawing 2003 Rev F sheet 2, that shackle half is replace with item #4 or 50 (cable Shackle) to mount the flap cable, and item #19 (shackle, AKA flat tab) to mount the return spring to.

Hope this Helps. If you need picture, I can try to get some.
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krautman67
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Re: M-5 flap uplock

Post by krautman67 »

Same issues with mine. 1976 M5. First flap issue I noticed was asymmetric flap deployment. Going from flaps up to flap 20, right flap would go to 4 or 5 degrees before the left flap started to move, resulting in a significant roll to the left. As In an earlier post from Jeremy, the right flap cable is adjustable, the left cable is fixed. This adjustment turnbuckle is in the headliner, after the split from the main cable from the handle behind the rear seat. I slacked the right flap to match the left, to establish synchronized flaps. I then measured / verified the flap angle at up, 20 and 40 degrees. I marked the spot in the back window where the trailing edge of the flaps were from a line of sight from the pilot seat in flight. Did a test flight, as flap 40 was selected I had a look, the flaps had blown back to close to the 20 degree mark at 80mph. (Thanks for the procedure Jeremy). I then adjusted the main flap pull cable turnbuckle behind the back seat to its shortest setting, and verified that the flap travel limit cable was set to 40 degrees. (This cable is on each inboard flap actuator rod) This effectively caused the flaps to reach 40 degrees well before reaching the 40 degree detent in the flap lever. I thought this extra cable tension would securely hold the flaps at 40 degrees under aerodynamic load. It did not, the flaps still blow back to about 30 degrees in flight. After reading your post, I will now investigate if the return spring bracket, or actuator is loose or a missing fastener where it attaches to the rear spar. Something is way out of tolerance here. I’ll let you know if I find the problem:). I see no uplock in mine either, I suspect it may have been removed when the flaps 20/40 mod was done.

CORRECTION: Mine has the flaps down limit cable, so therefor the uplock was removed, it's one system or the other.
.....Carl
Last edited by krautman67 on Mon Nov 02, 2020 7:29 am, edited 1 time in total.
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Re: M-5 flap uplock

Post by maules.com »

With gust lock removed, the flap cable goes direct to the bell crank via the link piece.
Try to move the bell crank up and down instead of its normal arced travel. If it moves up and down, one cannot achieve max flaps as the slop is not allowing full movement of flap lever and ratchet and dog to fully translate all that movement to the flaps.
The bell crank bushing wears, the pivot bolt wears, the pivot bolt holes in the bracket can become oval, the bracket can become misshaped or loose on its mount bolts. The flap hinge post bushing and special knurled pin can become worn.
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Re: M-5 flap uplock

Post by 7336C »

Dale Smith wrote:
Tue Oct 06, 2020 11:36 am
I was curious so I went and dug out the parts From my plane when I removed the up locks, I also replaced the bell cranks at the same time. I believe what I see in your picture is that some one made there own version of parts to remove the up locks. If you reference Drawing 2130E Rev A item #3 (Shackle Half) I think they reused that part and drilled a hole to mount it. If you were to look at it from the bottom I would bet it has a slotted hole in it. When you remove the up locks per Drawing 2003 Rev F sheet 2, that shackle half is replace with item #4 or 50 (cable Shackle) to mount the flap cable, and item #19 (shackle, AKA flat tab) to mount the return spring to.

Hope this Helps. If you need picture, I can try to get some.
Hi Dale,

Thanks for your reply. I agree, it looks like an unofficial modification of the flap locks to reuse some parts. Thanks for checking.
Zsolt
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krautman67
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Re: M-5 flap uplock

Post by krautman67 »

Thank You Jeremy!
I checked all the pulleys and attach points, but did not look that closely at the bellcrank. Looking at the photo from 7336C, it looks like that bellcrank will be accessible with the loss of some knuckle skin, blood, and swearing. The bracket attached to the rear spar that holds the bellcrank looks like it requires access to the forward side of the aft spar. If so, maybe it's time to pull a wing skin and do the upgross mod....
Carl
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AndrewK
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Re: M-5 flap uplock

Post by AndrewK »

Great thread. I've been meaning to go through my flaps and make sure I am getting the most out of them so I appreciate all the info.
I have the M5 gust locks, looks like the upper skin on one wing already has a patch where I assume one lock decided to pop through at some point in the past but currently they are straight and working.
However, in the interest of getting the most out of my flaps I reached out to Maule and ordered the "Flap limit cable kit". Not sure if it was a kit prior to my order but Kasey said it is offered as one now: $165

Earlier in the summer I measured my flap angles on the ground and they looked good, would need to dig through my notes for the exact angles. I used masking tape on the fuselage to mark their positions in respect to a GoPro on the wing tiedown ring and went flying to see how much deflection there is at different speeds. I used the 1st and 2nd notches at the higher speeds and gradually stepped down to the 3rd notch at the slower speeds.

I feel like the different is pretty significant so I will be going through the entire system to check and fix slack at all the points mentioned in previous posts. Has anyone done anything similar and care to comment on how my flaps compare to yours?

Ignore my hand gestures, I was signaling my notch count and speeds to the video camera.

Ground - 1st notch (used the tan masking tape, hard to see)
Image

80mph - 1st notch
Image

Ground - 2nd notch
Image

70mph - 2nd notch
Image

Ground - 3rd notch
Image

65mph - 3rd notch
Image

60mph - 3rd notch
Image

55mph - 3rd notch
Image

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krautman67
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Re: M-5 flap uplock

Post by krautman67 »

Hi Andrew,
Your investigation skills are top notch! I would say that after I adjusted all the pull cables, my flap blow-back in flight is VERY close to yours. Your back-seat AME also takes a keen interest in flap deployment angles....until the 4th or 5th frame :)
It looks like you do not have the flap 20/40 mod done, since this would only give you up + two notches. This does not have much significance in the problem we are discussing, but your photos indicate very clearly that under aerodynamic load your flap travel is about 8-10 degrees shy of the selected position. The published performance figures are therefore way out the window. If you are hot and heavy, you are basically taking off with flaps zero at the first notch, just as you achieve flying speed. This is a very large concern if you fly from a field length that requires "Maule Performance". I'm going flying on Wednesday, I will do a close inspection of the bellcrank as Jermey describes.
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Re: M-5 flap uplock

Post by maules.com »

With a length of 2x4 one can simulate the air load on the flap by deploying them and pushing back spreading the load with 2x4, then measure the angle relative to bottom of wing with a protractor or cardboard marked at the angles required.
You can access the bell crank bracket fasteners by raising the inboard fuel tank lid.
Jeremy
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JerseyJim
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Re: M-5 flap uplock

Post by JerseyJim »

AndrewK I believe someone put a M7 flap ratchet in your M5 or cut an additional notch in your M5 ratchet. M5 were 15-35deg on early and 20-40 on late models. Yours seems to have 3 down positions in addition to the zero or up position.
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krautman67
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Re: M-5 flap uplock

Post by krautman67 »

Thanks a TON Jeremy!
I inspected the flap bellcranks today. The left one has a vertical play of just over a half inch, it feels like there is no bushing in there. No doubt this is where all the slop started. Aircraft was always hangared (minimal wind pounding the flaps), but it is 43 years old. Time for a bit of maintenance. I will share photos once I have the unit out. I’ll order the parts after I have it all apart. I would never have checked this without your guidance. Great forum!
Carl
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Re: M-5 flap uplock

Post by maules.com »

If the pivot holes in the bracket are slightly worn then drill larger and use a next size bolt and custom bushing which will have more bearing surface than the original.
Jeremy
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Re: M-5 flap uplock

Post by 7336C »

Dear All,

Thanks for your posts in this topic. Since it turned out that the modification of my flap system is unofficial I decided to revert to the original flap control system with flap limiting cables. I already ordered some parts but it looks like I need to replace some parts as well, especially the flap bellcranks due to the extra holes drilled into them. I managed to get an untouched bellcrank for the left hand wing but still looking for one for the right wing. Do you have any source I can get used parts even from salvage aircrafts? They can bee still good but cheaper than the OEM parts. Any advice would be appreciated. Thanks a lot.
Zsolt
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krautman67
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Re: M-5 flap uplock

Post by krautman67 »

I finally removed the flap bellcranks today. Although the play in the bushings was not as bad as what I felt by simply moving it up and down as Jeremy suggested. It does however, look like the entire bracket was “rolling” up and down under load, as you can see in the attached photos. The flap cable is not in a direct line with the flap actuator rod. In other words, the torque applied by the cable, through time, forces the bracket in a downward direction. Since that bracket has such a narrow flange area, it simply does not have enough vertical re-inforcment. The bracket also looks bent.
The question is, is there an updated bracket available, or just make a new one with a bigger base, where it contacts the rear spar.

[url=https://postimg.cc/Xp53w8yd][img]https://i.postimg.cc/Xp53w8yd/5880-FBE4 ... 0-F6-B.jpg[/img][/url]

[url=https://postimg.cc/QK9DYgYL][img]https://i.postimg.cc/QK9DYgYL/7-EE4-ABD ... 427-D2.jpg[/img][/url]

[url=https://postimg.cc/XXpnv3j2][img]https://i.postimg.cc/XXpnv3j2/C2092-E67 ... 1-DF27.jpg[/img][/url]
[url=https://postimg.cc/Y4GTzhxd][img]https://i.postimg.cc/Y4GTzhxd/8-D067-FD ... 0-FCFE.jpg[/img][/url]
Last edited by krautman67 on Fri Mar 05, 2021 12:14 am, edited 2 times in total.
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Re: M-5 flap uplock

Post by Rezrider »

I removed my flap up lock tabs at this year's annual since they were getting bent and binding up in the slots. The metal tabs seemed pretty flimsy and the previous owner had them installed. I made foam flap locks that I install when parked outside in windy conditions.
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