Maule M-6 flaps issue

ajak · Post by **ajak** » Thu Sep 03, 2015 10:21 am

So I was out burning avgas last night and when I selected anything more than zero flaps, I noticed visually that they weren't dropping all the way to match the detent position. The handle and detents felt like they were working fine. When selecting an additional notch of flaps, I could see the flaps physically extending just a bit, but not nearly as much as they should have. As soon as I touched down (with the flaps handle locked in the detent at 48 degrees), the flaps extended fully to match the handle/detent position (after overcoming air pressure?). I shutdown and exercised the flaps on the ground- all appeared completely normal. But when I went up again, they did the same thing as before. No unusual feeling on the flap handle, or unusual forces.

I understand from reading through the forums that the M-6 doesn't have a flap retract assist spring. But it sounds like they do have a "cartridge" type safety over speed spring bungee- does it sound like a weak spring could be the culprit here? Seems like it's the only (intentionally) "springy" component in the flap rigging of the M-6. I believe all the rigging was replaced before I bought it recently, and I've been paranoid about not overspeeding and overstressing the flaps - I never start dropping them until I'm at least 10 kts below the top of the white arc. New to me airplane so I'm still on the steep part of the learning curve here - thanks for any ideas!

AJ

pilot · Post by **pilot** » Thu Sep 03, 2015 12:06 pm

You do have a red shock absorber-looking thingy in the flap down cable that prevents the flaps from deploying at overspeed conditions. Sounds like I would look there first, check the tension on it and let us know what you find.

Steelroamer · Post by **Steelroamer** » Thu Sep 03, 2015 12:49 pm

My M-6 (1984) has the spring cartridge in it. if you take the panel off at the rear of the cabin it sits almost dead center. when I get home I will dig out a picture and post it if you would like. I read (somewhere) that the sping prevents full extension of the flaps until 55mph. mine is almost exactly that.

hope this helps and let me know if you would like the picture

Roamer

maules.com · Post by **maules.com** » Thu Sep 03, 2015 10:02 pm

Try not to exceed 90 mph for 24 deg, 80 mph for 40 deg, and 70 mph for 48 degrees. These are max speeds.
In flight set 48 degrees at about 65 mph and make a mark on inside of window adjacent to flap trailing edge, then slow to 54 mph and place a mark which is where the flap should have reached full extension. Speed up slightly and you will see the flap rise up once above 55 mph.
If this is not so, then your spring bungee cartridge may be tired.

ajak · Post by **ajak** » Thu Sep 03, 2015 11:52 pm

Thanks all! Great info. Just got home from work but will open up the back and look at the spring bungy tomorrow and will report on what I see...

AJ

ajak · Post by **ajak** » Sun Sep 06, 2015 8:39 pm

Well, took a look at the spring bungee last night, and couldn't see anything immediately-apparent wrong with it. Still tests fine on the ground, with the appropriate travel at each setting, and doesn't feel like there's any unusual give or slop in the system. So I marked the 48 position on the window with tape, and up I went to burn avgas.

Even below 55 mph, I couldn't get more than what appears visually to be somewhere between first and second notch of flaps. No further extension even when slowing to a stall, below indicated airspeed. But it still extends all the way to the correct 48 position as soon as I land.

Going to get together with my A/P hopefully in the next couple of days and take a look at cables and fittings to make sure there isn't some other source of slop, and see what else we can make out on the spring bungee...

pilot · Post by **pilot** » Mon Sep 07, 2015 7:04 am

Congrats on finding the problem!

ranchhopper · Post by **ranchhopper** » Mon Sep 14, 2015 6:40 am

I have the same problem on my M-7-235,
the flaps fully extend only during the flare, makes landing a special event as the flaps extend to 48° you get an up drift where you don't expect it.
Checked cable tension and found that at the recomended 60lbs tension the spring cartridge extended about 1". Then on ground I was able to push the flaps back by hand about 20° or so.
Conclusion the spring cartridge looks weak. Can anyone say at what tension this cartridge is designed to start extension?
ranchhopper

Duane · Post by **Duane** » Mon Sep 14, 2015 12:53 pm

It should start compressing the spring at approx 150 lbs of force.

ajak · Post by **ajak** » Sun Sep 20, 2015 9:44 am

Ranchhopper, I'll be very interested to hear if replacing the spring solves the problem for you. I haven't had a chance to further address mine yet.

AJ

ajak · Post by **ajak** » Thu Aug 04, 2016 10:21 am

Just to bring closure to this thread, it looks like a new spring cartridge from Maule solved my flap extension issue. With flap cable tension set somewhat on the lower side of the Maintenance Manual spec (60 +/-10 lbs), I now get full flap extension somewhere between 50 and 55 mph IAS.

AJ

Mountain Doctor · Post by **Mountain Doctor** » Thu Aug 04, 2016 12:00 pm

Thanks for the information; glad you're good to go. I suspect mine is weak but it's good enough for the time being.

Wyflyer · Post by **Wyflyer** » Thu Aug 04, 2016 2:13 pm

I learned much from this thread, thanks

Andy Young · Post by **Andy Young** » Sun Aug 20, 2017 9:54 am

Picking up an old thread here.
Same problem on my M-6-235. Correct flap deployment on the ground, but in flight couldn't get more than about 25* in the last notch until slowing to 45 mph. Even at 45 mph, only get 40* deployment. I get 48* right at touchdown.

Changed the spring cartridge; it's better, but still not correct. I can now get 40* at 52 mph, and get a max deployment of about 43* at 45 mph. Slowing to 40 mph doesn't get me any more than that, although I get to 48* right at touchdown as before.

I have the early M-6 wing, with the longest flaps. Is there a different spring cartridge for that flap, to compensate for the the greater flap area? Is it possible I was sent the wrong cartridge? I know I can ask the factory tomorrow; just thoug someone here might know today.

ajak · Post by **ajak** » Sun Aug 20, 2017 11:04 am

FWIW I found that after initially installing the new spring cartridge on my M-6, full 48 degree flap deployment also still didn't happen until pretty much right at stall. As per my maintenance manual, the flap cable tension spec is 60 +/-10 lbs. I found that I had to adjust it to the low end of the spec. I now see full 48 degrees of extension just above 50 mph IAS.

I've also wondered if perhaps the root of the issue is that the M-6 spring cartridge was simply carried over from the M-5 with smaller flaps, and maybe just isn't strong enough for the job. But I guess the flip side of that is that the larger flaps on the M-6 maybe use most of the same structural components of the M-5 so maybe the system needs more protection from the increased aerodynamic loads.