Electric Flaps Troubleshooting

[mike_elliott]

56 minutes ago, LANCECASPER said:

Follow up. There are two relays for the flap actuator, one that controls the up circuit, one that control the down circuit. I swapped relays and got the flaps up and now the down circuit doesn't work so it must mean that the one relay is bad. I ordered two new relays since they are both the same age. I'll find out for sure when I put them in. For once there's actually a cheap part for an airplane.

http://www.alliedelec.com/schneider-electric-magnecraft-w67rcsx-3/70184966/

Great find! I think Mooney wants something like 2K to replace the entire board.

[LANCECASPER]

On 2/13/2017 at 11:25 AM, LANCECASPER said:

Follow up. There are two relays for the flap actuator, one that controls the up circuit, one that control the down circuit. I swapped relays and got the flaps up and now the down circuit doesn't work so it must mean that the one relay is bad. I ordered two new relays since they are both the same age. I'll find out for sure when I put them in. For once there's actually a cheap part for an airplane.

http://www.alliedelec.com/schneider-electric-magnecraft-w67rcsx-3/70184966/

Final follow up (hopefully) . . . after looking over the relay that I pulled, it was definitely burned.

So when the new relays came in I replaced both relays for a grand total of $43.68 with tax and shipping and everything works great now . .  and yes I'm replacing the tied up string with a zip tie and yes there's a black plastic cover that goes over the relays.

[mike_elliott]

2 minutes ago, LANCECASPER said:

I'm replacing the tied up string with a zip tie

Good avionics guys use this "string" instead of zip ties, as zip ties tend to shred your arms when they are not properly trimmed, and the guys that use them usually don't properly trim them.

[LANCECASPER]

Ah, thanks for that . . the string will stay.

[Yetti]

Pro tip if you choose to use ty wraps is to cut them with fingernail clippers.  It rounds the edges off.   Or Snap on has some small flush cut dykes that will remove harmful edges.

I have two pairs that have a nose broke off one of the cutter.  If you drop them on pavement the nose breaks.

[Vance Harral]

The other reason to be careful with zip ties is the serrations that the lock piece clicks into can act as a saw over time, cutting wiring insulation and even metal.  I use them in places I can see on a normal preflight or oil change, especially if I can put some electrical tape around the place they're installed.  But I'm less prone to use them in places that only get looked at during annual.

If you really prefer zip ties, good cutters and care in using them are worth the extra time.  Another good trick is to put some heat shrink tubing over the portion of the tie that will be tight against the wire/metal/whatever when it's tight.  That buys a little bit of protection against the sawing action.  But it requires a good estimate of what the used length will be once everything is pulled tight.

[ArtVandelay]

If you are getting sawing action, then you need to tighten the zip tie. No movement, no sawing.

[Vance Harral]

8 hours ago, teejayevans said:

If you are getting sawing action, then you need to tighten the zip tie. No movement, no sawing.

Pulling a zip tie tight enough to ensure it never moves - especially in a vibration-prone environment - is likely to damage the thing you're securing with the zip tie in the first place.  Certainly true of electrical wiring, sometimes true of cables and other structures.

[ArtVandelay]

Pulling a zip tie tight enough to ensure it never moves - especially in a vibration-prone environment - is likely to damage the thing you're securing with the zip tie in the first place.  Certainly true of electrical wiring, sometimes true of cables and other structures.

In planes or boats I've never seen a zip tie damage electrical wiring unless is was stupidly installed at a 90° bend instead of securing the leads into the bend, or secured to the wrong structure like when my MSC kept securing the gear down wire to the non moving frame so every time the gear was retracted it stress the wire and would break.

[Vance Harral]

There are certainly right and wrong ways to use them, including buying ones rated for the heat/light they're exposed to, and using appropriate tension and cutting methods.  To be clear, I'm not "anti" zip-tie, just advising reasonable caution, especially in areas you don't see frequently.  This is of course true for any method of securing wires, not just zip-ties.

For anyone truly interested, AC43-13 Chapter 11 has specific guidance on securing aircraft wiring, see in particular 11-96 (a), (b) and (o); and 11-146.  The big no-no is securing wiring to structure without some sort of stand-off.  Adel clamps provide that standoff inherently by design, and hence are arguably the gold standard for securing wiring.  Some people interpret that guidance as an FAA "rule" prohibiting zip ties in various applications, but I'm not one of them.

[N201MKTurbo]

I have a friend who is a lacing cord zealot. Every time he works on my plane he cuts off all the ty-raps and laces it up. I don't mind.

[N201MKTurbo]

From Wikipedia:

Cable ties were first invented by Thomas & Betts, an electrical company, in 1958 under the brand name Ty-Rap. Initially they were designed for airplane wire harnesses. The original design used a metal tooth, and these can still be obtained. Manufacturers later changed to the nylon/plastic design.

[N201MKTurbo]

The down side of lacing cord.

Even the best waxed lacing cord will slip on Tefzel wires. I have found that if you tie your starting knot around the bundle and then put a Ty-Rap right next to the knot with the string going under the Ty-Rap knot it will not slip. The Ty-Rap will get tight enough to slightly cold flow the Teflon and bite into it. Then run the lacing cord to the other end of the bundle and tie it off. Then put another Ty-Rap just before the knot. This way you get the best of both worlds.

[Mark Pavinich]

Also to note -- if it is really cold out and flying with temps around -20C or colder, all that dirt, grim, grease, carbon dust (from the brushless motor) and improper lube thickness will make thee switch stick (get stuck) in the wrong positions, which can also keep your flaps from operating until you get to warmer temps.

From my understanding a very thin lube should be used so that it doesn't thicken up during cold temps operations.  I think LS1 comes to mind.

[Sean S]

Ok, U have read this entire thread and a couple of others, and I am not sure @Marauder resolved his problem.  What was the final fix? I know someone having the same problem on their 75F. flaps intermittently will not retract.

[Marauder]

Ok, U have read this entire thread and a couple of others, and I am not sure @Marauder resolved his problem.  What was the final fix? I know someone having the same problem on their 75F. flaps intermittently will not retract.

I cleaned 40 years of gunk off of the components.






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[Sean S]

Awesome, no parts, just CRC! Thanks. Ill give it a shot.


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[Marauder]

Awesome, no parts, just CRC! Thanks. Ill give it a shot.


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A little toothbrush action might also help. You will need to pull the panel to get to the whole mechanism.


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[Yetti]

contact cleaner.  exercise the switch.  contact cleaner, exercise the switch

[GDGR]

So, just got my plane up for the second time after having the starter replaced.... slowed down for downwind, gear down, flap switch.... flaps.... flaps down..... flaps wont drop.... checked breaker. Nope. Decided to land without flaps (thanks CFI for making me practice those a lot).

Landed, turned around to taxi. Looked. Flaps halfway down. What the? Tried the switch. Nothing. Shut down at the hangar. Can hear the flap motor activating, but no love. Won’t go up or down now, and are “hanging” in about the 20 degree position currently. 

Anyone feel it’s the relays? Any other thoughts? Planning on heading to the hangar tomorrow to remove the belly pan to try and resolve. 

[Hank]

Check the limit switches while you're at it. They don't always like really cold weather, and may need to be cleaned. 

If the motor is running, the relay us likely good. 

Edited January 12, 2019 by Hank

[GDGR]

Motor is “whirring” with switch. Fact that the flaps are now halfway down and hanging there, leads me to believe it’s a broken linkage somewhere. 

Had my 7 year old with me for her first flight. Didn’t have a lot of time to assess. Nor did I need the “Daddy’s plane is broken” comments returning home to my wife. Haha. 

Ill head back tomorrow and do some investigation. Photos to follow tomorrow 

[N201MKTurbo]

I believe there is a rubber coupler between the motor and the screw. It could have sheered. If it did you need to service the screw.

[GDGR]

1 minute ago, N201MKTurbo said:

I believe there is a rubber coupler between the motor and the screw. It could have sheered. If it did you need to service the screw.

I’m hoping I can assess without taking the belly skin off. But, I think it’s inevitable. The way it’s moving, leads me to believe it’s some sort of disconnect like that. 

Both flaps still move (with manual pressure) in sync, so they’re attached. The fact that the flaps dropped after landing makes me think it “jarred” down when the wheels touched. 

[N201MKTurbo]

4 minutes ago, GLJA said:

I’m hoping I can assess without taking the belly skin off. But, I think it’s inevitable. The way it’s moving, leads me to believe it’s some sort of disconnect like that. 

Both flaps still move (with manual pressure) in sync, so they’re attached. The fact that the flaps dropped after landing makes me think it “jarred” down when the wheels touched. 

It can’t jar down, the sheared coupling probably caught for a bit and spun the screw.

You have to take off the belly panel between the flaps.