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Flaps Failed


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I posted a couple of times about my flaps running a bit slow, and occasionally sticking.  I have taken to running the flaps fully up/down before taxiing, and since then haven't had any issue with them in flight.  My plan was to continue that regime until Winter and then disassemble the flaps and fix the issue then.  Yesterday while cycling the flaps before taxi the flaps were cycling fine and then stopped dead just before hitting 40°.  Once they stopped they wouldn't cycle in either direction, though the display was flashing like it was trying.  I tried by hand to "assist" the flaps why cycling, got in the baggage bay and made sure everything was lubed, but...nothing.  The flaps won't budge from about a 38° setting.

I think the actuator motor is failed or seized.  My plan is to disassemble the flaps mechanism this weekend and try to find the problem.  If it's the motor as suspected, I'll probably just try to order a new one rather that try to recondition the old one.  IIRC the new motor is something like $900...is there an alternate unit or source that is less expensive?

Also does anybody who's disassembled the flaps mechanism have any advice?  It looks like quite a PITA disassembly looking in the Maintenance Manual.  😢

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Hey Andy,

When you get ready to tear into it there is a pretty extensive thread somewhere here that one of the fellas tore down the whole flap control unit for inspection and re grease.  If I can find it ill post it here.

 

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1 hour ago, Vic said:

Hey Andy,

When you get ready to tear into it there is a pretty extensive thread somewhere here that one of the fellas tore down the whole flap control unit for inspection and re grease.  If I can find it ill post it here.

 

Thanks, I will look for it as well.  I seemed to recall that...can't remember which user (Madhatter?  FredG?). 

If anybody else has any words of wisdom I could use them...I have a feeling I'm walking into a buzzsaw on this one.

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A possible troubleshooting point...

I have noticed my flaps from the 40 and -6 positions can go one extra "click" downward and upward and get into showing --- on the display.  I think this is manual mode, but I thought you needed to go 180° from the 15° position to get there.  Maybe my issue is the switch or the stop and collar washer?  I've never needed manual flaps before so I've never used it.

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I replaced the switch in mine. I had a buddy that is always soldering stuff do it. The part was cheap and he said it was easy to do. Didn’t fix my problem though. Flaps work in manual but not preset.

Did loose all flaps once though and it ended just being a poor connection at the flap motor. A little wiggly and tightened the connection fixed it to where at least manual mode worked again.

Sure seems like flap problems are the #1 maintenance issue on these planes. Either you have had flap issues or you will. Trouble shooting is a pain and of course if you need a replacement board on the SW, they don’t make it anymore and you have to do some work to replace it with the new board.

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11 hours ago, FlyingMonkey said:

Question Tom...why put a separate 12v source on it instead of putting a meter on the spade connectors going into the motor to verify current?

Putting a meter on the terminals does not verify current, it verifies voltage. It is possible to have voltage without enough current to operate the motor. This would be due to a poor connection/relay/ or such up stream from the flap motor.

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11 hours ago, FlyingMonkey said:

Question Tom...why put a separate 12v source on it instead of putting a meter on the spade connectors going into the motor to verify current?

Putting a meter on the terminals does not verify current, it verifies voltage. It is possible to have voltage without enough current to operate the motor. This would be due to a poor connection/relay/ or such up stream from the flap motor.

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4 minutes ago, Tom Baker said:

Putting a meter on the terminals does not verify current, it verifies voltage. It is possible to have voltage without enough current to operate the motor. This would be due to a poor connection/relay/ or such up stream from the flap motor.

Got it, thanks.

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I had a little time to do some troubleshooting this evening.  I found that there are 0.00v getting to the spade connectors on the motor, so it looks like an electrical issue.  There is 13v+ getting to the flap breaker connections.  The switch appears to be working properly in that the numbers match the flap positions when changed and the red and green LEDs are lit like it's trying to move the flaps.  

Tomorrow I'll trace the wires from the motor for continuity and make sure there's not something dumb like a chafed wire.  Otherwise it looks like I'll have to pull the flap board and check it.  Does anybody know the best way to remove the switch to get the board out, and know what points to put a multimeter on the board to test for proper operation? 

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10 hours ago, FlyingMonkey said:

Does anybody know the best way to remove the switch to get the board out

I believe our SW's are very close in manufacture date, it's been several years but should be as follows:

1 - remove the 4X panel screws attaching to mushroom

2 - remove flap selection switch handle/knob (set screw?)

3 - remove the flap switch collar or ring holding to board?

4 - remove the 2x screws & nuts above the flap led indicator (through bolt through lens and board)

That should have the board free of everything less the electrical wires.  Take your time and if something is not moving freely, find the snag or what's still retaining it, should not take effort.  

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2 hours ago, GrassStripFlyBoy said:

I believe our SW's are very close in manufacture date, it's been several years but should be as follows:

1 - remove the 4X panel screws attaching to mushroom

2 - remove flap selection switch handle/knob (set screw?)

3 - remove the flap switch collar or ring holding to board?

4 - remove the 2x screws & nuts above the flap led indicator (through bolt through lens and board)

That should have the board free of everything less the electrical wires.  Take your time and if something is not moving freely, find the snag or what's still retaining it, should not take effort.  

Thanks Darrell.  Any idea how to check/test the board once it's out?

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From what my overall observations are on others before you, the board will have solder issues to wires / components?  I'd look with an eagle eye for physical issues first, hope it's just a resolder situation.

And I was out for a hop this morning and realized for my item 3 above I was thinking about the ignition switch.  The flap switch is just a standard small nut on the post.  And when you take that apart is when you'll access the ring with tang for allowing rotation into the manual mode - it's obvious when you get into it...

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I had a relay board fail when a solder connection on the board broke.  I wiped the lacquer from that joint and re-soldered.  Like Darrell said, takes a very close inspection of the back side of the board to find.  Also, each of the wires to the relay board is held in place with a screw terminal.  A long screwdriver with the proper tip (straight slot, not Philips) lets you check to see if the connections are tight without removing the board from the firewall.  When I removed mine, one of the rivnuts on the firewall spun, made getting the thing out a real PITA.  

By casual observation, it seems that the relay boards have more problems than the board on the panel.  

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Well, thanks guys for all the info and tips!  Especially thanks to Corey for mentioning the relay board…I fixed the issue, it was a loose wire coming off the relay board.  I set the flaps to move and jiggle the wires and presto, the flaps started moving.  I loosened and re-tightened the screw connectors on the wires and then could not reproduce the problem when jiggling wires.  Hopefully that does it, if it recurs I know right where to look.
 

So one failure fixed the best possible way, quickly and at no cost!  Until the next failure, then…

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I spoke too soon.  I took a flight yesterday and the flaps failed again when I tried to put them down from 15° to 30° for landing.  Once on the ground they worked perfectly, so I'm wondering if I might have a ground issue...I have seen other electrical devices act squirrelly in the air and fine on the ground when there was a ground issue. 

I guess I'll check all my grounds, re-tighten all the wires into the relay board, and see how that goes.  I really hope there's not a crack or other issue in the relay board.  Are those boards still made, and/or easily repairable?

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The boards for the SW are no longer made. The new single board for the newer LS is available and can be made to replace the dual board from the SW. Flight Design said it takes some work for the mod to the single board though.

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51 minutes ago, Towner said:

The boards for the SW are no longer made. The new single board for the newer LS is available and can be made to replace the dual board from the SW. Flight Design said it takes some work for the mod to the single board though.

Hmm, so the relay board *and* the controller board both would get replaced?  I bet that is a pricey option.  I have a pretty good electronics guy, I'd let him try to repair the relay board first. 

BTW, why did FD put hard-as-rock sealant over the screws the hold the wires to the board?  So annoying to get that sh*t out while contorting yourself inside the panel.

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