Flap Intermittent Problem
 

Hello All. I have a 1975 337G. Went flying today and after landing noticed that the flaps won't retract fully. Looks like they are stuck at about 1/3 extended. When I move the flap lever to 2/3 extended the flaps drop down some more. When I move the level to full extended they do not go any further than about 2/3. When I retract the flaps no matter what I do they will not close beyond about 1/3 extended.

Any thoughts? The only thing of note is that the gear was swung by the mechanic a few days ago? I am about to pull out the service manual but was hoping that someone on the forum might know what to do.

P.S. I looked at the micro switches and connectors behind the flap lever and everything looks tidy.....no corrosion or frayed wires that are obvious.

Thanks,
Chris

I would check the push pull cable that moves the switches on the selector. We had one freeze up and it made the flaps do strange things

Thanks Kim....just looking over the service manual and I believe you nailed it!

Thanks.

Chris

I have had to replace that follow up cable before because it gets corroded and sticky. You can try to pressure lube it first as that has helped in some cases.

Flap Intermittent Problem
 

Thank you Herb....any chance you know a place to purchase the cable that is reasonable. Cessna wants about $550.00.

Cheers...

chris

Do you have the part number?

Flap Intermittent Problem
 

Herb,

The part number listed in my book is : S1244-20: Control-Push-Pull Cable

Thanks.

Chris

Contoller dot com - parts search
 

http://www.controller.com/list/parts...-20&pst=starts

Did you check with Don Nieser at Commodore Aero? He may have a surplus unit. His direct line is 405-503-4686

The cable that I sourced was from Preferred Air Parts but they don't show any stock today

Flap intermittenjt problems
 

I have new flap cables for all 337 Skymasters as well as most other cables. I try to price the parts I sell at 50% to 55% of Cessna's prices, so give me a call at 405-503-4686 or
nieser.02.337parts@juno.com

Flap Intermittent Problem - Resolved
 

So you guys were right. It was the flap Control-Push-Pull Cable. After troubleshooting I found that the cable was frozen. After taking down the headliner it was obvious what the problem was. With the cable being frozen, the flap motor/actuator over time pulled the inner stainless spiral cable wrap away from the black outer coating and threw everything out of wack. I was able to pressure lube the cable and got everything working again....however, although the flaps are working as they should, the indicator at the flap lever is not traveling the full distance up and down....that said, I purchase a new cable from Don Nieser (405-503-4686 or
nieser.02.337parts@juno.com) and expect to have the cable in the next few days.

Thank you to everyone who helped resolve this problem. I hope this thread helps others down the road.

P.S. if you have a service manual and parts manual I suggest that you research how the flap lever interacts with the flap motor. It is rather ingenious. I bet most out there think the flap lever is a simple device that turns comes in contact with micro switches....you'll be amazed to learn the the flap lever moves a cam that does come in contact with an up or down micro switch...but, what makes it ingenious is that as the flaps move, the flap lever control push-pull cable actually rocks the flap lever mechanism thereby moving the location of the up/down micro switch. This interconnection between the flap motor/actuator and the flap lever makes it possible to have some what of an infinite number of flap settings between the upper and lower limits......

Cheers.
Chris

Thought I would add to this...

I had very similar issues with my flaps as the original post.
Replaced the flap control cable with a new unit from Don Nieser.

Pulled my old one out and lay it on the hangar floor, it felt smooth as silk.
However, as soon as I put the bends back in it, i felt it immediately bind up.
For the price of these things, its not worth messing with it to try and re-lube the cable and carry on. They do run through a weird series of bends to get from the front of the airplane to the back.

Its a fairly straightforward job, but does require the removal of about 90% of the interior - get ready to spend some time laying on your back under the instrument panel.

Only real gotcha is the rigging. Once you get the approximate distance of the rod ends sorted out, there is a slot in the flap-motor end of the cable that allows you to change the throw of the bellcrank. Takes a bit of trial and error to get the right amount of travel to allow the flaps to come full up.

Now she works like a charm, and retracts fully into the wing. I was actually shocked at how much... I rekon she'll be 5 knts faster!


Pics attached:
-The weird ass routing in the roof
-Up/down limit microswitches on the flap jackshaft. Cable attaches on the right side of pic, can see the bellcrank slot.
-Retracts nice and tight for MOAR SPEEEEEEEED!!