Howard DCA rigging questions.

[gismo]

A friend has acquired a Howard DCA-15P and is in the middle of an annual inspection with the help of an AI who has never seen a Howard before. One area of confusion is how to set the tension in the control cables for ailerons and flaps, both of which are moved via steel cables (wire rope). There is one turnbuckle in each of the cables running from one wing to the other (one for flaps and one for ailerons) as well as one in the cable that runs from the actuator near the firewall to the right flap, and one in the aileron cable running from the yoke to the right wing. The diagram for the cables indicates that the tension in the two overhead flap cables is supposed to be 100 +- 10 lbs. The flap cables attached to the actuator are marked 125 lbs (up) and 40 lbs (down). All aileron cables are marked 50 lbs.

A number of questions have come up:

1> How can you have 125 lbs in the flaps up cable just aft of the actuator and only 100 where the same cable passes over the top of the cabin?

2> Assuming that the unbalanced weight of the flaps produces some tension on the up flaps cables, how could you get equal tension in the two overhead flap cables given that one carries the weight of two flaps and the other only one?

3> Do the flaps have local stops? IOW is there something that limits flap travel (either direction) at the flap itself or is the travel controlled soley by the actuator. BTW you should see the sender for flap position. It's an electric fuel gauge sender!

4> If there are local stops for the flaps, should the tension be set when the flaps are against the up stops?

5> The tension in the aileron cables seems to be different, and this makes sense to me since the crossover cable carries the weight of both ailerons, and the actuator cable to the right wing carries none if both ailerons generate the same torque force.

Any insight into how this is supposed to be done would be greatly appreciated by my friend (and I might get to fly this rare bird if I help figure it out).

 

[Diana]

A friend has acquired a Howard DCA-15P and is in the middle of an annual inspection with the help of an AI who has never seen a Howard before.

Oh, Lance you do bring up the memories.

My Dad bought a Howard DGA-18 years ago when we lived in Memphis. Long story. I'll try to attach some pictures. There is a Howard DGA-18 on display at the museum at Fayetteville, AR that is one N number away from the one we used to own. Our old Howard is going to be rebuilt by a gentleman in Chicago. He still has the parts in a hangar ready to be rebuilt. I have his email address if you want it.

There is a gentleman in AR that Chip knows who is experienced in Howards. If Chip doesn't respond, I'll try to figure out how you can connect with him.

 

[Diana]

A friend has acquired a Howard DCA-15P

BTW, do you know what DGA stands for? This forum editor will bleep it out

 

[Diana]

Any insight into how this is supposed to be done would be greatly appreciated by my friend (and I might get to fly this rare bird if I help figure it out).

Hey, I hope you get that ride, and if I was of any help, can I get a ride, too?

 

[Tom-D]

BTW, do you know what DGA stands for? This forum editor will bleep it out

Darn Good Aircraft

 

[Diana]

Darn Good Aircraft

Yep

Have you worked on any of them?

 

[Dan Deutsch]

3> Do the flaps have local stops? IOW is there something that limits flap travel (either direction) at the flap itself or is the travel controlled soley by the actuator. BTW you should see the sender for flap position. It's an electric fuel gauge sender!

Lance as will be avident in about 2 nano-seconds, I have no idea.

However a WAG is that the control surfaces may need to be pinned or secured during the rigging process.

Lot's of airplanes require this. One clue would be that any pulleys in the system have a drilled hole in the pulley and in the bracket. Usually a pin is inserted basically locking the pulley to the bracket.

Googling got me some results on maintenance facilities. A call to one of them or the EAA might put you on the right track.

 

[Tom-D]

It sounds to me like some one is reading the manual wrong. But with out reading it my self I can't tell.

Why is the cables being re-rigged? control problems?

 

[gibbons]

Lance,

The guy Diana is talking about is Jim Younkin in Springdale. He may or may no know the answers to your questions. Feel free to use my name if you have any trouble getting him on the phone - don't know that it will help but I doubt that it will hurt.

His phone number at TruTrak is 479-751-0250.

Chip

 

[gismo]

It sounds to me like some one is reading the manual wrong. But with out reading it my self I can't tell.

Why is the cables being re-rigged? control problems?

Nope, I asked the same question. They are just trying to get the cable tension correct per the "manual" they have. The owner doing the work thought that he could affect the tension in one aileron cable relative to another by changing the turbuckle in the line that runs from the right to the left wing. This seems unlikely to me unless the ailerons are pinned, which they weren't. Fortunately he didn't move the turnbuckle much.

 

[gismo]

Lance,

The guy Diana is talking about is Jim Younkin in Springdale. He may or may no know the answers to your questions. Feel free to use my name if you have any trouble getting him on the phone - don't know that it will help but I doubt that it will hurt.

His phone number at TruTrak is 479-751-0250.

Chip

Thanks Chip, I'll pass it on.

 

[gismo]

Lance as will be avident in about 2 nano-seconds, I have no idea.

However a WAG is that the control surfaces may need to be pinned or secured during the rigging process.

Lot's of airplanes require this. One clue would be that any pulleys in the system have a drilled hole in the pulley and in the bracket. Usually a pin is inserted basically locking the pulley to the bracket.

Googling got me some results on maintenance facilities. A call to one of them or the EAA might put you on the right track.

I think I do remember seeing a 1/4" hole in the pulleys attached to the belcranks. I'll bet they are supposed to be pinned.

 

[gismo]

Hey, I hope you get that ride, and if I was of any help, can I get a ride, too?

Works for me, as long as you come up here. He also has an AT-6 that you might get a ride in and there's always the Porterfield.

 

[Tom-D]

Have you worked on any of them?[/QUOTE]

Nope just helped junk a couple of them.

 

[Tom-D]

I think I do remember seeing a 1/4" hole in the pulleys attached to the belcranks. I'll bet they are supposed to be pinned.

DO NOT adjust cable tention with pins in these holes!!!! tension the cables then CHECK to see if a pin will fit. IF you adjust cable tension with the pin in the hole it will cause the pin to stick and maybe break the shiv.

 

[Tom-D]

Nope, I asked the same question. They are just trying to get the cable tension correct per the "manual" they have. The owner doing the work thought that he could affect the tension in one aileron cable relative to another by changing the turbuckle in the line that runs from the right to the left wing. This seems unlikely to me unless the ailerons are pinned, which they weren't. Fortunately he didn't move the turnbuckle much.

If it was flying correctly they should have left it alone. Temp has a great deal to do with cable tension. If the aircraft is not at the same temp, as when the cable tension was set it will never be the same.

Aircraft follow the same train of thought as manure, If it don't stink don't stir it.

 

[Diana]

Works for me, as long as you come up here. He also has an AT-6 that you might get a ride in and there's always the Porterfield.

You never know, I must might run up there someday.

If I had a choice of which three airplanes, flying with you in the Porterfield would be at the top of my list.

 

[gismo]

If it was flying correctly they should have left it alone. Temp has a great deal to do with cable tension. If the aircraft is not at the same temp, as when the cable tension was set it will never be the same.

Aircraft follow the same train of thought as manure, If it don't stink don't stir it.

I pretty much gave him the same advice already. Unfortunately he still thinks this is something that must be perfect at inspection time. Of course when I mentioned the tension vs temp charts, he said he wasn't concerned about that because the temp would be different when he flew anyway. Sigh.

 

[gismo]

You never know, I must might run up there someday.

If I had a choice of which three airplanes, flying with you in the Porterfield would be at the top of my list.

I hate to admit it but a ride in the Howard or an AT-6 would likely be more fun. But your welcome to fly the Porterfield any time.

 

[Dan Deutsch]

Unfortunately he still thinks this is something that must be perfect at inspection time. Of course when I mentioned the tension vs temp charts, he said he wasn't concerned about that because the temp would be different when he flew anyway. Sigh.

Wel... Shoulda got the manual first. Shoulda got the procedures first. Shoulda talked to someone who's done it first. Shoulda checked the tensions using the right temp factors first. Shoulda left well enough alone.

But now that Pandora's box is open he's gotta see it to the end.

Pretty clear that the correct answers won't come from here.

Classic / antique procedures can be hard to come by.