Flap linkage on 170A worn out.

airspeed · Post by **airspeed** » Thu Jun 26, 2014 2:00 pm

I'm in the middle of an annual on my 170A. The mechanic found a cracked flap control horn bracket. On further investigation he also found that all of the linkage parts were worn. Someone in the past had drilled out the 3/16" holes and replaced the 3/16" pivot bolts with 1/4" bolts. I don't know how long ago this was done as there is no mention of it in the logs. The holes in the control horns are egg shaped and dangerously close to the edge of the bracket. Long story short the mechanic thinks it's unsafe to fly. The further good news is Cessna no longer has the parts. So far we've not been able to find any in the after market.

I was surprised that I could not find any mention of this problem on the forums. My airplane only has 3334 hours on it and has not been abused. The linkage is pretty Micky Mouse in terms of bearing surfaces so I'm not surprised that it has worn. I would advise others to check theirs to be on the safe side.

Has anyone else out there been down this road?

hilltop170 · Post by **hilltop170** » Thu Jun 26, 2014 7:52 pm

I can't picture in my mind what parts are involved but I have had welded-in bushings installed in several pivoting parts along the way. Those bushed pivots will probably never wear out again, ever. Atlee Dodge in Anchorage did most of the precision welding on my parts. Or, if the parts are absolutely worn out and not repairable, Atlee Dodge might be able to recreate them as owner produced parts under your direction. They made new rudder bell cranks for my C-180 years ago that are still working fine.

bigrenna · Post by **bigrenna** » Fri Jun 27, 2014 12:14 am

delete

airspeed · Post by **airspeed** » Sat Jun 28, 2014 3:33 am

The linkage parts won't be that hard to make. I've contacted a structures rep at Cessna and he will try to get me copies of the production drawings. I can get the dimensions from the old parts, but the drawings should give specifics on the alloys used. I also need the dimensions of the bushing that the bellcrank pivots on. It controls the spacing of the bellcrank from the butt rib. The real bugger is the control horns riveted to the flaps. One is cracked and both are worn out. They are formed aluminum sheet and will be a pain to duplicate.

LBPilot82 · Post by **LBPilot82** » Tue Jul 08, 2014 4:31 am

Please keep us updated on what you come up with as my flap linkage is heading in the same direction.

Post by **GAHorn** » Tue Jul 08, 2014 7:07 pm

DaveF · Post by **DaveF** » Wed Jul 09, 2014 5:09 am

If you get your hands on actual Cessna production drawings, send copies to Bruce to put in the library.

jetguy · Post by **jetguy** » Sat Jul 26, 2014 5:06 pm

George....never knew you had so many children. Good looking family though,I have to say...

Post by **GAHorn** » Mon Jul 28, 2014 2:12 am

jetguy wrote:George....never knew you had so many children. Good looking family though,I have to say...

Yep they came from the ANDERSON part of the family!

George Anderson Horn

airspeed · Post by **airspeed** » Tue Aug 05, 2014 1:53 pm

I've not heard anything from Cessna yet regarding production drawings for the flap parts. Linkage or control horn. We are doing the rest of the work called out in the C100 SID that Cessna considers mandatory. Just got the wings back on and am installing new cables and pulleys. When all of that's done we will deal with the flap issue. At this point in time it looks like we will have to manufacture our own parts.

The control horn bracket is two aluminum stampings tack welded together. One could be made of steel quite simply, but the IA we are working with wants to form a new part from aluminum.

I'll update this thread and post pics when we actually get something done.

The International Cessna 170 Association