Broken flap handle

How to keep the Cessna 170 flying and airworthy.

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Broken flap handle

Postby Terrance Lucas » Tue Sep 08, 2009 12:04 am

I was flying into Oakdale CA(home) on downwind at 90 and pulled first notch of flaps and every thing was normal but when I pulled next notch the handle broke at the base. My question has to do with the proper way to repair this problem. Should the handle be replaced or is it proper to have the handle welded. Is the handle available for a 1949 170a. Any expert advice would be greatly appreciated. This is my first post to the group. Owned N9068A 21 years.
Thanks
Terry Lucas
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Re: Broken flap handle

Postby EZFlap » Tue Sep 08, 2009 4:26 am

A plain steel part like the flap lever should be repairable by welding, and is allowed per AC 43.13.

However, I do recommend that you remove the entire handle, have it blasted clean and checked for cracks thoroughly.

Then have it welded on a bench (instead of on the airplane), re-primed / painted and then re-installed.

The most important thing is that this is not a very common failure, so you should figure out why the handle weakened or cracked in the first place.

If you do decide to replace the handle with another one instead of repairing the broken one, please contact me before you throw out the broken handle because I would like to have it for a product display.

Bill
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Re: Broken flap handle

Postby Bruce Fenstermacher » Tue Sep 08, 2009 10:10 am

Flap handles are becoming a thing to inspect much closer these days. Reports as documented elsewhere here are of failures in the release mechanism and rivets that hold stuff together. I had the impression, probably incorrect, that the problems were with the B model handle but that the earlier handle was probably built very similar.

When you say it broke at the base what exactly do you mean. A picture here would be worth a thousand words and would be the best and much appreciated way to spread the word.
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Re: Broken flap handle

Postby c170b53 » Tue Sep 08, 2009 5:39 pm

The "A" handle is smaller and less complicated than the "B". The one I worked on wobbled quite a bit and the bushings for side play were not as depicted as per the IPC. Yet it may have been an IPC mistake, so a few pics would be as Bruce mentioned very helpful.
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Re: Broken flap handle

Postby gahorn » Tue Sep 08, 2009 6:38 pm

Chances are that a small crack propagated un-detected and your deployment of flaps was the final straw that day.

All the flap handles are light-gauge sheet metal and tubes welded up into the assembly.
Wherever those welds exist ...(and by the way...quite a variation exists in the "quality" of those welds)....
...there exists a stress-riser due to the temperature striation that occurs there. Vibration embrittles that
area and a hairline crack can develop and go undetected for quite a while. I've seen some cracks that the
owners knew about...but chose to ignore because they weren't thinking of the consequences that might
develop should failure occur at an inopportune moment. (I.E. What if it broke while practicing a full-flap
stall? Or during a go-around that prevented retraction? etc etc.)

Let this msg thread serve to inspire everyone to re-asess the myriad of small "squawks" or "near-squawks"
we come to accept as minor defects in our equipment.

The 170 and 170-A models have a slightly different dimensional set-up from the B-model...but they ALL
use similar materials and methods in that contraption to deploy flaps...INCLUDING that rod-and-latch mechanism
which failed and I documented in the recent 170 News article.
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Re: Broken flap handle

Postby Terrance Lucas » Wed Sep 09, 2009 6:25 pm

Hello Group
I removed the broken flap handle and took a picture.
Terrance Lucas
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IMG_5376.JPG
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Re: Broken flap handle

Postby wingnut » Wed Sep 09, 2009 8:55 pm

Thanks for the picture Terrance.
I just looked at flap handle to get a better idea. There are no welds in the area where the crack began, but the radius of the cutout area is pretty small. I do see where a larger radius would be good, but I think this handle may have seen some abuse during it's life. I noted that the only way I could get any significant force/leverage to stress this area was if I pull back on the handle, past the last cog, until it contacts the aft end of the slotted panel and continue pulling.
I visualize a large back seat passenger grabbing the deployed handle to assist egress.
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Re: Broken flap handle

Postby DaveF » Sat Sep 12, 2009 2:47 am

Here's a cracked flap handle on a B model.

flaphandlecrack.jpg
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Re: Broken flap handle

Postby gahorn » Sat Sep 12, 2009 8:32 am

My own flap handle had a poorly-executed weld on it's spine which Del Lehmann and his co-conspirator Mike repaired for me. There seems to be a great deal of variance on the quality of welds on this part, throughout the fleet.

Here they are again, setting up to do some welding on it.
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Del and Mike weld flap lever.JPG
'53 B-model N146YS SN:25713
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Re: Broken flap handle

Postby Terrance Lucas » Sun Sep 13, 2009 12:15 am

Hello Group
Thank you all for responses to this post
I found a flap handle for my 170a on barnstormers in Idaho. I'm hoping to start with better parts than the one that broke. When it broke as George says it made it imposible to retract the flaps which really could cause some trouble at the wrong time. I will make it a more important part of my inspection from now on. I also learned that saying " OH #*%@! I JUST BROKE THE FLAPS " was pretty hard on my wife.
Thanks for a great association
Terrance Lucas
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Re: Broken flap handle

Postby N2255D » Wed Apr 14, 2010 7:39 pm

Another B model with a crack on the flap handle. It could not be seen it from the outside because the paint had not cracked yet. I was cleaning under the floor since the engine is off and happened to see a black line inside. After taking the paint off the 3/8" crack was obvious.
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IMGA0116.JPG
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Re: Broken flap handle

Postby blueldr » Wed Apr 14, 2010 7:47 pm

It looks to me like a welding job with the installation of a light strengthening gusset. That is, if it doesn't show other excessive metal deterioration through corrosion or rusting.
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Re: Broken flap handle

Postby tamarack » Thu Apr 15, 2010 3:26 pm

Cracked flap handles as in the above pictures don't seem to be uncommon in the 170B-180 and 185 series. Strangely enough, the cracks that I see while inspecting have always been on the right hand side of the handle.

Thanks for posting the pictures!

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Re: Broken flap handle

Postby N2255D » Thu Apr 15, 2010 5:27 pm

I already had it repaired when I posted. The crack appears to be in the same location and about the same size as the previous picture so I wanted everyone to know that you might have to look inside to see the crack. The outside of my handle had a lot of layers of paint. The inside was just one layer.
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