Door Catch and Door Handle Latch repairs

Joe Moilanen · Post by **Joe Moilanen** » Wed Jan 03, 2007 7:06 am

Sorry, I spaced out sending the pictures of the way I replaced my springs. WAY better than the original "mousetrap"ones. I'll email them to Doug so that he can post them.

Joe

doug8082a · Post by **doug8082a** » Thu Jan 04, 2007 1:17 pm

Got the pics. I'll post them tonight.

wa4jr · Post by **wa4jr** » Fri Jan 05, 2007 12:34 am

Uh-oh, this shopping trip for door latch/handle springs has me thinking of going the homebuilt route again so I can get my money's worth on parts. Hill Aircraft had the spring for the door handle....at $15 each, and the only outfit left in the country that has the latch spring is Avparts....at....are ya sittin down now....$25 each. Yes ladies and gentlemen, I paid $25 for each of two small pieces of spring steel

I see in the picture of the latch unit several posts up that someone had taken matters in hand and installed a standard coil tension spring...probably every bit of 50 cents. Instead of going back with AN470 rivets through the door skin into the latch end plate, I'll see if I can get a low-profile rivnut in there....so I will not have to drill out rivets again when my $25 spring breaks

Indopilot · Post by **Indopilot** » Fri Jan 05, 2007 12:52 am

The spring thing has been discussed before where it mentions the 120/140 web site having plans for making a jig to one of the springs. After following the plans I decided it wasn't to hard to make that one so I adpted the plans and made a jig for the other one as well. For a dollar or so you can get enough piano wire to make lots of springs. For what its wotrh. Brian

doug8082a · Post by **doug8082a** » Fri Jan 05, 2007 1:23 am

The spring mentioned on the 120-140 sight is different than the one in the 170s... at least the 170Bs (never looked at the 170 or A IPC to compare). The spring in the 170b, anyway, has a 90deg bend in it that the 120-140 spring does not.

Here are the pics from Joe Moilanen:

Post by **GAHorn** » Fri Jan 05, 2007 2:20 am

Don't lose sight of the overall picture. Does it make sense to get rid of a great 4-place airplane over a $25 spring that fails every 50 years, to buy a mediocre 2-place "modern" airplane that doesn't have the same abilities or appeal that will charge $25 for a door-hinge that fails regularly?
Keep a cool head about such things.

wa4jr · Post by **wa4jr** » Sat Jan 06, 2007 11:34 pm

The cloud has moved off and I'm OK now....that I sat down a couple of nights ago with some fine Port Wine

That sure is a nice latch assembly. The new springs are quite a bit heavier that the little fiddly things that go around the handle hinge pin as per original. I may just hold the original springs in stock and try to fit a pair of heavier coil tension springs. I can't see the spring that activates the latch, however. Is it in there somewhere? Is it the original. Since mine were gone, I have no idea how the new ones install and hope that it will be evindent when I have the shiny gold originals in my hand

wa4jr · Post by **wa4jr** » Wed Jan 10, 2007 6:16 pm

My springs have arrived, and it appears the door latch spring, #0411554 is of a new and improved design. I've never seen the original, but this new spring is not a single piece of flat spring steel. It is a dual coil spring similar to the one that goes on the handle, but much beefier. Somehow this new spring looks as if it is installed around the hinge pin on the latch cam, and puts a lot of outward force on the cam, thus insuring a positive door closure.

The picutures posted earlier have two coil springs that seem to pull the handle in while forcing the latch cam out...doing away with the dedicated latch cam spring. This would certainly work, for much less green, but I'll go ahead and install the factory parts and see what happens

wa4jr · Post by **wa4jr** » Wed Apr 18, 2007 1:22 pm

The job has been complete for some time now, but just now having time to write. The complete rebuild, cleaning, and new spring installation on the left door latch has worked wonders. Was a a bit difficult to install the new springs correctly, as the old ones were in pieces and the manual didn't say squat, but all worked out OK. I did make it a point NOT to rivet any of the latch assembly into the door. I used pan-head machine and steet metal screws so that when the springs decide to break again, I don't have to drill out rivets

lowNslow · Post by **lowNslow** » Wed Apr 18, 2007 3:43 pm

wa4jr wrote:I used pan-head machine and steet metal screws so that when the springs decide to break again, I don't have to drill out rivets

Mine were modified at some point by using rivnuts. They were installed in the two empty holes shown in the pictures below (where the rivets would go). Really made it easy to remove when I had to replace the springs.

mongo2 · Post by **mongo2** » Sun Sep 05, 2010 9:30 pm

I'm in the process of final re-assembly of my doors. Could someone post a picture of the door post and striker plate, as well as a picture of the door with the phenolic "half-moon" shown? I'm looking at the IPC , but I am slightly confused as to how the flat on the door latch is orientated to hold the door shut on the striker? I know the door latch can only be assembled in one position, but I'm having a hard time "seeing" this. My aircraft is far from where I am, so I have nothing to reference other than the door.

Any help appreciated,

Rick

Post by **GAHorn** » Mon Sep 06, 2010 6:26 pm

I'm going to post some pics that may/may not be found helpful. The first set of pics is a modification to the original mouse-trap spring, using common hardware-store tension springs. Click on the pics to englarge them.
I do not think this mod will make your airplane unairworthy or cause it to fall out of the sky.

cessna170bdriver · Post by **cessna170bdriver** » Tue Sep 07, 2010 3:45 pm

mongo2 wrote:I'm in the process of final re-assembly of my doors. Could someone post a picture of the door post and striker plate, as well as a picture of the door with the phenolic "half-moon" shown? I'm looking at the IPC , but I am slightly confused as to how the flat on the door latch is orientated to hold the door shut on the striker? I know the door latch can only be assembled in one position, but I'm having a hard time "seeing" this. My aircraft is far from where I am, so I have nothing to reference other than the door.

Any help appreciated,

Rick

I'm confused too. Even looking at it and watching it work, it still seems backward, but works very well.

Here's a few photos of the left door latch and striker of my '55 B-model, sn/26541.

mongo2 · Post by **mongo2** » Thu Sep 09, 2010 12:15 pm

Well ,now at least I don't feel as alone as not "seeing" how this latch works. It did seem to be backwards to me as well, thus the question. Thanks to you and George , I know I have things in place correctly. I took the the latch to the airport yesterday, and was able to see it work against the door jamb\striker. It does seem though that most latches would end up with the flat against the striker, but not in this case. I can now complete the riveting on the new door skin. I also changed my latch springs to the way George has his, and I installed rivnuts in the door jamb, and used nut plates on the latch. It is all completely removable.
Thanks again!

Post by **GAHorn** » Fri Sep 10, 2010 6:03 am

mongo2 wrote:.... I also changed my latch springs to the way George has his, ...

Just to be accurate....those pics are not of mine. (I have original 172 rotary latches in my 170.)

The International Cessna 170 Association

Door Catch and Door Handle Latch repairs

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