The International Cessna 170 Association

Hello, My door latches are inop. I have read the problem is a spring in an inconvenient area to repair. Just hoping a more resourceful solution has come to be?? If not will you direct me to "how to" article? Thank you kindly! Tim

Do a search for "mouse trap" and you will hit on several threads discussing this problem and hint as to the repair. There is no tutorial step by step written to follow.

Click to search -> http://www.cessna170.org/forums/search. ... Mouse+trap

In these links you will learn the so called mouse trap spring you will need is not available from traditional sources. You will also learn of a Cessna spring kit that supersedes the mouse trap spring. And you will learn of alternate springs that might be used that you could find locally for much less than the Cessna going rate for like springs.

If you want mouse trap springs, I can make, probably provide them in a week or so. I simply have to install them in my airplane first to confirm they are serviceable.

I recall there used to be a guy in the C120/140 group that would make mousetrap springs too. I bought a pair from him probably 7-8 years ago. His contact info is probably buried deep someplace here on the forum also.

rydfly wrote:I recall there used to be a guy in the C120/140 group that would make mousetrap springs too. I bought a pair from him probably 7-8 years ago. His contact info is probably buried deep someplace here on the forum also.

https://www.cessna120-140.org/Classified/springs.htm

Here's a simple and inexpensive method (click on pic to ENLARGE) :

gahorn wrote:Here's a simple and inexpensive method (click on pic to ENLARGE) :

And they're still working George! Ace Aviation Hardware Store...

Joe

So what am I reading.

Two simple springs from McMaster Carr and no need for the original mouse trap spring.

Is it that easy.?

Yes to the ACE Hardware springs, however, it is not that easy to remove and reinstall the catch. It takes your best McGyver impression to deal with these latch mechanisms. Of course once you've done it 5 or six times you might scoff at the task. This because you've already drilled all the necessary rivets, have confidence there really is nothing else holding the latch in the door and you've engineered the rivet replacement screws and Tinnermans. You've become a master at removing the door handle, and can find and remove all the screws that hold your door upholstery on. And lets not forget you've already modified your door seal that blocks the removal of the mechanism from the door.

Over the week end, for fun I removed both my doors. I removed one latch and experimented with the best way to install a new mouse trap spring. While I was at it I perfected the mouse trap spring I can produce. I've had the latch in and out of my door 4 times to include major disassembly of the latch mech., something I not recommend anyone do with first taking and confirming you have 30-40 good clear photographs of this puzzle from every angle. I was taking lots of pictures to use for a how-to article on the subject, and I didn't take enough. I had to look at the other latch to figure how that thing went back together when it fell apart in my hand.

I also realized that likely there are no two exact duplicate door latch mechanisms today due to repair schemes necessary. My latches included. This is not a task for the casual McGyver. You could easily get into this and make the whole assembly worse with even more repair or parts sourcing necessary.

However I can say I'm very pleased with the finished result of the latch I repaired with a new mouse trap spring. The latch mechanism had long ago had ACE hardware type springs installed and I left them there to help (backup) the new mouse trap spring.

Perhaps this might help... from the C172 IPC:

MoonlightVFR wrote:So what am I reading.

Two simple springs from McMaster Carr and no need for the original mouse trap spring.

Is it that easy.?

Those are mine pictured, did this several years ago and still working.

Joe

Thank you so much for your posts. This little mechanism has always seemed incredibly complicated to have such a simple function.

Todd
(new member this month!)

Welcome!

Let me make sure I have it.

All of the discussion has been about replacing PN 0511119, Spring-Door Handle Return. Right?

There is another spring in there, PN 0411554 Spring-Door Latch. It appears to my mind that this spring isn't actually needed to close the latch because the pressure is provided by the connecting rod (pull bar) that goes through to the catch from the pin that is on a pivot bracket. Right?

From George's excellent photos, it seems the two spacers on the moving pin have been removed. Correct?

Finally, to install the springs a small hole needs to be drilled on each side of then Door Latch Housing PN 0511112-2. Right.

ravenaviation wrote:Let me make sure I have it.

All of the discussion has been about replacing PN 0511119, Spring-Door Handle Return. Right?

There is another spring in there, PN 0411554 Spring-Door Latch. It appears to my mind that this spring isn't actually needed to close the latch because the pressure is provided by the connecting rod (pull bar) that goes through to the catch from the pin that is on a pivot bracket. Right?

From George's excellent photos, it seems the two spacers on the moving pin have been removed. Correct?

Finally, to install the springs a small hole needs to be drilled on each side of then Door Latch Housing PN 0511112-2. Right.

Complete door latch/handle spring modification instructions (SK 172-16C 2 which is made applicable to the C-170 via SL 63-17) are found in the MX Library: viewtopic.php?f=36&t=9689

I gotta get one of these, although I think I will buy the springs from Bruce. The service kit SK172-16C is available from Cessna current price $143.64, 1963 price $1.02 that's an increase of 13982.352941176467%.
Regards,
Jim