The International Cessna^® 170 Association

My door latch is significantly worn on my 56 170b, and my door pops open at every hint of turbulence and on all landings.

The handle mechanism still works well, but the bolt/latch is worn. The strike plate looks fine.

Is there a replacement part available to swap out the worn bolt/latch, or do I have to replace the entire assembly?

Alternatively, I was considering filling the concave portion with JB Weld, then sanding/filing it down to be smooth and fit.

Reese. most of the time a door opening is an indicator that that spring that is suppose to keep the latch out holding the door closed, is broken. Despite you taking a very nice close photo of the latch, I can't see a spring at all on your latch which is somewhat unusual unless the spring has completely broken away. Usually there are remnants of the broken spring.

So look close, there should be a spring on the shaft the latch pivots on and it should be pushing the latch out. Of course most of the original springs have long broken and many have used other springs cobbled into the latch to make them work at all. Cessna actually went to this system.

I make replacement and sell latch springs like the original. They are commonly called mouse trap springs. I've been told and have seen myself the new mouse trap springs themselves or used in conjunction with other cobbled springs, make the latches work well, many have said like new.

So look very closely at your latch. Look for a spring that should be holding it out. I doubt very much that the wear on the latch you show in your picture is what is causing your door to open.

I should have added, if you find the latch is under some spring load to stay out and you want to try something to make the latch work better. Try shimming out the door strike a little with a thin washer or two. If is very common to see door strikes shimmed out from the fuselage to engage the latch better.

Bruce Fenstermacher wrote:Reese. most of the time a door opening is an indicator that that spring that is suppose to keep the latch out holding the door closed, is broken. Despite you taking a very nice close photo of the latch, I can't see a spring at all on your latch which is somewhat unusual unless the spring has completely broken away. Usually there are remnants of the broken spring.

So look close, there should be a spring on the shaft the latch pivots on and it should be pushing the latch out. Of course most of the original springs have long broken and many have used other springs cobbled into the latch to make them work at all. Cessna actually went to this system.

I make replacement and sell latch springs like the original. They are commonly called mouse trap springs. I've been told and have seen myself the new mouse trap springs themselves or used in conjunction with other cobbled springs, make the latches work well, many have said like new.

So look very closely at your latch. Look for a spring that should be holding it out. I doubt very much that the wear on the latch you show in your picture is what is causing your door to open.

Thanks for this. There is tension against the latch, although not much. I can feel a spring in there, but it feels like it's quite worn. I'll send you a message to order some new springs, as I'll likely need them regardless of the door issue.

I'll also try shimming the door strike out a bit too and see if that helps.

Unless someone has added springs to the inside of the latch mechanism the only spring that actually is in the mechanism can be seen in this sample of my latch. As you have a '56 your outside door handles will also have springs but all they do is hold the outside door handle closed. Can you see a spring like the one the arrows are pointing to? This is what the springs, one each latch look like.