Door Locking Mechanism

punkin170b · Post by **punkin170b** » Fri Jul 02, 2004 10:28 pm

We're wondering if anyone has changed out either 1.) the door latch mechanisms in the early 170B to be a more positive lock like the later Cessnas - specifically late 60s early 70s style; OR 2.) changed out the entire door assemblies and had it approved. Were there any pitfalls or considerations to ponder before undertaking this project? Any other options out there?

We would like to do this for security reasons and to keep the door positively closed in flight and in motion on the ground with really young kids in the back seats...

Again, Thanks!

Matt

zero.one.victor · Post by **zero.one.victor** » Sat Jul 03, 2004 3:47 am

I seem to recall that someone (John D Benham?) has an approval and/or a kit to install the later rotary-type latches in the 170.

Eric

Post by **GAHorn** » Sat Jul 03, 2004 8:32 am

Several 170's have the later 172 "rotary" latches, including my own, and they work much better than the originals but how secure is any airplane on the ramp with plastic windows that open with a knife blade?
The best reason to convert to the rotary type in my opinion is parts availability and a smoother, more dependable latching mechanism. This is a minor modification and requires only a logbook entry (See FAR 1.1 for def'ns of major alterations/repairs) and a little scrounging at the junk yards.

zero.one.victor · Post by **zero.one.victor** » Sat Jul 03, 2004 4:29 pm

Matt, upon re-reading your post I notice that one of your objectives is to keep the doors secure with youngsters in the back. I have noticed that the factory ( & most usual) position for the interior door latch is facing aft, where it is easily opened with a downward push--intentional or otherwise. I turned mine to face forward,where they now require an upward pull-- much less likely to occur by accident. They are also less accessible by back-seaters.
I agree with george re: security on the ramp-- regardless of which latches you have, it isn't hard to break into an airplane if you don't mind doing a little damage. I think that turning the interior handles around might meet your need to prevent back-seaters from escaping. And it's a lot cheaper ( read free) than new latches or new doors.

Eric

punkin170b · Post by **punkin170b** » Sun Jul 04, 2004 2:35 am

Hey guys, thanks for the input. I agree that the security issue is somewhat moot - as with any security device: if great enough, the intent of the perp will always defeat any mechanical or automated security measure. On a couple occasions I have personally bypassed the locks on my own airplane without inflicting any physical damage when I needed access and was boneheaded enough not to have my key on hand. This made me think about insurance companies and the need to prove forced entry if somebody decided they wanted my goodies.

The other issue - safety - is actually the most important. I have already reversed the door handles as suggested. My golden retriever inadvertently opened the passenger door while I was in motion on the ground once. My mind got to whirling (pardon the pun) about propeller blades and other airplanes and such. I reversed the handles before we took our dogs on a trip again. Airborne, this would not be a problem. With all your strength, the slipstream prevents you from opening the door more than 3-4 inches - keeping your loved ones from going skydiving - but also making it almost impossible to resecure the door if it pops open in flight. It is very annoying to continue a flight for a couple hours with the door ajar.

Positive locking mechanisms would alleviate these worries... Thanks again for the help, fellas...

Matt

zero.one.victor · Post by **zero.one.victor** » Sun Jul 04, 2004 5:35 am

zero.one.victor wrote:I seem to recall that someone (John D Benham?) has an approval and/or a kit to install the later rotary-type latches in the 170.

Eric

I just looked thru my old Flypapers--back in December 2002 John D Benham advertised "rotary door latch kit, $400." His contact info's in the Assn directory in the Texas listings.

Eric

Post by **GAHorn** » Sun Jul 04, 2004 12:15 pm

Whatever your decision you might wish to consider the adviseability of locking your cabin doors before take-off.....
....IN THE EVENT of a take-off accident a locked door is an impediment to rescuers who may not be able to remove you quickly from the wreckage. I never lock my doors for flight.
(And another reason the rotary latches are better in my opinion is that it is rare they ever inadvertently are opened in flight. Rotary latches are simply a better design. I think I'd find my own parts to do it though at the prices some people want for them.)

punkin170b · Post by **punkin170b** » Sun Jul 04, 2004 3:05 pm

I guess I should have been more clear instead of so liberal with the use of the term "locking mechanism". The rotary latch is exactly what I want to do. I never "lock" the doors in flight either, George. (Although 1/8 or 3/16 plexi is alot easier to penetrate than the 3/4 inch thick multi layered stuff at work! Did you ever see the picture of the hole they pulled the FO through in that ASA Brasilia crash back in '95? eek.)

Thanks for all the input, guys.

Matt