Gear Warning System Animation

[John DeRosa OHM Ω http://aviation.derosaweb.net]

I got an email from a glider pilot wanting to install a gear warning system in his ship. While the system is electrically simple (battery+wires+switches) it can be logistically complicated.

I started to reply via email to convey the needed information but this just doesn't work. So I spent some time putting together a PowerPoint presentation covering what I know about gear warning systems. It includes a PowerPoint animation of how the gear warning functions mechanically and electrically.

This is a second public release of this DRAFT presentation. I'd like your feedback. Let me know if you have any questions or confusions so I can make needed updates.

You will need Microsoft PowerPoint to open the file and then "play" the presentation and its animation.

http://derosaweb.net/aviation/presentations/documents/Landing_Gear_Warning_2022.07.15.pptx

Is there a way to export the slide show (and animation) to something more portable? You can save-as to a MP4 file but it runs through the animation too fast to understand (but you can use the space bar to stop/start). Can it be opened and run properly in Open Office or Google Docs? I haven't tried.

Thanks, John (OHM)

[Dan Marotta]

Nice job, John.

But, since I don't use Microsoft products and the Open Office animation
was not as good as it could have been, I'm not sure about your switch
mounting.

It appears to me that you mounted the gear switch on the landing gear
itself. I would suggest that it would be much simpler to mount it on
the linkage in the cockpit. Saves wallowing in the dirt to install and
less chance of the switch getting knocked off in the cockpit.

Dan
5J

[John DeRosa OHM Ω http://aviation.derosaweb.net]

On Saturday, July 16, 2022 at 10:36:30 AM UTC-5, Dan Marotta wrote:
> Nice job, John.
>
> But, since I don't use Microsoft products and the Open Office animation
> was not as good as it could have been, I'm not sure about your switch
> mounting.
>
> It appears to me that you mounted the gear switch on the landing gear
> itself. I would suggest that it would be much simpler to mount it on
> the linkage in the cockpit. Saves wallowing in the dirt to install and
> less chance of the switch getting knocked off in the cockpit.
>
> Dan
> 5J

Dan - Yes, the best place is on the linkages.

I use the term "linkages" throughout the narrative and mention a suggested location near the gear and airbrake handles.

Thanks, John (OHM)

[quietpilot]

The presentation labels the switches on the levers/contols on the PPT I saw.

I exported to google slides and the animations can't be made work quite right. The animation options are not as sohisticated to start and stop at specific positions.

Jim M "P9"

[John DeRosa OHM Ω http://aviation.derosaweb.net]

> I exported to google slides and the animations can't be made work quite right. The animation options are not as sophisticated to start and stop at specific positions.
>
> Jim M "P9"
The closest that I have found is exporting within PowerPoint to an MP4.

I have added a link on my presentations web site (http://aviation.derosaweb.net/presentations/#gearwarning) to the MP4 file with an explanation and instructions.

[krasw]

I have struggled with magnetic switches for years. Attaching them to gear/airbrake pushrods seems easy, but the tolerance between magnet and switch is very small making installation easily unreliable. Last time I did gear warning system I used microswitches and everything works 100%. I would not bother with magnet switches anymore.

[Mark Mocho]

On Thursday, July 28, 2022 at 5:29:58 AM UTC-6, krasw wrote:
> I have struggled with magnetic switches for years. Attaching them to gear/airbrake pushrods seems easy, but the tolerance between magnet and switch is very small making installation easily unreliable. Last time I did gear warning system I used microswitches and everything works 100%. I would not bother with magnet switches anymore.

I too detest magnetic switches. Unless they are mechanically fixed in place with screws or clamping devices, the tape will not hold in a hot environment. If the switch moves out of the intended position even a small amount, the alarm either triggers or worse, is disabled and you don't know it. Use microswitches and clamp them firmly in place. Test the circuit on the ground repeatedly. After reinstalling the seat pan or any other panel that covers the switches and actuating rod/lug/tab, test again. Finally, test it in flight. Repeat the inflight test occasionally to make sure everything is operating normally.

Finally, consider something other than a warning horn. Many of these inexpensive (cheap) buzzers have a tone that is difficult to hear in the cockpit while in flight. Additionally, the pitch sometimes coincides with hearing loss in a particular frequency range. (Fairly common in people who spent time around loud airplanes, firearms and other noisy environments. Many of our flight instruments like audio variometers, radios and anything else that makes noise might be enough to mask the buzzer. A pilot in a stressful situation like an outlanding may just ignore another beep, honk or tweet. I changed my gear warning to a set of red/blue flashing LED lights in the panel. They hook up just like a buzzer would and only need a couple of 3/16 holes in the panel. Since I don't have ANY other lights in the cockpit, there is no mistaking what is going on. Oh, and I installed a test switch to check whether they are working. And, yes, I did have a gear up landing once. But not with this system.

[Dan Marotta]

What Mark said.

One can easily source the parts and build a warning system or simply buy
a ready made kit from, say, Wings and Wheels. Their kit does not have a
flashing light, but it would be easy to insert one or more flashing LED
lights in parallel with the horn.

Dan
5J

[Dave Nadler]

On 7/28/2022 7:29 AM, krasw wrote:
> I have struggled with magnetic switches for years. Attaching them to gear/airbrake pushrods seems easy, but the tolerance between magnet and switch is very small making installation easily unreliable. Last time I did gear warning system I used microswitches and everything works 100%. I would not bother with magnet switches anymore.

You may want to watch this discussion of switch problems:
https://youtu.be/R--m0NDR0j8?t=339
Plenty of ways to get something unreliable...

[John DeRosa OHM Ω http://aviation.derosaweb.net]

Mark,

I have to respectfully disagree with your opinion of magnetic (reed) switches versus mechanical micro-switches. I started installing gear warning systems in gliders by using micro-switches and quickly converted to the use of magnetic switches.

A few comments.

- I agree that the check buzzers are trash and should not be used. If you want a robust warning horn that will wake up the dead use the Sonalert brand (SC series). W&W's has that in their kit.
- I have seen too many examples (in gliders and otherwise) of lever activated micro-switches being bent, broken and/or destroyed. If a standard magnet isn't strong enough, use a rare earth one instead.
- Micro-switches requires a particular mounting arrangement where the activation "arm" must push on the lever from a specific direction. A magnetic switch allows for activation in a variety of orientations.
- I have often see micro-switches with elongated holes for the screws. Elongated holes are a recipe for movement caused by vibration.
- I suggested in my presentation of mounting the magnetic switch and magnet with tape but only during the trial fitting. I suggest, and use, a good brand of epoxy to permanently mount the magnetic switch and the magnet. West Systems is very good.
- Relying solely on warning lights to tell you of an impending gear up landing just doesn't seem right and can easily be not noticed, especially in a brightly lit cockpit. Airliners don't rely only on a warning light if important things aren't correct - why should we?

I do need to add another slide talking about adding a test switch. But I prefer testing after rigging by having the gear up and the brakes out!

The latest version of the presentation can be found at http://aviation.derosaweb.net/presentations/#gearwarning.

Thanks, John (OHM)

[Mark Mocho]

John-

To each his own. My experience with magnetic vs. microswitches is exactly the opposite, and I have installed about ten gear warning systems using both. Maybe I'm doing it differently and getting different results than you, but I've had better results with microswitches.

As far as the lights, I GUARANTEE you can't ignore the ones I am using. You could probably see them if you were wearing a welding hood.

[2G]

Not mentioned here are Hall-effect proximity sensors. They have an excellent detectability range and are very reliable because they are solid-state.
https://www.amazon.com/Twidec-Proximity-Inductive-NO%EF%BC%88Normally-NJK-5002C/dp/B07P1GKQRM

Note: I have never had to depend upon a gear warning system. My landing checklist is pretty simple: touch every control and the radio to be sure it is in the landing position prior to entering the pattern. I also have a written checklist in the LXNAV.

Tom

[John DeRosa OHM Ω http://aviation.derosaweb.net]

Tom - A Hall Effect (HE) Sensor can be a good substitute for a reed switch but;

- The HE is slightly more complicated to wire as it is an active device requiring power to work while the reed switch is strictly a mechanical device.
- Physically mounting some of the most common, and larger, types such as the one you link to may not work in our tight environments.

But I did add a slide about Hall Effect Sensors at the end of the deck.

- John (OHM)