Rear seat stops

[Utah20Gflyer]

Hello Mooney community!  I didn't really like the home made rear seat stops that came with the plane when I purchased it and the weather sucked today so I decided to start another project.    The originals were made from some aluminum extrusion and then were tapped for a thumb screw to tighten it down.  They didn't fit too well and tended to pop off regularly.  It was difficult to get them tightened down without a tool but it was difficult to get a tool where I needed it to do the job. 

 I 3d printed these as replacements.  The small one in the back of the picture is version 1.  It worked pretty good but I could get it to pop off by repeatedly slamming the seat into it like a passenger might.  The two longer ones are V2, I'm hoping they will have greater staying power.  I'll post a picture of them installed tomorrow if I get a chance to get out to the airport. 

[Prior owner]

That’s amazing work you’ve done with a printer!

I do question the idea of putting any kind of clamp on the seat rail though- I have only ever seen a chubby cotter pin, clevis pin, or screw/bolt in the rails for stops. They are designed to positively stop the seat from sliding too far forward during impact…..a clamp type block would not provide the same level of safety.

or are you using these in addition to the factory stops? Also, Clamping the aluminum rail with set screws may damage it-remember that it is the only thing holding the seat to the floor.

Maybe I’m not seeing how these fasten in place though- perhaps a pic of them installed would help?

 

[A64Pilot]

It’s a Cessna thing, several people in Cessna’s have been killed when at rotation their seat slides full travel to the rear and of course they only have the yoke to hold onto, so zoom climb, stall.

Some of the better cures for Cessna’s have been a type of inertia reel that won’t release until the handle is pulled up so if the pin comes out of the rail the seat still won’t move aft. But there are lots of rail stops to limit rearward travel too, the good ones in my opinion have a spring loaded vertical pin that drops into the hole just like the seat does, so all you have to do is pull the ring and slide the stop where you want it, but apparently seat stops aren’t needed in Mooney’s for some reason they don’t come loose. My theory is because a Cessna seat is tall, high up from the floor, while a Mooney’s seat is on the floor, perhaps being high up has more leverage to pull the pin out?

Our stops aren’t safety stops, they merely keep the seats from coming off of the rail if they are moved full aft or rearward, which of course we need to do to remove them.

These or a copy of them may be what he had

https://www.aircraftspruce.com/catalog/pspages/saftstop.php?clickkey=3375886

Edited March 6, 2022 by A64Pilot

[Utah20Gflyer]

3 hours ago, PilotCoyote said:

That’s amazing work you’ve done with a printer!

I do question the idea of putting any kind of clamp on the seat rail though- I have only ever seen a chubby cotter pin, clevis pin, or screw/bolt in the rails for stops. They are designed to positively stop the seat from sliding too far forward during impact…..a clamp type block would not provide the same level of safety.

or are you using these in addition to the factory stops? Also, Clamping the aluminum rail with set screws may damage it-remember that it is the only thing holding the seat to the floor.

Maybe I’m not seeing how these fasten in place though- perhaps a pic of them installed would help?

 

There are holes in the front of the seat rails to prevent the seat from traveling too far forward but there doesn't seem to be anything on the rear of the rail.  I'll take one last look later today but I hadn't seen anything.  The only solution I can see is to have something clamp on.  

On the front of the rail the original mooney solution is actually a cotter pin.  I bought some but ended up using #4 machine screws which fit nicely through the hole and are easier to install and remove.  

I've made sure to use set screws with flat tips and the plastic has some flex to it which should help minimize and wear to the rail.  

Is anyone else using seat stops on the rear of the rail?  If so what have you used?  I've had passengers run the seat to far back and then had some difficulty getting the seat lined up again so it will go forward again.  

[Ragsf15e]

37 minutes ago, Utah20Gflyer said:

There are holes in the front of the seat rails to prevent the seat from traveling too far forward but there doesn't seem to be anything on the rear of the rail.  I'll take one last look later today but I hadn't seen anything.  The only solution I can see is to have something clamp on.  

On the front of the rail the original mooney solution is actually a cotter pin.  I bought some but ended up using #4 machine screws which fit nicely through the hole and are easier to install and remove.  

I've made sure to use set screws with flat tips and the plastic has some flex to it which should help minimize and wear to the rail.  

Is anyone else using seat stops on the rear of the rail?  If so what have you used?  I've had passengers run the seat to far back and then had some difficulty getting the seat lined up again so it will go forward again.  

Interesting, my rails have a hole through the back as well for a cotter pin to stop the seat.  Mine is on the rail closest to the trim wheel.

[Utah20Gflyer]

1 hour ago, Ragsf15e said:

Interesting, my rails have a hole through the back as well for a cotter pin to stop the seat.  Mine is on the rail closest to the trim wheel.

I checked both inner and outer rails and couldn't see anything.  Here is what they look like installed.  

[kortopates]

39 minutes ago, Utah20Gflyer said:

I checked both inner and outer rails and couldn't see anything.  Here is what they look like installed.  

The picture is of the outer rail, so the other inner rails will have holes for large cotter pins at the very front and very rear right where your device is. Are you saying yours didn't have the cotter pins installed? Of course they get removed at every annual and are normally replaced when the seats go back in. 

Re-reading the thread, I see you mentioned you did find the holes at the front but not the rear and the machine screw is popuar alternative to the cotter pin. But you should really find the same holes in the rear right where the rail narrow, like where you device is. If you have an IPC you can confirm but to my knowledge this is unversal to all Mooney seat rails.

Edited March 6, 2022 by kortopates

[A64Pilot]

The holes aren’t as far back as you would expect, they are about level with the back of the emergency gear extension “thing” (J model)

Sorry about the picture it’s the best I can do without dragging a drop light over. The holes are hard enough for me to find that I draw a line with a sharpie right on-the top of the rail where they are. As noted, they are on the inner rails only.

Perhaps since our seats can’t go as far back as a Cessna is why there is not an AD on a Mooney?

 

Edited March 6, 2022 by A64Pilot

[PT20J]

Cessna had a lot of seat slippages due to wear of the holes and shallow pin engagement. The Mooney rails are beefier. On Mooneys, the stops keep the seats from sliding off the ends of the rails as @A64Pilot said and additionally the rear stop keeps the front seats from sliding back (Mooney points uphill sitting on the ground) and crushing backseater’s legs. 

Mooney used to use cotter pins. Later switched to screws, nuts and a couple of standoffs. I made mine simpler by switching to threaded standoffs and eliminating the nut.

Skip

[Rjfanjet]

My mechanic didn't like the cotter  pin in back, so we fabricated a stop with a clevis pin and a small bracket similar to the Cessna stops.

[Utah20Gflyer]

2 hours ago, A64Pilot said:

The holes aren’t as far back as you would expect, they are about level with the back of the emergency gear extension “thing” (J model)

Sorry about the picture it’s the best I can do without dragging a drop light over. The holes are hard enough for me to find that I draw a line with a sharpie right on-the top of the rail where they are. As noted, they are on the inner rails only.

Perhaps since our seats can’t go as far back as a Cessna is why there is not an AD on a Mooney?

 

I need to check again, I wasn't expecting the hole to be that far forward.  Could be that's why I missed it.  Thanks!

[M20F-1968]

I have a set of the Cessna seat stops which I machined to fit the Mooney seat rails.

These are the items in the Aircraft Spruce Catalog:

https://www.aircraftspruce.com/catalog/pspages/saftstop.php?clickkey=3375886

I have one each on the inboard seat rail.  They can be easily slid against the seat and tightened while sitting.  

I can post pictures when I get to the hangar.

The alterations that were needed was to widen the opening to allow the full thickness of the vertical (stem of the "T") of the seat rail to fit.  The remained of the extrusion needed no further alteration.  They were worth the cost and labor to make them fit.

John Breda