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The Seatbelt Saga - Shoulder Harness Edition


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After reading through several of the posts on here on installing Shoulder Harnesses on an older short-body Mooney, I figured I'd give back to the community with our process on installing inertial reel shoulder harnesses on our 1965 Mooney M20E. 

Resources/Reference Threads

 

Which kit we installed, and what to know before you order?

We installed the inertial reel shoulder harnesses with lift-lever buckle release from Alpha Aviation: https://alphaaviation.com/mooney-m20-a-thru-k-front-inertial-reel-shoulder-lap-belt-replacement-upgrade-lift-lever-buckle/ . Can't say enough good things about them, they were extremely helpful over the phone and when we lost some of the washers in the included minor change kit (more on that later), they were kind enough to mail me a baggie full at no additional cost. 

Before you order, you need to know 3 things:

  1. What's the attachment point of the seatbelt to the airplane? There are two. Either it is bolted on where a bolt goes through to attach it to the airplane, or it's hooked on, where there's a metal hook clamp at the end of the lap belt that hooks into the metal ring on the seat. 
  2. What colour do you want? Match the interior. We went with the Fawn, they look great!
  3. Push Button or Lift Lever? Personal preference. They say not to use the lift lever with the manual gear, however after a half dozen flights on ours with the Johnson bar I've never had it release on me or cause issues.

Now the fun part - installing!

Tools Needed:

  • Masking Tape
  • Set of wrenches, if I remember correctly, a 9/16ths and a 5/8ths is what we used the most
  • Handy phillips head screwdriver
  • Slack-jaw pliers
  • Needle-nose pliers
  • Socket head wrench for the bolt (or you can do it with a regular wrench)
  • Cotter pins since you're removing the seat
  • Drill with multiple bits (recommended a rotary ream)

 

Overview Video

Step One

Remove the seats. You're going to need the access, and this makes it easier to unhook the old seatbelts anyways. 

Step Two

Pray to Al that the engineers when assembling your particular Mooney gave you a little bit of clearance between the steel bars of the cage and the skin of the aircraft. Okay, now you're ready to get started. Do the pilot's side first, it's by far the hardest, and also the one you're most frequent to use.

Step Three

Remove the side-plastics on the side you're working on, for this guide, I'm going to focus on the Pilot's side as I recommend to do that one first. Remove the window surrounds - side plastics/paneling around the windows. Remove the headliner.

Step Four

Now the fun part. Take the clamp, and open the clamp up by inserting a screwdriver into each hole opposite of each other so they make an X, then push against them to open the clamp up so it will fit over the tube. You're going to need to install the clamp, included with the minor change kit, around the structural tube that runs in between the two windows with the flange & screw holes facing aft. This is murder. It is very hard to get the clamp on and turned around and took us probably 3-4 hours to do it. I wish I had advice for you, but there's not really any. What we did was used the needle nose pliers to hold the aluminum around the tube back and then just brute forced it on and kept pushing/turning, pushing/turning until it was where it needed to be.

One thing that makes it a little easier - try to find the place with the most clearance between the skin of the aircraft and the tube. For us, it was at the top under the headliner. We worked it on there then just shimmied the clamp down.

IMG_2628.thumb.JPG.711937ca08c7b62c00dec87281057f9a.JPG

IMG_2626.thumb.JPG.d111581af16b8b518051db11f3cff397.JPG

 

 

 

 

 

 

 

 

 

 

Step Five

Once you finally have it turned around, align the clamp to the vertical midpoint of the two windows, then use those slack-jaw pliers to tighten the clamp.

IMG_2629.thumb.JPG.74154e0c03ace41c2c46c6f6be9a0d74.JPG

 

 

 

 

 

 

 

 

 

 

Step Six

Now it's time to do a test fit. The minor change kit includes the bolt, washers, spacers, and nut that you'll need. They are going to go through the provided hole on the inertial reel box, then through the two holes on the clamp, affixing the nut on the end of the bolt (spoiler alert: tightening the bolt on to that nut is like doing open heart surgery with swiss army knife tweezers), like so.

IMG_2631.thumb.JPG.cd9be2f4b53a7247783e2322a52523dd.JPG

 

 

 

 

 

 

 

 

 

 

Step Seven

Do a test fit with the bolt through the clamp holes. Is the clamp in the right position or is it too high/too low?

IMG_2633.thumb.JPG.7b183af56ab6642b6d0b83fcf86b4f5c.JPG

 

 

 

 

 

 

 

 

 

 

Step Eight

Take the plastic window surrounds you removed earlier and line it up with the bolt holes on the clamp to determine where you need to drill the hole for the bolt to go through the plastic and into the clamp. It's more of an art than a science and requires some eye-balling. Mask off the hole, then use your drill & rotary ream to drill a hole big enough for the bolt to go through in the plastic window surrounds. 

Step Nine

Make a blood sacrifice to Al. This part took us the longest. You're going to have to put the bolt through the inertial reel box, through the plastic window surrounds, through the bolt holes of the clamp, and hold the nut at the end of the clamp in place while you tighten the bolt on. Congratulations, you've got about an inch and a quarter to work with to hold it in place, and I hope you're instrument rated because you're not going to be able to see anything as the plastic is covering it. We tried several methods to do this, including using masking tape to tape the nut to the wrench itself but no matter how tightly we got it, it never was enough to hold tension for the bolt to start to thread through. Good luck, and may the Mooney gods be with you.

Step Ten

Once that's on, torque it to the appropriate setting (I want to say it was 70 or 90 inch pounds) and put the plastic cover back on the inertial reel.

IMG_2635.thumb.JPG.e49a89f87cdd00055e22fb2f0eeaddee.JPG

 

 

 

 

 

 

 

 

 

 

Step Eleven

Reinstall the headliner, plastics, etc. into place.

Step Twelve

Reinstall the seat, install new cotter pin, and install the lap belt back on to the seat, then do a test fit. Crack open a cold one, sit back and admire your work, and look at your watch as you realize that just took you almost a full day. 

IMG_2637.thumb.JPG.b53dcfa308075fc557fa1d8dfc72bef9.JPGIMG_2957.thumb.JPG.1ed55705e3e3adb92ce97f3cc83b377d.JPG

 

 

 

 

 

 

 

 

 

 

 

I hope you found this helpful, this was not a fun process, but I will say the passenger's side is much easier (a lot more clearance, and you can actually see!) and rest knowing your flying now just became a lot safer. Apologies for the sideways pictures, they are right side up on my computer but inserting rotated... 

Edited by jacenbourne
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Nice write up. Just a suggestion ...if possible get the clamps with welded nut. Makes life much easier. If you ever have to remove the interal reel. Mine are not the the inertial reel shoulder harness but if I am not mistaken ones that I bought from lasar (I think it was lasar) had ms## clamp with the welded nut as part of shoulder harness kit. Not certain but I think the alpha harness is using the same part number.

If I recall correctly the instructions on the lasar kit said that drilling a small locator was as required. I elected not to drill the hole. Minimizes any potential corrosion. Looks like painted yours which is better but you still have dissimilar metals between screw and tubing structure. Just my personal preference.

James '67C

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I recall 7/16" wrench.  But for the no retract.   I did not want that big reel next to my head if I have a rough landing.    another key point was to not use the box end of the wrench holding the nut.    Because you can't get it off and have to do it over.   There are various sticky values of blue masking tape.  A stickier one will do well.  

Using a less sticky take one to hold nuts in a socket with really long extensions just yesterday.

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4 hours ago, jamesm said:

Nice write up. Just a suggestion ...if possible get the clamps with welded nut. Makes life much easier. If you ever have to remove the interal reel. Mine are not the the inertial reel shoulder harness but if I am not mistaken ones that I bought from lasar (I think it was lasar) had ms## clamp with the welded nut as part of shoulder harness kit. Not certain but I think the alpha harness is using the same part number.

If I recall correctly the instructions on the lasar kit said that drilling a small locator was as required. I elected not to drill the hole. Minimizes any potential corrosion. Looks like painted yours which is better but you still have dissimilar metals between screw and tubing structure. Just my personal preference.

James '67C

Thanks! I think you're correct, IIRC the clamp from Alpha Aviation was an MS P/N. Interesting they offer a welded nut version, that certainly would have made things easier! We did not have to drill any holes other than the hole through the window surrounds for the bolt to go through.

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2 hours ago, Whiskey Charlie said:

Thank you for taking time to create this Jason.  Your side panels look great too!  Did Hector at Aero Comfort do that for you?

Thank you! Good eye, the entire interior is from Aero Comfort. They do fantastic work!

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9 hours ago, PilotCoyote said:

+1 regarding the clamp with welded nut. But where can you get them?

Seems like you could just use a spot of epoxy to hold the nut in place.

I did it the 'hard way' with painters blue tape and an open-end wrench; really wasn't that hard.Or, maybe it just seemed easy after what a TOTAL PAIN IN THE ASS putting the clamp around the frame tube was!!  Gawd, that was two years ago and the memories still haunt me....makes safety wiring a prop look easy!

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+1 regarding the clamp with welded nut. But where can you get them?

I am running off my memory .... It was MS clamp to which the part number I don't recall , It looked someone took the MS clamp tack welded the nut on to the MS clamp.

The weld was done in nice fashion. I  supposed  one could  get an MS clamp and if you are not a welder  or don't have the equipment, take it to your local muffler shop and have them weld a nut on. Of course if you already have the clamp  installed (especially on the left side) I am guessing you wouldn't want go through the hard ache again on opening up the clamp to get it around tubing. .

James '67C

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  • 3 years later...
On 10/25/2019 at 10:44 PM, N201MKTurbo said:

The company I work for just got a $M contract to build a machine to make the hooks for AmSafe!

putting a lot of Chinese out of work!

I hope they have a long contract then.

Not saying Amsafe will, but one of Boeings tricks was to award a lucrative contract, company would spend much money buying new equipment and maybe hire a few extra folks to fill the orders, next year Boeing would offer to pay half and let you know if you didn’t take it they were gone. You took it because you had to, payments on the machines you bought came due every month and without the Boeing contract, you didn't have work enough for the people or machines.

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On 11/27/2022 at 2:12 PM, Born2Fly said:

Hello TheAv8r,

Nice review indeed! Unfortunately the video is no longer accessible. Do you have it on youtube by any chance? Or could you repost it? 

Appreciate it very much. 

You just missed him….  @TheAv8r he was just here…

Unfortunately, storing data costs too much some days….   :)

Best regards,

-a-

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On 11/27/2022 at 1:12 PM, Born2Fly said:

Hello TheAv8r,

Nice review indeed! Unfortunately the video is no longer accessible. Do you have it on youtube by any chance? Or could you repost it? 

Appreciate it very much. 

I had to take it down because it was using too much space on Mooneyspace. The video kind of just reinforces what the pictures are saying though, you're not missing anything between the two :)

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I have shoulder harnesses, but I put them when the airplane  was completely apart and access was quite easy.  The  harnesses are used were from an Ovation  in the required reels are bolted into a steel plate which is welded to the structural cage.   For those of you that know welding,  is there type  welding that can be done  so as to attach the steel plate to a  completed airframe with the interior removed without damaging the nearby external skins.

 Welding the mounting plate  to the structural cage and having the retract reels near the floor seems to be a much better  configuration,  but very few owners  have the opportunity to install shoulder harnesses with the airframe completely disassembled.

John Breda

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7 hours ago, M20F-1968 said:

I have shoulder harnesses, but I put them when the airplane  was completely apart and access was quite easy.  The  harnesses are used were from an Ovation  in the required reels are bolted into a steel plate which is welded to the structural cage.   For those of you that know welding,  is there type  welding that can be done  so as to attach the steel plate to a  completed airframe with the interior removed without damaging the nearby external skins.

 Welding the mounting plate  to the structural cage and having the retract reels near the floor seems to be a much better  configuration,  but very few owners  have the opportunity to install shoulder harnesses with the airframe completely disassembled.

John Breda

You could easily hire a Welder to attach a steel plate to the structural frame without damage to the aluminum skins, then get your IA to sign off on a 337. I would use MIG but TIG would also be fine. Its about a 5 min job, prob less then $50 bucks for both sides, although you may pay a fee for a mobile welder to travel to your hanger. 

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On 11/30/2022 at 5:10 PM, carusoam said:

You just missed him….  @TheAv8r he was just here…

Unfortunately, storing data costs too much some days….   :)

Best regards,

-a-

I managed to install the kit today. After removing interior panels, the installation on the left side took me about 2 hours to get the ring in place. Right side was super easy, no brainer. Had to remove few screws from the windows on the left side to avoid extra pressure on glass. Used a rounded end of the hammer as a wide pry bar to gently depress the cage frame from the skin. Two flat screw drivers to give an initial way for the pry bar. 

Will setup the interior panels after I find the replacement screws (the original screws are not looking good and some were missing or too small).

  • Alpha Aviation 2 seat kit. 
  • Seatbelts - Hooker Harness.
  • 1967 M20F Executive

 

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22 hours ago, Born2Fly said:

I managed to install the kit today. After removing interior panels, the installation on the left side took me about 2 hours to get the ring in place. Right side was super easy, no brainer. Had to remove few screws from the windows on the left side to avoid extra pressure on glass. Used a rounded end of the hammer as a wide pry bar to gently depress the cage frame from the skin. Two flat screw drivers to give an initial way for the pry bar. 

Will setup the interior panels after I find the replacement screws (the original screws are not looking good and some were missing or too small).

  • Alpha Aviation 2 seat kit. 
  • Seatbelts - Hooker Harness.
  • 1967 M20F Executive

 

I'm impressed!  Took me about 4 hours of cursing to get the pilot's side clamp installed.  I did the passenger side first and thought no big deal...I'll be done in no time.  HAH!

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On 10/24/2019 at 10:02 PM, carusoam said:

Nice details, Jasen!

Thanks for sharing them.

Super fancy finished interior too!

Anyone still not have shoulder harnesses?

Best regards,

-a-

I don’t.  Been wanting it do it for years.  After reading the thread, I’m not sure I’m ready for another fight.  TBD.  

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On 12/5/2022 at 11:49 PM, DCarlton said:

I don’t.  Been wanting it do it for years.  After reading the thread, I’m not sure I’m ready for another fight.  TBD.  

Do it. I have several friends where the shoulder harness saved their life after having to deadstick the airplane into a field. 1 day of cursing Al Mooney's name to get them installed is worth them saving your life on that one bad day when things aren't going your way.

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