rear seat shoulder harness

[domeier]

Hello C-170 tribe: I'm an A&P doing some upgrades to a client's 1951 170B, and he wants 4-seat shoulder harnesses installed. I've looked through the earlier posts regarding shoulder harnesses, but haven't seen any info on the possibility of installing rear seat shoulder harnesses. Has anyone done this, and:

1) If so, where do they attach to the airframe, and

2) is there a company providing them?

I emailed Hooker Harness yesterday about this, but haven't received a reply. Also, Hooker says on their website that their (front seat) shoulder harnesses don't require drilling through the top cabin skin to attach to the rear carry-through spar, but they provide no details. I also saw there's another company's unit that attaches to the rear door post.

Sorry if I'm beating a dead horse, but I'd appreciate very much to hear pros/cons on different shoulder harness setups, and how the Hooker system attaches to the rear spar without drilling through the top cabin skin. I'd like to avoid doing that if possible.

Thanks

Paul Domeier

[rupertjl]

Cessna has a service kit (SK # found in the library on this site). The problem with the SK kit for the rear is that its roughly $1600 from Cessna last time I looked. I took the drawings provided in the SK kit and made owner produced parts for the metal strap that is attached to the two bulkheads and has the nut plate installed for the shoulder part of the harness. I then bought TSO'd seat belts and installed (well I'm at the installing part of the seat belts right now).

That's my plan to keep my two little girls safe and secure in the rear seats of the plane.

-Jud

[Bruce Fenstermacher]

There are threads on this at least for the front seats. First all 170B models had nut plates in the rear carry through spar for the front seats. I'm not sure what year of B model but at some point provisions where also added for the rear seat.

The nut plate can be added to the early 170s with out it under a service bulletin. You will have to be imaginative how your actually going to do it though with out major disassembly but it probably can be done by a daft and imaginative mechanic. I'm not sure if the back seat belt attachments where covered under the SB.

Other than that for the front seats only you have 3 STC'd choices.

BAS retracting seat belts which cost the most but are probably the best installation. Then Hooker and Wag Aero which have a similar installation with one big exception. The Wag STC requires a hole in the top fuselage skin. So I'd list them in order of preference BAS, Hooker, Wag.

I installed the Hooker system in my A model then discovered the SB for installing the nut plate which is the route I would probably have gone only because it would have been cheaper, not necessarily easier.

I don't have the time to research more for you now but will later today if others don't.

[bagarre]

http://cessna170.org/forums/viewtopic.p ... ss#p104784

Shows a photo of the rear seat shoulder harness mounts in my plane. These are stock and quite easy to replicate. That's an AN3 nutplate in the front that's riveted thru the strap and bulkhead.

Looks strong enough for a one time use.

[rupertjl]

That's what I made as owner produced parts and installed and I'm pretty sure that's what the $1600 SK kit from cessna gives you.

[bagarre]

I put an eyebolt in mine and use it to hold my car keys.
I plan to make a bungee net and use those as the upper anchor points to keep things on the hat shelf.

[domeier]

Thanks for all the excellent advice.

Paul Domeier

[cessna170bdriver]

WOW! I had never heard of provisions for rear seat shoulder harnesses and had never noticed them in mine, but I found some pictures of '98C's interior without a headliner, and lo and behold, there they are.

[blueldr]

By no means did ALL C-170Bs have nut plates in the carry through spar. I had to install them in my "52 model in order to install the BAS harnesses.
The method was to drill the bolt hole and rivet holes to attach the nut plates where you want to have them installed in the bottom of the spar carry through.
Then, in the bottom center of the carry through spar, drill a hole just large enough to insert the smallest proper sized nut plate. Drag the nut plate over to the prepared mounting holes using a magnet along the bottom of the spar. Fasten the nut plates with the proper sized blind rivets.
The above method was directed by the BAS instructions.

[cessna170bdriver]

By no means did ALL C-170Bs have nut plates in the carry through spar. I had to install them in my "52 model in order to install the BAS harnesses.
The method was to drill the bolt hole and rivet holes to attach the nut plates where you want to have them installed in the bottom of the spar carry through.
Then, in the bottom center of the carry through spar, drill a hole just large enough to insert the smallest proper sized nut plate. Drag the nut plate over to the prepared mounting holes using a magnet along the bottom of the spar. Fasten the nut plates with the proper sized blind rivets.
The above method was directed by the BAS instructions.

I knew about the nutplates in the rear spar carrythrough for the front shoulder harnesses - I installed BAS harnesses a long time ago. It was the nutplates in the next bulkhead back that I hadn't noticed before.

[blueldr]

I don't believe that I'd want to install a set of shoulder harnesses to a ring type bulkhead without some other bracing too. in view of the wat the spar CT channel is attached to the airframe, it is a pretty husky attach point in comparison to a ring bulkhead.

[Metal Master]

The nut plate can be added to the early 170s with out it under a service bulletin. You will have to be imaginative how your actually going to do it though with out major disassembly but it probably can be done by a daft and imaginative mechanic. I'm not sure if the back seat belt attachments where covered under the SB.

Bruce?
: Daft (adjective):
Daft; comparative Adjective: Dafter; Superlative Adjective: Daftest
1. Silly Foolish.
" don't ask such foolish questions"
Synonyms: Absurd, Preposterous, Ridiculous, Ludicrous, Farcical, Laughable
: Deft Adjective
adjective: deft; comparative adjective: defter; superlative adjective: deftest
1. Neatly skillful and quick in one movements.
" a deft piece of footwork"
o demonstrating skill and cleverness.
While I consider my self Deft at the things I do, I think I am sometimes daft for doing them.
Or did you really men Daft?

[cessna170bdriver]

Gotta love the English language!

[DaveF]

My '54 B model has rear seat shoulder harnesses. I'm not sure where they attach, but I assume it's the same as David showed. I'll get a picture of the attach points and post.

[Bruce Fenstermacher]

The nut plate can be added to the early 170s with out it under a service bulletin. You will have to be imaginative how your actually going to do it though with out major disassembly but it probably can be done by a daft and imaginative mechanic. I'm not sure if the back seat belt attachments where covered under the SB.

Bruce?
: Daft (adjective):
Daft; comparative Adjective: Dafter; Superlative Adjective: Daftest
1. Silly Foolish.
" don't ask such foolish questions"
Synonyms: Absurd, Preposterous, Ridiculous, Ludicrous, Farcical, Laughable
: Deft Adjective
adjective: deft; comparative adjective: defter; superlative adjective: deftest
1. Neatly skillful and quick in one movements.
" a deft piece of footwork"
o demonstrating skill and cleverness.
While I consider my self Deft at the things I do, I think I am sometimes daft for doing them.
Or did you really men Daft?

Well I really looked daft trying to be deft with my use of a fancy little word didn't I.