Shoulder harness install without STC

Fearless Tower

Fearless Tower

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Fearless Tower
Can someone knowledgeable refresh my memory on what is required to install a shoulder harness in an aircraft that doesn't have an applicable STC?

Is it considered a minor repair, or do you have to go the 337 route?

I remember the FAA put out some guidance a few years ago, but looking for some current interpretations.
 
We did a 337 when we installed shoulder harness in by Beech.

The company is no longer in business, wondering if I will need to do another 337 if I ever change the out.
 
If you go to the Hooker page, you can see that the official FAA position is pretty weasel worded. Hooker pointed me to the acceptable data for the Navion.
 
Fearless Tower said:
Can someone knowledgeable refresh my memory on what is required to install a shoulder harness in an aircraft that doesn't have an applicable STC?

Is it considered a minor repair, or do you have to go the 337 route?

I remember the FAA put out some guidance a few years ago, but looking for some current interpretations.
Click to expand...
Discuss this with your A&P-IA, if they are in doubt, call their PIM at FSDO.
And remember that the AC 43-13 is not approved data for aircraft that have their own maintenance manuals.
 
GlennAB1 said:
Check out AC21-25A
Click to expand...

This has no bearing on the new safety up grade rules used now by the FAA.

Many of the up grades we have completed in the past, have now been made a minor alteration totally with in the approval of the A&P-IA on a form 337 and returned to service by signing block 7, which then is made a portion of the aircraft's history record.
 
I'm thinking if adding a "Y" type shoulder harness in a pre 9/14/69 normal category aircraft. In table 9-1 I see the minimum static test load of 704 pounds. Is the shoulder harness static test load (0.4)x(704)x 1/cos angle ?

How was the number 704 derived? 9 x 170lbs = 1,530lbs and 0.4 x 1,530 = 612 lbs
AC 23-17C replaced AC-23-17B says same thing.

"The FAA does not encourage the approval of retrofit shoulder harness installations as
minor changes. The preferred methods of approval are STC or field approval.
However, the FAA should not forbid the approval of a retrofit shoulder harness
installation as a minor change in: 1) the front seats of those small airplanes
manufactured before July 19, 1978, and 2) in other seats of those small airplanes
manufactured before December 13, 1986.
A retrofit shoulder harness installation may receive approval as a minor change in
these small airplanes if:
The installation requires no change of the structure (such as welding or drilling
holes).
The certification basis of the airplane is either 14 CFR, part 23 before Amendment
23-20, part 3 of the CAR, or a predecessor regulation.
In addition, a minor change installation should follow the guidance for hardware,
restraint angles, and attachment locations provided in the following:
AC 43.13-2A, “Acceptable Methods, Techniques, and Practices Aircraft Alterations.”
AC 21-34, “Shoulder Harness-Safety Belt Installations.”
AC 23-4, “Static Strength Substantiation of Attachment Points for Occupant Restraint
System Installations.”
105
AC 23-17B 04/12/05
Installations approved as a minor change may not provide the occupant with the
protection required either by regulation (CAR 3.386) or 14 CFR, part 23, § 23.561).
However, a properly installed retrofit shoulder harness installation is a safety
improvement over occupant restraint by seat belt alone."


......blah, blah,blah,.......


"We conclude from these rules that if a shoulder harness is not required equipment,
it is not essential to the safe operation of the airplane. Therefore, CAR 3.652 and
§ 23.1301, before Amendment 23-20, should not be used as a basis to prohibit
shoulder harness installation by minor change. "
 
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Fearless Tower said:
Thanks, that's what I was looking for. Now just need to figure out the best way to attach it in the aircraft.
Click to expand...

On the cherokee, a doubler on one of the structural frame elements then rivet to the doubler.
 
Tom-D said:
This has no bearing on the new safety up grade rules used now by the FAA.

Many of the up grades we have completed in the past, have now been made a minor alteration totally with in the approval of the A&P-IA on a form 337 and returned to service by signing block 7, which then is made a portion of the aircraft's history record.[/QUOT


.??? If it's a minor alteration why does it require a form entitled major alteration or repair?
Click to expand...
 
If you read the various pieces of guidance, you'll see the FAA gives a fair amount of flexibility here as a means of encouraging the installation of shoulder harnesses in airplanes without them. While the FAA might "encourage" the STC route, it's plain that it's simply not required in some circumstances (age and no structural mod).
 
unsafervguy said:
.??? If it's a minor alteration why does it require a form entitled major alteration or repair?
Click to expand...

I wondered the same thing when I read that. I'm guessing it is an accidental miswording on Tom's part.
 
unsafervguy said:
Tom-D said:
This has no bearing on the new safety up grade rules used now by the FAA.

Many of the up grades we have completed in the past, have now been made a minor alteration totally with in the approval of the A&P-IA on a form 337 and returned to service by signing block 7, which then is made a portion of the aircraft's history record.[/QUOT


.??? If it's a minor alteration why does it require a form entitled major alteration or repair?
Click to expand...


Simple documentation of how it was installed. So the next A&P-IA can't say it was a major undocumented.
Click to expand...
 
The Navion is a difficult beast to install shoulder harnesses due to the sliding canopy. While it's not optimal, the usual way is to attach to the structure BELOW the canopy (imagine you are sitting in a bathtub and you want to attach it to the lip of the tub. I've seen some fittings added behind the rear seat for the front seat harnesses, but there's a nice structural tube that passes behind (and supports) the rear seats. Mine just loops around that. I took the FAA "less recommended" weasel way out.
 
Tom-D said:
unsafervguy said:
Simple documentation of how it was installed. So the next A&P-IA can't say it was a major undocumented.
Click to expand...


really just messing with you on that one tom.

on shoulder harnesses I consider that a major alteration that the FAA has decided that 43.13 and the IA's judgement is approved data and should be submitted on a 337.

bob
Click to expand...
 
unsafervguy said:
on shoulder harnesses I consider that a major alteration that the FAA has decided that 43.13 and the IA's judgement is approved data and should be submitted on a 337.

bob
Click to expand...

How else would you get any info into the aircraft's history records?
 
if its a minor alteration, and 43-13-2b chapter 9 gives examples of installations that are minor alterations, such as an installation that clamps around a tube requiring no drilling or welding, it does not require a 337. a simple log book entry documents it. a 337 is ONLY required when it is a major alteration. hence the title Major alteration or repair. If drilling or welding is required then it is a major alteration and a 337 is required.
 
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