The International Cessna^® 170 Association

Hooker has also been trying to get an STC for their own inertial reel harness for our airplanes. I think he has been working on this for about 5 years, and is navigating the complex engineering hoops the FAA has placed before him. Each year I approach Jack at Oshkosh and ask "is it done yet?" and each year the reply I get from him is "almost, maybe next year". Hookers inertial reel system for the C-170 was to be based on the one he STC'd for the C-180, it was going to be cheaper, and easier to instal than the BAS. I am not sure if this is ever going to happen though with all the FAA red tape he may just give up. Too bad.

Steve
N8293A '53 C170B

It is my understanding that you can install any kind of shoulder harness you want to, whether or not it is STCd and even if it is home made. I thought that was the one practical thing that the FUZZ came up with a couple of years ago.

For those concerned about the inability to reach the flap handle with non-retracting shoulder harnesses:

I normally take off with 20 flaps as a standare practice. I leave the harness just loose enough to reach the button prior to take off. After I set the flaps to 20, I tighten them up just a bit.

In flight, when I retract the flaps, I intentionally DO NOT push the flap handle down so far that it locks. The airflow keeps the flaps in the full up position and when it is time to lower the flaps, you can reach down and grab the middle of the handle to bring them to the first detent. No need to reach all the way to the button.

A note about shoulder harnesses and how they should be worne. They will not do as much good if they are worne loose over the shoulder. In an unrestrained accident there are 3 impacts: the airplane hitting the ground, your body hitting the dash and your internal organs hitting the inside of your body cavity. This 3rd impact is often the source of life-threatening injury. Tight shoulder harnesses keep the second impact from occuring (as severely at least). If the shoulder harnesses are loose, then your body will continue forward and impact the harnesses with similer force as if it hit the dash. They need to be tight to be effective.

The key to surviving crash landing is energy disipation. An impact that decelerates at a rate less than 30 knots per second is considered survivable. That means if you hit the ground at 45 knots, if it takes longer than 1.5 seconds to come to a stop, the chances of life threatening injury are greatly reduced. During the time it takes for an unrestrained body to move from the seat to the dash or forward limit of loose fitting sholder harnesses it is not decellerating and it will "catch up", if you will, and experience higher g forces.

If you have non-retracting harnesses, have a plan (and brief your passengers) that in the case of an engine failure, they should tighten both the lap belt and the shoulder harnesses prior to touchdown.

One of, if not the most significant safety factors of our planes is the ability to actually touch down in an emergency situation with an incredibly low amount of energy - low groung speed. As long as you hit something frangible, the decelerations rates are survivable as long as the occupants are properly restrained.

On a related note, a local family of four ran out of gas inside of a mile final at the local airport a few years ago. The low time pilot did a great job putting the PA-20 180 down in a very short plowed wheat field. The plane stayed right side up and the only injuries were two broken noses and fiberglass imbedded in their faces. Yep, the harness were hanging behind the seats! they are uncomfortable and a pain in the @%#, but they do what they are supposed to do when you need them! I would feel naked in any airplane without them.

Bruce

If you have T-rex arms like mine an inertia reel is almost mandatory to having effective shoulder harnesses. A solid harness would have to be so loose as to easily let my hard head hit the panel.
I have gotten several Field approvals for shoulder harnesses under the
" relaxed certification rules" of the FAA used to encourage the installation of harnesses. Including one installed in a Navion Rangemaster. The main thing they require is the structural integrity to withstand a pull of 500 lbs without any permenant deformation of the aircraft structure. When installing harnesses for the back seats of a 206, it is amazing to see how much the cabin roof moves during the proof load of 500 lbs. I would think that would also provide some "cushion" during a actual accident as the cabin roof flexes to the load placed on it by your body.

I have Hooker harnesses that came with, but when I daydream about ways I can spend more money, the BAS retractables are fairly high on the list. I once heard that the seaplane version of the BAS shoulder harnesses was preferrable over the land plane version for some reason, which now escapes me. It had to do with Alaska and bush flying, both of which are applicable. Any thoughts?

The seaplane version is preferrable IMHO because all four straps separate when released and do not hang up on anything. The land plane version has the shoulder harness straps attached to the lap belt buckle halves which could become a noose inhibiting exit. This is especially dangerous if inverted or you end up under water.

hilltop170 wrote: This is especially dangerous if inverted or you end up under water.

I participated in a ditching training in an Anchorage pool two years ago- it was a great exercise. I can definitiely see the logic in the above point. The coast guard trainer was equipped with either a 4-part or 5-part harness that separated completely when unbuckled. There was enough other stuff to focus on, floating there, upside down in the water. Two take-home points for those who might be interested:
1) keep hold of the seat between your legs to maintain a fixed point of reference, and
2) wait for all rolling and pitching to cease before trying to egress the aircraft.

Guys,
I have found the factory shoulder nut plates, but they appear off center from the seat back. Was the original shoulder harness just over the pilot's left (outboard) shoulder?

Chris

It's directly behind the head.

czollars wrote:Guys,
I have found the factory shoulder nut plates, but they appear off center from the seat back. Was the original shoulder harness just over the pilot's left (outboard) shoulder?

Chris

If you have a B model, and you found two AN3 nut plates inside the spar above two holes, each approximately behind the front seats, you found the right spots for the shoulder harnesses. There are no other nut plates.

PM sent to you

Here's another legal question for the group. Everyone knows the BAS harness system is extremely expensive. However, I'm finding tons of TSO'd inertia reels made by Pacific Scientific that were used in the 300 series Cessna aircraft that look like they would bolt right into my airplane using the existing nut plates. These can be found on the internet far, far cheaper than the BAS system. So if a person uses one of these and makes no modifications to the airframe at all, does that classify as "minor maintenance" by the owner? Or is a field inspection or STC still required?

czollars wrote:Here's another legal question for the group. Everyone knows the BAS harness system is extremely expensive. However, I'm finding tons of TSO'd inertia reels made by Pacific Scientific that were used in the 300 series Cessna aircraft that look like they would bolt right into my airplane using the existing nut plates. These can be found on the internet far, far cheaper than the BAS system. So if a person uses one of these and makes no modifications to the airframe at all, does that classify as "minor maintenance" by the owner?

Yes, to be correct, the installation does not require any further approval than from an A&P who insures the installation meets the criteria set forth in ACE-00-23.561-0. http://www.cessna170.org/forums/viewtopic.php?f=43&t=8 and makes a log entry.

It would be difficult to argue that TSO'd inertia reals attached with existing approved hardware with no other modification didn't meet the criteria since the criteria is much less. I've quite easily gotten my A&P to agree twice to nearly the same installation you are contemplating.

The key to what your considering is how the shoulder harness interfaces with your existing seat belts which are required to meet a higher standard. With my first installation my shoulder harness simply looped around the belts with no modification to the lap belts. In my current installation I bought a complete approved lap belt and shoulder harness assembly that interfaced together. I then rewebed the separately acquired inertia real with the shoulder harness.