PA28: Seat-belts and harnesses

[jayemm]

What do you reckon is the safest (within balanced costs) seat-belt/harness for the PA28?

4-point harnesses, a 'standard' lap and shoulder strap?

For standard leisure use (not aerobatics!)

Where can I get them? How much do they cost?

[Flyin'Dutch']

Jayemm

I think there is little doubt that the more comprehensive the method of restraint the better. Otherwise rallye drivers would only have a lapbelt wouldnt they.

However apart from what we may well think is best you have the matter of certification to contend with and I think that there is no mod at the moment for a 4 seat harness for a PA28.

You can of course go along the route of getting such a mod approved by the CAA.

Best talk to your approved mechanic on how to go about this.

HTH

FD

[rustle]

Gotta agree with FD.

Read some of the AAIB reports and you'll see how a 4-point would have made a difference.

Obviously a 5-point (with crotch strap) would be even better - as it stops you "submarining" in heavy deceleration.

[jayemm]

FD and Rustle, thanks. I understand that the more "straps" the better, but I am trying to find the cost/safety balance. So far, the best I could find out about was a 4-point harness costing at least £3k, without any certification.

Do you know of a cost-effective/safety-effective 3-point at a reasonable price?

[Genghis the Engineer]

Check CAP 455 or with Pipers themselves, it'll tell you where the approved suppliers of harnesses are, you wouldn't want something unapproved since that'll invalidate the insurance.

Me, I prefer 4-point harnesses, however you should be realistic. The PA28 is a firmly non-aerobatic aeroplane. I'm afraid that I have crashed a PA28, whilst wearing a 3-point harness, all I can say is I was adequately restrained but it felt at the time less severe than jamming the breaks on in a car so is probably not a useful representation.

G

[john_tullamarine]

It is worth keeping in mind that seatbelt restraint addresses conflicting requirements.

(a) retaining the body within a survival volume ... more is better for forward impacts but may not be better for side impacts.

For instance, you will see on many F/A seats the TARC harness which comes over the shoulders and around the thoracic cage to pick up on the wall adjacent to the hips. In a side deceleration, the normal 4/5 point aerobatic harness does a good job of loading the neck and causing neck damage .. the TARC harness performs far better in this regard as it provides good support for the chest. If you think that this is not a consideration, a local 737 operator not so long ago had a turbine seizure or similar failure on takeoff or landing .. I can't recall which now. The girls in the rear seats, wearing TARC (as I recall), were thrown around very severely in the ensuing aircraft gyrations and suffered a number of minor injuries. It is very likely that those injuries would have been far greater with another style of restraint system.

We ignore, of course, the freak accidents where Bloggs survived because he didn't have a seat belt on, slid down into the footwell just as the roof caved in to the level of the seat backs .... everything in the survival game has to have a healthy serving of reasonably expected events and outcomes .. the dreaded statistics ...

(b) the body, in various directions, has structural limitations not unlike any other structure under acceleration. If the body is restrained too rigidly, then the body will suffer acceleration levels similar to the vehicle. With a restraint system designed to creak, groan and stretch a bit, the body's accelerations can be very much less than the vehicle's and the survivability of an impact can be improved or maintained up to higher impact velocities.

The same reasoning relates to

(i) the use of controlled crumple zones in the forward shell structure of most modern motor vehicles

(ii) the current dynamic aircraft seat standards, particularly helicopter standards where the only way the body loads can be kept under control is to have a collapsible, stroking structure incorporated into the seat.

(iii) the use of explosive steering wheel and dash bags in motor vehicles ...

... and is the reason why a aircraft forced landing into, say, a wheatfield, is a non-event ... at least until the farmer comes after you with a shotgun for the damage to his crop ......