0
riggerrob

Tandems hooking up before take-off?

Recommended Posts

Quote


I know a few guys who used them on the sigma passenger harness, and they bent the quick ejectors enough to make it very difficult to close them all the way and harder to release them. They are quick ejectors to make them easy to release. If yours aren't I might check them out or how tight you are making them.



Well, here's the thing. UPT claims that the Sigma harness side connection hardware is supplied by the same company as was used for the Vector II harness. I'm sure it is, but the material, or hardening process (if any) they are using for the quick ejectors seems to have less strength than the ones used on the Vector II harnesses. In thousands upon thousands of tandems at our drop zone, we've never seen a Vector II side connector bend. Pretty much all of the Sigma ones bent or snapped in the first month of use. When that happens to every instructor on every harness across the board, that's pointing to materials, not practices. The quick release on my harness I made myself. I don't use the big yellow tabs for the very reason that was stated earlier, in that the student can grab them. I make what are essentially long closing loops and install them past the failure point of the quick release, and then tuck them away behind it where they stow away from prying hands. Only I can get to them. Since we've done that, we have solved our bending issues for all intents and purposes.

If anyone's interested, I'll take photo at the weekend and post it.

As for door openings and connection. If that door is open, I want them connected to me in some way regardless of altitude or other belts. Even if it's an altitude I'm not getting out at, I want to be able to control them near an open door.

Share this post


Link to post
Share on other sites
Quote

When that happens to every instructor on every harness across the board, that's pointing to materials, not practices.



I have worked 7 years at a DZ that does 8000 tandems a year (SIGMA). We take students up to the 500 lb. TSO. I have never seen a bent lower connector. We emphasize proper harness adjustment on a wide variety of body sizes, and do not allow assist devices on the lowers. This leads me to believe that bent lower connectors are due to practices rather than materials.

The upper connectors are load bearing.
The lower connectors are to keep your student from sliding around beneath you in drogue fall.
If you are tightening the lowers to the point that you need assistance unhooking them under canopy you are either over tightening the lowers, or running your vertical adjustments too long.
(In other words you are loading the lower connectors rather than the uppers.)

I know this will be a controversial statement, because I see an awful lot of TI's with lanyards on the lower connectors. But think about it. Uppers are load bearing. Lowers are to center the load laterally beneath you. Not saying leave them loose. They should definately be snug. But you should not have problems releasing them manually without assistance.

I have hauled students up to the TSO on the gear, (which for me means a 300 lb. student) without problems with stability, and without needing assistance unhooking the lowers. I am not basing this on isolated instances, but hundreds of tandems with students 250 lbs. and above.

Share this post


Link to post
Share on other sites
Quick Ejector snaps have always worn out faster than most other MIL-SPEC hardware.
Usually it is the tiny, internal springs that break first.
The United States Air Force reacted to this problem - back in the 1960s - by introducing a screw-in, replacement QE Snap.
Cleaning and oiling them helps, but riggers at tandem DZs should plan on replacing a few QE snaps every year.
For example, Strong Enterprises had a bad batch of QE snaps in the late 1990s, but I have not had to replace any recently.

Share this post


Link to post
Share on other sites
Quote

Quote

When that happens to every instructor on every harness across the board, that's pointing to materials, not practices.



I have worked 7 years at a DZ that does 8000 tandems a year (SIGMA). We take students up to the 500 lb. TSO. I have never seen a bent lower connector. We emphasize proper harness adjustment on a wide variety of body sizes, and do not allow assist devices on the lowers. This leads me to believe that bent lower connectors are due to practices rather than materials.



Normally I'd agree with you, but I've taken the hardware off an old Vector II and a new Sigma, placed them in a vice and subjected them to equal loads using a device to measure pull force. The Sigma tangs bend at significantly lower pull forces than the older connectors, which really just backs up the observation that the older hardware never bent under the same practices. I've tested a new one right out of the box that exhibited the same low resistance to shear forces.

They've also bent under all variations of tightness too, with all of the instructors seeing it in one way or another. Most of us get the students to stand on our feet and take the weight off them before release anyway, so there's not anywhere near as much strain on them as a full load. We also have two UPT tandem examiners on staff to monitor the practices. We also do 5000 plus tandems a year, so we have a good sample.

Now I'm not saying that we might not have been over tightening lateral connections in the past and getting away with it because of the superior strength of the old connectors, but we've reviewed that part of the operation and made the necessary changes.

It's no longer an issue since we changed to using the pull-up type releases, so we're all good. YMMV etc etc.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

0