0
Zahry

Strong DHT - design flaws, safety hazards, maitenance hazards

Recommended Posts

Quote

Quote


Didn't Strong's report - on the Czech fatality - cite one of the causes as the main canopy volume mis-matched with the volume of the main container?????????




The same Mr. Strong, who had couple of months ago admired HOP330 beeing used with his gear [warning, a gossip]?

I got 10 cases of brew that says Ted Strong said no such thing !!!!!!!!!!!!!!! Let me know.

Share this post


Link to post
Share on other sites
:)
Before you said all these words on Mr. Ted Strong please check youself.

I heard Mr. Ted Strong (SE) & Mr. Bill Booth (UPT) few times at the PIA meetings & at the PIA symposiums that the ONLY reserve & main canopies APPROVED in SE & UPT tandem system are SE & UPT canopies !!!

It is also came up again at the last PIA 09 meeting at the Risk & Management Committee.

SE & UPT tandem systems are APPROVED as a SYSTEM !!!

Be Safe !!!

Share this post


Link to post
Share on other sites

If anyone thinks there is nothing wrong with the system. Here are some photos of the disputed design.

The parts were inspected on friday (25 jump check) and since the inspection we did 7!!! jumps only on the equipment. During the inspection there was no visible damage to the loop, plastic, housing or the stitching. Today morning when I did few random checks I've discovered the damage. What you see on the photos is the housing cutting its way out through the plastic.

How does it happen? The 3 ring system in certain configuration in freefall can push the housing into the plastic. The housings are mostly improperly finished (just cut with exposed sharp edge - every single one I ever seen is almost the same - some worst, some better) and when pushed into the plastic the vibrations from drogue can help cut it its way through. And if there is rough sharp edge (just like in our case here) it goes through like a chainsaw. On the Detail you can see bit of the loop still caught on the rough edge.

It looks to me not just like only one design flaw but a whole bunch together.


This rig has about 1 500 jumps and the housing was changed 3 months ago (the numbers are from top of my head - the exact numbers are recorded in maintenance book @ DZ. If anyone is interested I can provide the exact number of jumps, mothly average and DOM)

I think the same thing in worst stage killed the czech tandem pair. When I've asked czech autorities about the other two accidents Tom mentioned I've discovered there was only one accident involving housing on risers jamming cuttaway (TM cutted the riser loop) and nobody knew anything about the other two accidents Tom mentioned in this forum. - maybe it was just misunderstanding and it happened somewhere else ... but there are other disconcerting fact. I found out the reserve packing card has been provided to Ted and Ted has been reminded he has seen it before publishing his press realease - and than he stated he hasn't seen it (you can check it with czech autorities as well just like me) So, can I trust the rest of it what the SE says?

Also, I was unable to find where the DHT manual states the owner must keep inspection and maintenance records other than usually found in reserve packing card. (I was unable to find where it states the rig has to be sent back to strong after 8 years as well - but it might be just my fast reading ...)

Share this post


Link to post
Share on other sites
Quote

Maybe about month ago before the accident I've heard there were some negotiations between SE and Jojowings to make DHT and HOP330 legal.

Basicaly it is true BUT as far as i know it happened more than year ago. Ask Zibi (the Jojowings man) for more info. It is an interesting story at all and can say a lot about SE´s aproach.

Share this post


Link to post
Share on other sites

Please read carefully the Manual and all Servicebulletins of the Reserve you work on.
Please follow the SB 22 found on www.strongparachutes.com

The Rigger may have looked at everything but without written Report it is almost useless.

similar to the restroom;
no job is finished until the paperwork is done ;)
regards

Share this post


Link to post
Share on other sites
"... I was unable to find where it states the rig has to be sent back to strong after 8 years as well - but it might be just my fast reading ...)

..."

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Service Bulletin 22 explains the factory inspection schedule 8 years, 13 years and 18 years after manufacture.
The factory inspection is written on the reserve canopy's packing data card and stamped on the original TSO label. If the original TSO label is faded, Strong Enterprises often sews on a new label stating the date of the 8-year inspection and reminding owners of the date of the 13-year inspection.
After 18 years, all Strong Dual Hawk components are retired.

Some of these inspections are just common sense. No-one expects a main canopy to be sent back to the factory for an 8-year check because no-one expects a main canopy to last more than 1200 jumps and if you have not made 1200 jumps (150 jumps per year) on your main canopy, you are in the wrong business.
Similalry, the 8-year inspection was introduced after we realized that most Dual Hawk Tandem containers were looking faded, frayed and filthy after 8 years service in the California desert. All that desert grit and harsh sunlight wears out nylon containers rapidly in the Southern California desert.

Share this post


Link to post
Share on other sites
:)
Tomas, if the photos you show on the housing are from a system in service how do you rig & jump that system ???

It looks like the system is packed for use - WHY ???
if there are closing loop fibers on the SHARP end of the housing = Grounded system.

The closing loop itself looks out of service too.

If the housing or any housing on a parachute does NOT have the rounded finish metal cover end it should not be used - see all housing in use on parachutes Sport & Military.

Did you informed SE about that ? or it came up only after the CZ fatality ?

You also said that SE report show some ??? does the TI involved in the fatality was a DHT TI ?

All time you are pointing on unsafe & risky points on the DHT you should STOP rig & jump the DHT's at your DZ - stay behind your words.

Again, did you ever reported SE about all the points you came up with ????

Please put some words about that too.

Be Safe !!!

Share this post


Link to post
Share on other sites
Thanks to Rob and Zhary for the explaination and photos. I don't really have a big problem with the bridle holding the loop in but I think it's less idiot proof than some other methods. Reminds me of something Rob showed once - one of those old fashioned round deployment diapers...

I'm curious about where the closing loop attaches. I can see the cutter on the left side flap. Or is it one of those 2 pin jobs? I'm not so partial on their elastic stowing system either. What is the mbs of that elastic shock cord? What's it's maximum breaking strength?

-Michael

Share this post


Link to post
Share on other sites
Quote

:)
Tomas, if the photos you show on the housing are from a system in service how do you rig & jump that system ???

Quote

I do the rigging with great care. As you figured out the DHT hasn't earn my trust and I'm watching the equipment very closely. The gear doesn't have my trust exactly because of similar sudden component failures



It looks like the system is packed for use - WHY ???
if there are closing loop fibers on the SHARP end of the housing = Grounded system.

Quote

I've closed the rig because I needed to figure out what was going on and how the housing could get close enough to the closing loop and damage it so severely in such a short time. I didn't wanted to change the housing without investigating what could cause the problem. It could be bit contra productive



The closing loop itself looks out of service too.
Quote

it was shredded to pieces - quite scary considering it was almost new



If the housing or any housing on a parachute does NOT have the rounded finish metal cover end it should not be used - see all housing in use on parachutes Sport & Military.

Quote

Tell it to SE and check every housing on DHT with plastic ends. You might have a nasty surprise. When our retired rigger wrote his concerns to SE in 2005 they told him they've put there plastic ends there so the sharp edges can't do any damage ...



Did you informed SE about that ? or it came up only after the CZ fatality?

Quote

It was addressed to SE in 2004 - 2005 by few NZ riggers and the concerns were dismissed by SE



You also said that SE report show some ??? does the TI involved in the fatality was a DHT TI ?

Quote

not sure what you mean in first question - I'll find out about the other one



All time you are pointing on unsafe & risky points on the DHT you should STOP rig & jump the DHT's at your DZ - stay behind your words.

Quote

I'm doing all I can according to our law and regulations.



Again, did you ever reported SE about all the points you came up with ????

Quote

Yes, All those concerns about housings incl. issues with risers were reported to SE in years 2004 and 2005 ... and all dismissed the same way as they dismissed the potential risk involving MR425 and the "reserve" system.

That's why this time I've decided to share my concerns online on public forum instead sending private emails to factory because, as Tom said, internet has a memory and it can't be so easily denied in future.



Be Safe !!!

Share this post


Link to post
Share on other sites
Quote



I'm curious about where the closing loop attaches. I can see the cutter on the left side flap. Or is it one of those 2 pin jobs?

Quote

Hi Michael - it is 2 pin system. If you'll ever come across this system be aware the closing loops must be tight. If the closing loop stretches a bit the pins will became lose and quite easy to knock out (you'll find rigs have loose closing loops quite often before the rig is due for repack - mostly it's happening gradualy)




I'm not so partial on their elastic stowing system either. What is the mbs of that elastic shock cord? What's it's maximum breaking strength?

Quote

I'm not sure what the MBS is for the material strong uses but for shock cord/bungee cord generaly it is min 500 punds and more. In case you'll have a hangup/baglock it is certainly not going to break. (I'm not sure if it is desired feature on reserve system ... ;))



Share this post


Link to post
Share on other sites
Quote


All time you are pointing on unsafe & risky points on the DHT you should STOP rig & jump the DHT's at your DZ - stay behind your words.

Quote

I'm doing all I can according to our law and regulations.




You are saying your "law and regulations" don't allow you to stop jumping something you have found unsafe & risky? Doesn't make sense.

Share this post


Link to post
Share on other sites
:)
Thanks Tomas.

I got your points & thanks for the report.

If SE does not gave you any answer or solution that you as a rigger & TI can move on with it you should STOP the rigs.

Writing all you think & findings on the forum & still move on with no action might be back to you if an accident will happened at your DZ.

I do not know which mains you use in the DHT's better be SE approved mains.

I wonder why your DZO still use these rigs after you the DZ rigger point on the hazards ???

You better think twice on your actions with the rigs with the present housing.

Do not do the best you can - take an action or just back off !!! words or rigging / jumping.

If some NZ riggers reported to SE & still move on with the same issues = I can not understand that.

Does $$$$ are in front of SAFETY ????

What the NZ Skydiving Association or NZ CAA are doing about ?

All was said is regarding your info. only & what you show & write about.

You better call Tom Noonan at SE for a personal chat on the housing issues - he will listen to you.

Be Safe & Smart !!!

Share this post


Link to post
Share on other sites
On conventional freebags the force necessary to pull out freestowed lines is almost zero and once the first closing loop is pulled out running loop releases the pressure and there is almost no force needed to deploy the other one ...... THERE IS NO SAFETY FEATURE LIKE THAT ON DHT
------------------------------------------------------------
for your knowledge the Atom tandem reserve bag from PF/Aerazur also does NOT have any running loop but an elastic band to hold EVERY stow, similar to the DHT one, and I can tell you it works pretty good so far, Atom Tandem is very popular in Europe

Share this post


Link to post
Share on other sites
:)
Thanks.

Tomas does have some valid points BUT he should deal with SE & if he does not have any good answers just STOP the systems till the best solutions from the mfg.

CZ fatality is from a line of errors all around the process.

Safe Jumps !!!

Share this post


Link to post
Share on other sites
Quote

for your knowledge the Atom tandem reserve bag from PF/Aerazur also does NOT have any running loop but an elastic band to hold EVERY stow, similar to the DHT one



Does the Atom system require the use of a MIL-Spec band or can any elastic band be used?

Does the Atom system use shock cord with a locking slide or just an elastic band?
I like my canopy...


...it lets me down.

Share this post


Link to post
Share on other sites
Hi

The Atom tandem reserve free bag have fixed elastic bands for the free bag mouth & the lines order on the TOP of the free bag, the lines after done are covered with a flap which is secured with 2 lines stows.

No rubber bands or shock cord (bungee) on the Atom reserve system.

I'll try to find a photo.

Cheers !!!

Share this post


Link to post
Share on other sites
Quote

Are these hand tacks the only thing stopping the bendix from sliding through the keeper?



>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Yes!
...and if riggers are smart/neat they do replacement hand-tacks deep in the grooves to reduce the risk of flexible housings sliding.
That technique has worked great - for decades - on ripcord and 3-Ring housings.
Modern trends towards Oeteker clamps have been merely to reduce the amount of semi-skilled labour and time in manufacturing.
Sometimes the worst thing with semi-skilled labour is that they "invent" new hand-tacking techniques without understanding the bigger picture.

Reference the Service Bulletin from Para-Phernalia about the correct spacing between ripcord housings and the grommet.

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