Acro Image

Aerobatics Server

ACRO E-mail Archive Thread: Peter Chapman parachute notes (re-post)

[International Aerobatic Club] [Communications] [Aerobatics Images]

Disclaimer: These aerobatics pages are developed by individual IAC members and do not represent official IAC policy or opinion.

[Usage Statistics]


ACRO E-mail Archive Thread: Peter Chapman parachute notes (re-post)



                


Thread: Peter Chapman parachute notes (re-post)

Message: Peter Chapman parachute notes (re-post)

Follow-Up To: ACRO Email list (for List Members only)

From: Herman Dierks <dierks at austin.ibm.com>

Date: Wed, 05 Feb 1997 01:37:22 UTC


Message:

   I am reposting this note as I already had one request for it.
 Herman
> Date: Tue, 3 Dec 1996 21:53:14 EST
> From: Peter Chapman <PMCHAPMA at MANSCI.watstar.uwaterloo.ca>
> Reply-To: Peter Chapman <PMCHAPMA at MANSCI.watstar.uwaterloo.ca>
> Subject: Re: Possible Parachute Problem 
> On Mon, 2 Dec 1996, Dave Swartz wrote:
> 
> > Does anyone no the specific parachute make and model that failed in the
> > Sukoi 29 accident this year?
> 
> Until someone with facts replies, my GUESS is that it was a National 
> Phantom 24. The '140 kts at 188 lb' mentioned in the Nov. Sport 
> Aerobatics corresponds fairly well with a stamp on a 1986 Phantom 24 I 
> saw. It stated:
> 	188 lb max at 160 mph
> 	164 lb max at 170 mph
> 	141 lb max at 180 mph
> And 140 kts is close to 160 mph. 
> 
> The Phantom 24 is also stated to have a general max. suspended weight
> limit of 188 lb. Other Phantoms have other weights listed. That "188"
> figure doesn't seem to crop up in other companies' literature as best I
> can tell. That includes Strong, NAA, and Butler. I am working from a
> variety of sources, however, up to 5 years old. 
> 
> Like many round canopies, the Phantom series (in later versions named 
> Phantom Aerostar) were certificated under TSO C23b. The test methods for 
> this TSO were a little soft, in that a canopy could pass without anyone 
> being quite sure what loads it was actually experiencing, and that some 
> quite lightweight canopies could pass the tests. 
> 
> Within C23b, the "Low Speed" category was really lightweight, while the 
> "Standard" category was better. The Phantom 22 is Low Speed, the larger 
> sizes are Standard. Canopies certificated as Low Speed were limited to 
> 150 mph (I think).  
> 
> There are some round canopies that were designed more recently (or
> recertified?) under the new TSO C23c of 1984. For these, the speed and
> weight limits are more explicitly part of the test process, and there are
> different levels that the manufacturer can achieve. E.g., C23c Category B,
> which is a commonly used level, is placarded in use for 254 lb at 150 kts.
> That's the placard, while actual testing is carried out with 300 lb at 175
> kts. Category C moves up to 175 kts placarded, with tests of 300 lb at 230
> kts. I think there's a newer Category D, which lets the manufacturer go 
> to higher levels as desired. 
> 
> What I am not familiar with are the standards to which military canopies 
> were designed to, and I don't have my rigging manuals around to help.
> 
> I'm not sure if I'm giving the right impression here. The old C23b
> Standard category really wasn't that bad, at least for Standard category. 
> Phantoms and other canopies using that standard worked for lots of
> skydivers and the odd bailout too. On the other hand, some years ago
> Phantoms were all upgraded with extra Kevlar bands. I was told by someone
> at National that there had not actually been any catastrophic failures up
> to that point, but I guess damage had occurred on some deployments. While 
> I wasn't in the skydiving scene in the 70's, there were some Low Speed 
> reserve canopies of the era that apparently did have serious problems 
> from time to time. The limits of light weight construction had been 
> pushed to far.   
> 
> Parachute openings are not perfectly consistent events, so a lot of
> reserve strength needs to be built in to accomodate the occasional odd
> opening. Phantom canopies have been popular because of their light weight.
> 
> I've heard, from talking to Larry Runge on the phone briefly, that Karen
> Diamond has contacted an experienced rigger to write something for the
> magazine on the whole issue. That's not confirmed, but she certainly did
> want to follow it up. 
> 
> Despite the seriousness of the parachute failure issue, bailouts are still
> an uncommon occurrence in acro accidents, and I've never personally heard
> of any other such failures, for what it is worth. 
> 
> I checked the NTSB's WWW database for accident reports that mentioned
> parachutes or bailing out. These cover May 1983 to summer this year. There
> were very roughly 60 reports involving bailouts or attempted bailouts.
> Lots of glider cases, a couple professional flight tests, a few skydiver
> drop aircraft incidents, a few general homebuilt incidents, and maybe
> 15-20 acro aircraft cases. Although all the reports were short, in none
> was a parachute failure indicated. (The numbers are approximate as I
> haven't gone through the incidents in detail.)
> 
> I'm a parachute rigger, but mainly use the privileges to pack my own 
> chute. While I do have some appreciation for the issues here, I've never 
> been involved in a parachute certification program. 
> 
> The simple answer is not to pull outside the envelope. It's tougher to 
> tell what the envelope should be, to avoid a rare but possible low 
> altitude / high speed bailout dilemma.  
> 
> Enough for now,
> ------------------------------------------------------------------------------
> Peter Chapman                           
> Waterloo,Ontario,   Phantom 24 equipped 
> IAC 13591           	
> 
> 


                


© Dr. Günther Eichhorn
Retired
Email Guenther Eichhorn