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Posts posted by mark

  2. dpreguy

    I think, if you are face to earth at the time of the release of the main risers as you are flying away in a straight line; if you started face to earth, you would stay face to earth. But I may be wrong.) What am I missing here? What force would cause your body to rotate on it's longitudinal/roll axis? = (The only axis that would produce line twists on a deploying reserve).



    If the jumper's center of gravity is closer to the canopy than his aerodynamic center, he may also rotate on his lateral axis (forward or backward loop) or yaw axis (cartwheel).

    Mark

  3. dorbie

    For those skydivers who jump a repack cycle without an AAD when the 4-year service rolls around that represents a 12.5% lack of AAD coverage, if all other things were equal that would be the statistical equivalent of poor reliability rate, but because it's couched as an informed choice and part of the service plan the risk that represents is never mentioned.



    Most Cypres users manage to figure out which 3 weeks in the 13-month service window works best for them. For example, it's winter now in Minnesota and all the bears are white, which makes a good time for the 4-year service.

    Even f you jump year-round, the 3 weeks it takes for service are about 1.5% of the 4-year cycle.

    Reliability is not the same as availability, and putting the words "statistical equivalent" in front does not make it a good analogy.

    I jump an M2.

    Mark

  5. JWest

    Basically just waiting till the previous jumper was horizontally at 45 away from the plane. I don't use it, I count and everyone on the load usually does.



    You don't use it because it doesn't work? Or just doesn't work as well as counting?

    Also, "usually" means there are cases where at least one person does not use the counting method. What method does that person use?

    Mark

  7. yoink

    In a thread a while back someone mentioned that attaching a main canopy to the risers is something that has to be done by a rigger.

    Is that correct?



    Quit asking that question before you get an answer you don't like.

    In any case, riggers are not required to keep records of work done on main canopies and other non-TSO'd parts. And I just really can't remember who did the attaching.

    Mark

  8. PD wasn't making Navigators in 1992. A Navigator is a 9-cell hybrid ZP/F-111 canopy. What is being sold might be a PD-218 7-cell main. I'd give about $0 for such a canopy.

    FL-1519-R is a Flight Concepts Firelite, early 80's technology (30 years ago!). It is not a PDR-176. I'd value it around $200-300. Maybe. Most people would value it less.

    The RWS (not UPT) Vector II was made before Cypres AADs. It may have been modified to accept an AAD. Tf not, you will need to send it to UPT for alteration, or find a master rigger to alter it for you. The RSL may be a factory installation or other authorized installation, or may have been added after-market by someone else. If it is in good condition, complete with risers, 2 bags, 2 pilot chutes, etc. and if it doesn't need additional work, then it might be worth $200-300.

    This system is old enough to go out drinking. You should just go out drinking with it. If you buy this rig, you should plan to be the last owner.

    However, you might get lucky, and you might break even with the money you would otherwise have spent on rental gear. If you think you're lucky, then buy a lottery ticket, but send no money to the seller before he ships it to your local rigger for inspection. That's $0. No shipping, no half-down, no nothing.

    Mark

  9. millertime24

    ******

    Quote

    By only doing it once I keep the risk lower



    that is some fucked up logic right there



    It's actually math. If you have a 5% chance of something going wrong and do it once. You have a 95% chance of getting away with it. If you do the same thing 10 times while maintaining the 5% risk you have a 60% change of getting away with it every time. If you do it 100 times while remaining at a 5% risk factor you have a .5% change of getting away with it every time. But the more you jump the risk factor goes down because the experience factor goes up. I have no clue what the statistic is for 'camera incidents/camera jumps' is so I can't give you detailed numbers but I can safely say that it is far less than 5%.


    You haven't by chance taken college statistics have you? You do realize each event is its own set of odds. It isn't cumulative otherwise people would be raping a roulette wheel.

    I never thought I'd be writing this: I agree with JWest.

    Simple version, coin toss with a fair coin. What are the odds of going some number of tosses before getting heads?

    With 1 toss, the chance of getting heads is 50%.
    With 2 tosses, the chance of getting the sequence T-H is 50% x 50% = 50%^2 = 25%.
    With 3 tosses, the chance of getting the sequence T-T-H is 50%^3 = 12.5%
    With 4 tosses, the chance of getting the sequence T-T-T-H is 50%^4 = 6.25%

    JWest's example: the chance of success (the equivalent of tossing heads in the simple example above) on any one event is 95%. The chance of success on each of 10 events is 95%^10, approximately 60%. The chance of success on each of 100 events is 95%^100, about 0.6%. The calculation assumes the events are independent, that success on one does not affect success on others. However, as JWest correctly points out, the events are not truly independent, and the chance of success probably increases with experience.

    BTW, some unrelated fun with statistics: Mr. Poisson says the chance of you having a malfunction on your next jump is greater than going any number of jumps and then having a malfunction.

    Mark

  10. councilman24

    I tried to have rigging committee write an alternative rigger certification system to be ready when the FAA is ready to change, as well as be a model for countries that needed one. When I lost the chairmanship that effort ended.



    Not exactly. There were at least two meetings where we discussed possible models, but there was not a consensus on content. There was at least one complete proposal brought forward, and I can revive it again at the next meeting.

    There are several issues that need to be resolved:

    1. Do we want a universal rigger certification system that would be accepted in the US as well as other countries? Is the FAA likely to accept such a system, and if not, would other countries adopt FAA standards? Who would be responsible for oversight? I think this is the most difficult issue, since even within the EU there is no standardization.

    2. Do we want to add another certificate, "Rigger", to rank just below a Senior Rigger, and authorized just to pack mains without supervision (or, Canadian-style, to also pack reserves and do repairs not requiring a sewing machine)? What is the likelihood the FAA will be willing to develop the certification standards and tests required for such a rating? What is the likelihood the FAA would allow USPA or PIA to administer a national or local program, and where would the funds come from?

    3. What should the ratings be? Currently, the ratings are: back, seat, chest, and lap. Should there be no ratings? A rating for ram-air and a different rating for round? A rating for sport and a different rating for pilot emergency rigs? If a sport rating, should there be a separate rating for tandem? Should there be a requirement for type-specific training, so, for example, if all you've packed is Vectors you'd need supplemental training to pack a Javelin?

    4. What provision, if any, should be made for periodic recertification?

    5. Should the FAA ditch the whole rigger certification business altogether? If the FAA is not in the rigger business, then it is even less in the skydiving business, which means we would fall further outside the FAA's mandate to promote aviation. What happens to airport and airspace access and other benefits of having the FAA on our side?

    Right now we have an imperfect system, funded mostly by Other People's Money, Other People being mostly the non-skydiving, non-rigging public.

    -Mark

  11. virgin-burner

    i think there's even something like a step-through as to describe best.



    Can't be a step-through if the lines were assembled correctly and the lines on the rear riser are still correct.

    Mark

  13. keithbar

    I'm 6ft 4 and 260lbs. I have a talon with a raven 3 with like 3 repacks on it and a 229 Safire. probably be perfect for him. but young kids today are scared of the old school stuff.:D



    RI Talon is TSO'd for exit weight of 254. If you are jumping this rig, your exit weight is around 280 or higher and you are a test jumper.

    -Mark

  14. jbscout2002

    You've stumped me, Mark. I don't know of any regulatory settings for AADs in regards to students. Just that an AAD is required. My AAD is an M2, and on student mode, it will fire at 1085 ft. if the fall speed is greater than 45 mph, the at 660 ft. if the fall speed is greater than 29 mph. It then deactivates at 145 ft.



    Is a firing altitude of 1085' adequate for my customer?

    Mark

  15. jbscout2002

    I do know that if the weight falls within the maximums listed on the placard, then everything else IS sturdy enough.



    Sturdy enough, yes. But that is not all.

    I have a big-boy rig with a TR-335 reserve (TSO-C23d, rated for up to 430 pounds). What altitude should the AAD be set to fire at? Does it make a difference that the user has been clocked at 160mph (which is less than the placard limit) in stable face-to-earth freefall?

    Mark

  17. Unstable

    I would generally recommend against the M2. I was an Argus user back in 2006-2007 when they had only been on the market for a few year, and that didn't turn out too well. Cypres 2 and Vigil 2 have proven themselves to such an extent that the risk of you having an expensive paperweight is minimal.



    On the other hand, the US distributor for M2 is Alti-2, a company with a very good reputation. And we hope everyone has learned something from the Argus experience.

    -Mark

  18. skytribe

    So you guys are arguing the toss about wording which is to a large part irrelevant.



    It is not irrelevant even for master riggers. If it is a repair, I can just do it. If it is an alteration to a TSO'd component, I must get permission -- and that can be a lengthy process.

    Mark

  19. masterrigger1

    Quote


    Why would you choose to interpret "configuration" to mean "manufactured configuration" instead of "approved configuration"?


    Because mains do not have to be approved.



    Why would you choose to interpret "configuration" to mean "manufactured configuration" instead of "designed configuration?"

    And specifically with respect to chest straps, which manufacturers specify exact lengths as opposed to a range of lengths?

    Mark

  20. masterrigger1

    Here you go:

    8300.10, Paragraph 13, b...
    B. Any change to the configuration, method of operation, or method of packing the main parachute, up to and including the main canopy attachment links or the male end of the quick release fittings, is a main pack alteration. Any main parachute alteration that affects the strength or operation of the auxiliary parachute, including the harness, must be regarded as an alteration of the auxiliary parachute and handled accordingly.



    That's it?

    Why would you choose to interpret "configuration" to mean "manufactured configuration" instead of "approved configuration"?

    BTW, the correct reference for your quote is 8900.1, Volume 8, Chapter 5, Section 8, paragraph 8-476, subparagraph B.

    Mark

  21. masterrigger1

    Quote

    Please provide the reference for your definition.

    That came from 8300 Volume 2, Chapter 28 IIRC, which was the inspector's handbook. It also is a test question in the FAA Parachute rigger's written test and has about 4 different variants of that question.



    8300.10 Volume 2, Chapter 28: "Certificate Parachute Rigger/Added Rating" has been withdrawn, and the contents incorporated into 8900.1. It didn't contain the definition you claim anyway. 8900.1 also contains no definition of alteration like the one you claim. But I'm sure it's there somewhere. If you keep looking, you will find it! When you do, please quote it.

    The written test has a number of Part 65 questions on alterations (who may do alterations, which ones are required to be logged), and 4 questions which give examples of alterations (dyeing a canopy, installing an AAD, and 2 questions on plating hardware). There are no questions that ask about the definition of "alteration" or that suggest that changes to the as-manufactured configuration are alterations.


    Mark
    a not-so-young rigger
    over 35 years of experience with parachutes and parachute regulations

  22. masterrigger1

    The FAA defines any change from the original manufactured configuration an alteration, so that is where I was coming up with the term alteration.



    I'm not sure that's correct. For example, patches on a canopy are usually repairs, not alterations, even though the manufactured configuration is patchless. Please provide the reference for your definition.

    Mark

  23. masterrigger1

    Back to the OP's question; Altering the length of a chest strap is plain and simple an alteration which a Senior rigger cannot do with or without any manufacturer's BS.



    Except that the OP didn't use the word "alteration." If the manufacturer's TSO drawings/specifications allow a range of lengths, and the result of shortening the chest strap is within that range, it's a repair not an alteration. I tend to think it's probably a major repair, master rigger territory.

    On the other hand, there are rigs made without turn-backs on the chest strap, and I don't know of any cases where a chest strap actually stripped out to the turn-back. Some testing I did recently showed the typical load on a chest strap during opening is around 20 or 30 pounds or so, most of which occurs just before the slider comes down. I could be persuaded that there may be designs where shortening the chest strap might be elementary enough to qualify as a minor repair.

    Mark

  24. masterrigger1

    Remember that it was written by the two youngest DPRE's out there.



    What role, if any, did you or people you know play in this quote from AC-1052D para 15.(c).(2) which did not appear in any PIA or USPA contribution to the AC:
    Quote

    "The riggers must be aware that any repair on a TSO canopy is a major repair"


    I already know the answer. I'm just asking you to share what you know.

    Mark