A line Maillon fails in Flight

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A line Maillon fails in Flight

Postby Francis Rich » Tue Jul 05, 2011 10:27 am

This weekend an A line maillon opened up during the initial test flying of a wing by our instructor prior to accepting it into the club as that student's second level (Pilot course) training wing.

The maillon was checked for tightness during normal preflight checks but let go at the bottom end whilst the pilot was flying a moderate left hand bank. The open maillon bent straight but held the lines to the webbing long enough for a safe landing. The pilot was not high enough to deploy an emergency parachute which was fitted. Threads inside the nut were seen to have flattened peaks. It is not possible to check these threads as the nut is captive upon them. No pre-flight check can tell you if your maillon bottom threads are poor.

The manufacturer has been contacted and the incident has been reported to the AAIB through the BHPA reporting system.

This Maillon can be identified by the number 316 stamped upon the straight side and a tooling witness mark on the bottom corner. It carries no other markings and has no EN096A or Working Load weight stamped on it.

The manufacturer reports that this maillon is manufactured for Gin Gliders and is fitted to Paramania, Gin and UTurn gliders.

Hopefully this is a single incident of single malformed maillon. The AAIB analysis of the failed maillon and another intact maillon will be reported as soon as it is known and the BHPA intend to issue an interim safety notice within the next few days.
photo.jpg
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Re: A line Maillon fails in Flight

Postby Francis Rich » Tue Jul 05, 2011 10:28 am

Follow up to failed maillon report.
The failed maillon and another, intact, have been sent to AAIB for analysis. First inspection reveals flattenned crests to the thread inside the nut. Whitehorse Flying Club have grounded all flights of wings with this maillon fitted until results of the AAIB tests are known. Wings with these maillons may continue to be flown at Whitehorse if they are fitted with Maillon Rapide replacements that are stamped EN096A and carry a working load weight stamp, provided the manfacturer or dealer has approved their use on their wings and the replacement has been inspected by Whitehorse instructors or coaches.
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Re: A line Maillon fails in Flight

Postby Francis Rich » Tue Jul 05, 2011 11:05 pm

This is the response from Paramania to the failure of a maillon in flight on a Revolution wing:

Dear Pilots

We would like to inform you that we have directly contacted all assumed parties
involved with this maillon. We asked them several times to send us the
hi-resolution version of the original photos of the maillon & to send the
wing/maillon back to Paramania for inspection. It has been four days since their
first posting on this forum and it is ONLY this morning we received an e-mail
response from one of the parties involved - STILL NO INFORMATION or HI-RES
PHOTOS OF THE MAILLON - only that they intend to take the issue into their own
hands and have it sent to the BHPA for inspection.

Unfortunately, due to this delay Paramania is unable to make any further
educated comments or safety advice on this subject until we get further
information. Let's hope it doesn't take too long...

It is a good job that Theron and I occasionally look at the forums... otherwise
'OFFICIALY' Paramania would not have heard anything about this & the issue might
still be in the forums and no real action taken.

If you are concerned about your maillons at all check out our safety notice here
http://www.flyparamania.com/index.php?o ... id=165&Ite\
\
mid=100017&lang=en
Tiny URL link > http://tinyurl.com/safetynotice
OR consult with your local dealer who will be happy to check them for you.

Cheers

Pascal Campbell-Jones


It is not the BHPA but the AAIB who investigate aircraft accidents. This is a "legally reportable" incident and none of us have the option to send aircraft back to their makers for investigation. Individuals certainly have no authority to take photographs to send them. When the AAIB impound an aircraft part it is not the BHPA or individuals who are doing it but the legally appointed authority in the UK

There is no suggestion in Paramania's response to indicate how a pilot should check the condition of the thread within the captive nut. The first indication of any problem will be when the maillon opens under load. There is nothing on the Paramania website to indicate how these maillons can be checked for thread condition within the captive nut.

A simple solution to the problem is to fit EN certified parts to your glider and this has been the normal practice in the industry until now. These cost £3.50 and can be purchased here http://www.s3i.co.uk/rapide_link_delta.php your Paramania dealer will doubtless fit them for free or you can have it done expertly by one of several paraglider servicing houses.


The Paramania response is in error in that their UK dealer was informed within minutes of the incident and it was explained to that dealer why this could not be a simple preflight check error since the nut was on the wrong end of the maillon on landing, as witnessed by three independent witnesses. Paramania had that information the same day as the incident unless their dealer did not pass it on. He has stated that he did.
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Re: A line Maillon fails in Flight

Postby Francis Rich » Wed Jul 06, 2011 9:46 pm

There appear to be (at least) two different riser sets in use on Revo2 wings.
Risers that look like the picture here are now permitted to resume normal flying operations at Whitehorse without modification.

IMG_1513sm.jpg


These are fitted with the Gin maillons that have a plastic insert line keepers (red or black). They have no stamp on them or writing of any kind. These were fitted to revo2 gliders at least up to the end of 2010 and possibly into 2011.
A further distinction is in the trim tab which is printed with numbers.

IMG_1510sm.jpg


Whereas the gliders subject to this notice are fitted with trim tabs that have no printed numbers and have three lines of black stitching across the red tape.

This safety notice no longer applies to Revo 2 gliders fitted with the genuine Gin maillons wishing to fly at Whitehorse subject to an inspection by an instructor or coach and cleared with the CFI.

The safety notice and grounding of gliders now only applies to those fitted with the maillon identified by a number 316 on the long side, a tooling "witness" mark at the bottom corner and the lines kept by a rubber 'O' Ring.

316sm.jpg


Such gliders remain grounded at Whitehorse unless re-fitted with certified maillons and cleared by the CFI, subject to the manufacturer's or dealer's approval.


Paramania are invited to supply serial numbers of gliders not fitted with these maillons to further reduce the number of aircraft grounded.
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Re: A line Maillon fails in Flight

Postby Francis Rich » Wed Jul 13, 2011 11:19 am

Using Non CE/EN362 Maillons
This problem is actually more complex than many people will at first realise, since it is legitimate to CE mark Maillon Rapide type links under two different directives. Even Peguet, the French manufacturers of the Maillon Rapide brand, sell two different types: one is CE marked under the PPE Directive (Personal Protection Equipment) and is designed for use as part of a PPE system for climbing, caving or rope access. The others are CE marked as lifting accessories under the Machinery Directive and are designed for industrial lifting and support applications. PPE is further divided into "falls from heights" (EN 362) and "mountaineering and climbing" (EN 12275)


Links CE marked under the Machinery Directive do not need to be checked by an independent test house before they are sold - the manufacturer can legally self-certify them without the involvement of a third party. Links sold for PPE applications must be certified by an independent test authority (a "Notified Body") and the manufacturer's quality system must also be assessed.

http://ukcaving.com/board/index.php?topic=6161.0


Machinery quality "Self Certified" by the manufacturer
selfCrt.gif


The way to tell the difference between them is that for independently certified links, the CE mark is accompanied by a four figure reference number which indicates the Notified Body who were involved in the quality system assessment at the manufacturer. So, unless the links have a four figure reference number next to the CE mark then they are not certified as PPE.


Personal Protection Equipment certified by independent "Notified Body"
ENCrt.JPG


Wing makers (not Gin) usually install PPE certified links in this critical function.
Peguet claim their Self Certified links are made to the same sandard as their PPE certified and independently verified links. I am reluctant to condemn their use but would not do so myself.
I'd be even less comfortable using non-PPE certified products from other sources, particularly bearing in mind some recent evidence I have seen about the quality of steel currently being used for engineering applications in some eastern countries and of the quality of the engineering and process control of those products.
I avoid using non-CE marked products for anything more critical than hanging a washing line.
Francis Rich
echoing Nick Williams

http://ukcaving.com/board/index.php?topic=6161.0


Gin Gliders use Ansung maillons which are not certified but they have faith in that product and are putting their (very high) reputation behind it.

The maillon that failed in this incident is not an Ansung product. The source of the maillon that failed has yet to be offcially announced (assuming it has been indentified - it surely must have been by now?). Paramania have stated that the product is supplied by Gin. No information has yet been forthcoming from either Gin or Paramania concerning the origin, make or process control of the maillon that has failed.

Whitehorse grounding of all flights fitted with this maillon continues in the absence of further information.
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Re: A line Maillon fails in Flight

Postby Francis Rich » Thu Aug 18, 2011 7:51 pm

A BHPA safety notice is imminent.

The fault in this brand of maillon has been traced to inconsistent gaps between top and bottom thread resulting in the nut winding off the bottom thread as it comes up the top thread to the stop. In the case of the maillon that initiated this report, the condition of the bottom thread was poor, having insufficient material to properly form full thread width.

The fault has been clearly shown not to have been either a loose nut at take off or an overtightened maillon.
The manufacturer of the wing fits this brand of maillon since April and have identified some 40+ wings as needing to have their maillons checked and all further use of this brand of maillon is to be subjected to individual gap measurement by the wing maker.

The grounding of these wings is now lifted at Whitehorse depending on serial number and maillon check.
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Re: A line Maillon fails in Flight

Postby Francis Rich » Thu Sep 01, 2011 9:23 pm

The incident is now concluded and all affected wings may resume flight at Whitehorse subject to confirmation of inspection.

Last notes:

The maillon that failed was manufactured by Pro_Metals of thailand and supplied to Gin Gliders who manufacture wings for various brands. The fault found in the manufacturing process has resulted every maillon in the batch being inspected and a number of maillons being rejected from the batch. Manufacturing processes and quality control systems have been improved. (unofficial quote from a factory worker)

The total number of gliders fitted with maillons from this batch before the new processes were introduced is known and can be identified by the manufacturer by serial number. These numbers have been passed to the various brand companies for action in their distribution chains. (implied in the BHPA safety notice).

A BHPA safety notice has been issued to alert BHPA pilots/wing owners to the recall so that they can have their wing's serial number checked and be refitted with maillons that have been subject to the new quality control. The notice refers specifically to Paramania wings assisting that company in the process of identifying the wings to refit due to difficulties in serial number recording within that supply chain and the location of wings for recall. (my interpretation)

Pilots can pro-actively check their own maillons. (my advice to Whitehorse pilots)

maillonDrawing.JPG


What are you looking for?
A maillon with a gap larger than the design drawing may not contain the threads completely within the nut. Look at the bottom of the nut when closed to see if there are any threads showing.
maillonphotocomparelq.jpg

Measure the gap when fully open.
maillonGap.JPG

Tighten with fingers then 'nip up' with a short spanner.



The threads on the maillon that failed were poorly formed not having the correct number of threads and not having fully formed threads.

maillonThread.JPG


It is not always possible to check whether the theads are correctly formed on a maillon without bending it open to run the nut off the bottom threads (destroying the maillon) as the nuts are not all the same length.

The checking of this maillon batch does not check the thread quality but only the gap. However the maillon that failed was reassembled with its poor threads fully engaged in the nut and the failed maillon withstood a 500kg load test. Pro-Metals maillons may, in general, be well formed but the one that failed was not. I have had no assurance or indication of the quality of the thread captive within the nut on the remaining maillons in the batch whose gap has been found within tolerance and deemed fit for service. It may be that Gin have also binned any maillon whose thread cannot be inspected with the nut fully open.

At pilots' discretion these maillons can be replaced by Ansung, Vinox or Peguet maillons, all of which are widely used in paragliding and are known to have well formed thread within the captive nut. The cost of replacement is around 80p per unit. A and B line maillons are the ones you really care about so that is £3.20 per wing. (make what you will of this).

Finally all pilots should be aware that a maillon that opens in flight does not place you in immediate mortal peril. The force required to bend the maillon to the state in this picture is around 40kg. (P Baldwin)
maillonOpenJPG.JPG


But to open it further to the point that it will release the lines requires considerably more force (currently being tested but probably more than the lines can carry before snapping). The pilot should remain calm and proceed to a safe landing paying full attention to normal landing options and procedures and minimise load on the affected maillon by flying smoothly with low bank angles and spreading the load across the riser set by shortening the trims. (my advice to Whitehorse pilots if they see a maillon open in flight).

The incident occurred on 2nd July in a BHPA school on a wing brought to the school by a student and during the inspection flight of that wing by a licensed instructor prior to the student being permitted to use it. The wing had been delivered directly to the student with no dealer hand over or inspection flight (student account). The incident was reported by the pilot in command and the CFI. BHPA reporting procedures were followed. The incident was categorically not due to the failure of the pilot to ensure tightness of the maillon nut. Nor was it due to any over-tightening of the nut. Both these are very important issues for pilots to be aware of but were categorically not factors in this incident.

All incidents, however apparently trivial, need to be reported through the BHPA reporting system. Internet forums are not equipped to investigate aeronautical incidents and accidents.
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