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Here are LittleCloud's recommendations for Glider check.
Controlling your wings over time is an important step.
It aims to check that your wings are still able to fly correctly.
On the sticker is indicated the periodicity. The first of the 2 terms reached triggers the need for this control. A suspect behaviour should also lead to control the glider.
You should know that even when not in use, your wings “work”.
Depending on the storage mode and its environment, this work is more or less important.
Remember that the fabrics (polyamide/nylon) and the lines (dyneema or kevlar) do not like heat or humidity, and even less when those two are combined.
Regarding the fabric:
A fabric with at least 600 g of resistance in the Bettsometer test is considered compliant.
No need to go as far as tearing!
Regarding porosity: if under ten seconds, the wing must be tested on the ground (inflation) and in flight.
Measurements should preferably be taken at the leading edge (30% of the chord).
In terms of deformation, only flight tests can validate whether the wing is suitable for flight or not.
Flight test: to ensure that basic maneuvers (collapse <50%, frontal <30%, brake-induced stall) do not trigger a parachutal phase. When the latter is intentionally induced, if it is not stable, it must maintain a speed range with brakes above 12 km/h.
Regarding fringes on inter-cell holes: if they exceed 5 cm, a flight test is needed to verify that the structure is not deformed.
Be cautious about estimating the lifespan of your wings based solely on porosity measurements.
It’s worth noting that porosity evolution is not linear. We have seen wings “rejuvenate” between two inspections carried out by different centers!
Regarding the lines:
Trim control is essential.
Checking the brake clearance is equally critical!
We allow a tolerance compared to the factory rigging sheet.
A deviation of 20 to 30 mm between the A and C lines is acceptable (resulting in a higher angle of attack than the control sheet, depending on size and aspect ratio).
Note that the production tolerance is approximately 10 mm per row.
Measurements are taken under a 5 kg load.
Regarding line strength:
It is forbidden to break upper Dyneema lines.
Strength calculation:
The load test standard requires 14G of the maximum PTV (Pilot Takeoff Weight) on the sum of the “aged” lower lines.
We therefore recommend using this value as a reference: the total strength of the lower lines must be at least 14 times the maximum PTV of the tested wing.
In case of line replacement, they must be replaced symmetrically.
Measuring the symmetrical line is also a recommended method to check its condition over time.
The timing plans and materials are here:
https://drive.google.com/open?id=1sSWP4f-WQnDVfD-TsS6yhBEG0o4J50b_