Aircraft Fabric Covering: Inspection and Repair

Flashcards covering inspection methods, common defects, and specific repair techniques for aircraft fabric coverings including cotton, linen, and polyester.

Airworthiness Certificate

A document that light aircraft must retain by having their fabric coverings checked at specified periods.

Wood Frames

Light circular or square frames made from celluloid sheet doped onto the fabric cover to provide access at specified positions.

Zip Panels

Access points consisting of two zip fasteners sewn into the fabric in the form of a vee, suitable for frequent inspection or servicing.

Spring Panels

A type of inspection panel particularly suitable for use on light aircraft.

Maule Punch Tester

A spring-loaded device calibrated in breaking strength that equates resistance to strength in $psi$; if it does not puncture the fabric, the material may be considered airworthy.

Seyboth Punch Tester

A testing device that uses a color-coded calibrated scale on a protruding pin; it is not widely used because it punctures a small hole requiring a repair regardless of the indicated strength.

Safe life of fabric

The typical period of time ($5$ - $10$ years) after which aircraft fabric covering may be retired due to deterioration.

Excessive Tension defects

A condition that can lead to the warping of longerons, wing ribs, and trailing edges, potentially weakening the aircraft structure.

Loose Fabric causes

Unacceptable fluttering or rippling in flight caused by inadequate or poor quality dope film, excessive slack during attachment, or a warped structure.

Glass fabric deterioration

A type of material degradation that occurs specifically when exposed to acid rain, dew, or chafing, rather than UV radiation.

Herringbone Stitch

Also known as the 'ladder' or 'baseball' stitch, it is used for repairing straight cuts or tears with sound edges.

Serrated tape width (Herringbone repair)

A $25\,mm$ ($1\,in$) wide tape doped over stitching after a herringbone repair is completed.

Repair by Darning

A repair method for irregular holes or jagged tears, provided the hole is not more than $50\,mm$ ($2\,in$) wide at any point.

Darning repair overlap

The requirement to cover the repair with a serrated fabric patch providing an overlap of $37\,mm$ ($1.5\,in$) from the start of the darn.

Repair by Insertion

A method generally used for damage over $100\,mm$ ($4\,in$) square, where a patch is trimmed to a smooth contour and sewn with waxed hand-sewing thread.

Boot Stitch

A stitch performed with single, well-waxed No. $18$ linen thread, tied with a lock knot every $150\,mm$ ($6\,in$).

Insertion repair seam tape width

Edging tape that must be at least $3\,inches$ ($76\,mm$) wide to cover the seams of an insertion patch.