Control surface seal security is very much overlooked both by pilots
and A&Ps doing daily and annual inspections.

Safety tape, is the tape along the leading edge of the mylar, is
generally good for 2-4 years, depending on the climate and storage of
the glider. The tape may look good, i.e. no part of it is lifting off
the surface, but when you start to remove it you see that the adhesive
has lost its gripping power, and the tape pulls off quite easily, and
is brittle.

If any section of the safety tape has started to lift off it is time to
replace all the safety tapes. Use the stuff sold by our glider supply
dealers, it is well proven and has a better than average gripping
power. Anything to do with control surfaces is not the place to cut
corners on materials. Don't buy your safety tape at Harbour Freight!!

Mylars last a bit longer but their life depends on storage conditions
also. They can get very brittle, and over time the adhesive looses its
holding power. If you replace the safety tape on a regular basis this
presents an opportunity to carefully inspect the mylars. An old,
brittle mylar will likely break if you try to re-curve it.

This stuff is not cheap to replace, but neither is repairing your
glider because of an accident due to loss of control surface
effectiveness.

Most A&P do not understand the critical nature of control surface
seals, especially if they do not look at a lot of gliders. Power planes
do not use this technology and so when they see these seals they just
avoid them for fear of getting into something they know nothing about.

Robert Mudd
A&P/ I.A.
Moriarty, New Mexico