PIPER COMANCHE SERVICE MANUAL k, Mask ara around hole with tape and paper to protect ""mee.,Cut I piece of fibCIJIW mat about one inch larger than the hole and one or more pieces of fiberJiass doth two inches IUJer thoin the hole. Brush catalyzed resin over hole. lay mat over hole and wet out with catalyzed rain. Use a ~ublnJ action with brush. Then apply additional layer or layers of fiberJluI doth to build up patch to the surface of srrueture, Wet out each layer thOf'OUlhly with resin. I. With a squeette or broad knife. work out all air bubblel in the pitch. Work from center to edge. Pressinl patch finnly apinst the strUcture. AlJow patch to cure for 15 to 10 minutes. m.
As soon as the patch bqins to set up. but while still rubbery. take a sharp knife and CUt away extra cloth and mat. Cut on ouaide edJe of fcatherina. Scrip cut edps of ItI'\I.CNt'C. Do this before cure is complete. to save exna sandi",. Allow patch to cure ovcrrUtht. n. Ualll dry 80 ,nt sandpaper on a power sander or sandi .. block. smooth patch and blend with Nrroundiftl surface. Should air pockets appear while andina. puncture and fUl with catalyzed resin. A hYl)odmnic needle may be used to rill cavities. Let cure and raand. e. Mix catalyzed rain and work into. patch with r.,.en. Smooth carefully and work into any awicўs. p. Cover with cellophane and squCClft smooth.
AUow to cure completely before removing cellophane. Let cure and resand. q. Brush or spray a coat of cawyzed resin to sal patch. Sand patch. fmish by priming. "ain sanding and applying color coat. NOTE Brush aDd hands may be cleaned in solvents such as acetone or methylethylketone. If solvents ate not available. a srro .. solution of detClJC1lt and warer may be used S('t forth in FAA Advisory Circular 43·13·1. To wist in makina repain andlor rcplacemenu. Figures 4-08 thtu ...13 identifies the type and thickness of various skin mucri&luscd. Never make a skin replacement or patch plate from material other than the type of the oriJinal skin, or of a different thickness than the original skin.
The rCl'air must be IS srronc IS the oripnal skin. However, flexibility must be retained so the surrounding areas will not receive extra stress. 447. Sc:ucrural Repain. Stnacmral repair methods used must be made in accordance with the regulations It may be necessary to CUt access holes to make skin rcpain in some areas of the airplane. Refer to Figure ~l'" for rypicalaccess holes. WARNINC NO access holes are permitted in any control surfaces. WAJtHINC The use of patch plates for repairs of all movable tail surfaces is prohibited.
The usc of any finer material normally used for repair of minor dena and/or muerials used for filling the inside of surfaces is also prohibited on all movable tail surfaces. STRUCTURE ISSUED: 8/18/72 1 E22