Sample Repair 2
Flap bare metal respray.
RH wing flap removed from Cessna 152. A lot of spot corrosion done on it in recent years. Would benefit from a bare metal re-spray. Also an opportunity to apply SEB 95-3 Rev 1 to flap roller housings. Stripped several layers of paint using chemical stripper and plastic scraper. One rivet head had corroded through and came away with the paint. This had to be drilled out and replaced with a Cherrylock rivet as there is no access to buck a solid rivet. Service Bulletin SEB 95-3 Rev 1 requires insertion of stainless steel washers between the rollers and the roller housing, inspection of the flap roller housings for scoring caused by contact with the flap rollers and also requires Dye Penetrant testing to check for fatigue cracks which could arise from the stress concentration created by circular grooves/scoring, if present. Grooves can be blended out if less than 0.020" deep. Given that we are stripping the whole flap anyway for painting, this is an ideal opportunity to do the NDT. Also a good time to have a look inside the flap using the boroscope, to check for corrosion inside. It's not part of any SB or AD but no harm to use the dye penetrant on the flap pushrod attachment bracket as well because any fatigue cracks there, could result in the pushrod detaching from the flap which would allow the flap to slide into the fully deployed 30 -degree position, which would cause asymmetric drag making the aircraft very difficult to handle. Also a good opportunity to inspect the flap rollers and bushings for wear. McFarlane make a kit (MCSK100) which replaces the Aft Inboard roller installation only and this is covered by an STC.
Interior of flap sprayed with ACF-50 for corrosion protection.
First Photo -outside of flap roller housing with Developer applied - no cracks detected. Cracks would show up as a red line in the white developer.
Second Photo - the Dye Penetrant system has 3 components - (1) Cleaner to degrease the surface (2) a water soluble red dye and (3) a white developer applied after excess dye is removed.
Third Photo - flap after the extremely tedious job of removing 30 and possibly even 40 years worth of paint!
Fourth Photo - Alodine applied to bare metal. Corrosion removed from inside where possible to reach it.