pdf Gfa ad 278 issue 3 2016 03 7 Popular

SAILPLANE REFINISHING ALTERNATE MATERIALS AND PROCESS

Applicable to all Sailplanes/Powered Sailplanes having a structural FRP, wing, fuselage, tailplane or control surface skin finished in GEL Coat. Based on in service experience it has been found to that Vorgelat gel-coat is not suitable for the Australian operating environment. This Airworthiness Directive is addressing the following 2 points;

1.   Experience gained through Australian registered sailplanes and powered sailplanes finished in Vorgelat gel coat has demonstrated over time that it is not a suitable finish for the Australian operating environment. GFA AN 69 provides details of the failure mechanisms of polyester gel coats.

2.   There has been a need to redo unsatisfactory refinishing jobs because either insufficient gel-coat was removed or the chosen new finishing system was inappropriate.

Irrespective of the type of finish being removed the quality control process must ensure that; 1. All cracks likely to have transferred from the external finish to the structure are found and removed. 2. All damage incurred by removing cracks and general sanding is found and repaired. 3. The finished sailplane has correctly balanced control surfaces and the whole sailplane weighed and appropriately placarded. 4. Logbook entries that confirm for future owners/operators that the refinishing process was properly undertaken. Issue 3 of AD 278 seeks to provide details of acceptable materials to use when refinishing sailplanes. Note: This AD is to be read in conjunction with the requirements of GFA Manual of Standards, AN 69 and Basic Sailplane Engineering (BSE).