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Vans RV-8 G-JBTR
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Date: 12-16-2006
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Number of Hours: 1.00
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Manual Reference:
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Brief Description: Primer Wars - The Directors Cut
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I have elected to be slightly contrarian regarding the primer to use. Tradition dictates the carcinogenic two part epoxy or Zinc Chromate primers. I am concerned about the health aspect of using these primers and plan to use Bullseye 123 water based primer sealer. Most of the aircraft parts are covered in pure aluminium, called Alclad and in theory don't need priming. I know that this is an emotive subject and I have spent many hours looking at the pros and cons and came accross Bullseye 123, a domestic and industrial sealer primer.
In December 2005 I painted a peice of aluminium with it and it has been in my Pembrokeshire garden a year and appears to be extremely robust. It can be diluted 10% with water to aid spraying (my sample was hand painted as I didn't have a spray gun at the time). I suspect it will be a bit heavier than other conventional primers but as it is water based the risks are so much lower and I'm prepared to pay that price.
The Standard Aircraft Handbook, page 233 on Corrosion Detection and Control, states "Nearly any durable coating that creates a moisture barrier between a metal substrate and the environment will help control or prevent corrosion. Paints, waxes, lubricants, water displacing compounds, penetrating oils, or other hard or soft coatings, can provide an effective moisture barrier".
Image One - Left to Right - Self Etch primer/Alclad Scratched/Alclad/Bullseye. Notes - The self etch primer came away due to that section not being properly prepared. The scratched Alclad shows evidence of mild corrosion. The neat Alclad is fine and the Bullseye is stuck solid after the simple preparation of wiping with meths.
Image 2 - One 45 degree bend down and up and the self etch primer creased.
Image 3 - Ten 45 degree bend cycles and no sign of creasing.(bottom right). Piece cut out, bent and soaked in AVGAS for 8 days without any change in structure. Top left of test peice Bullseye removed with nail varn
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Test Piece
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Self Etch One Bend
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Tests Passed With Flying Colours
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