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    Refilling an A10-A bubble
    From: Greg Herdt
    Date: 2023 Mar 4, 16:26 -0800

    In the late 90's I owned a type C bubble attachment made by the late John Lykx which used an A10-A bubble assembly along with a mounting fork for a nautical sextant and a simple homemade lighting system..  I foolishly sold the attachment about ten years ago and I have been sorry ever since.   Thinking that I might be able to build my own A10-A bubble attachment, I recently acquired an A10-A aircraft sextant that has two bubble assemblies, one of which has a bit of fluid in it, but not enough to form a bubble.  I was able to find an A10A manual online, but it appears to be lacking the details that I am looking for on how to fill or service this particular bubble assembly (I have filled A-12 and AN5154-1 bubbles in the past and this looks similar) and which liquid to use (I have xylene and mineral oil on the shelf for the aforementioned aircraft sextants).

    Is there anyone out there who would kindly walk me through the process of filling these bubble chambers?  I am almost certainly missing something obvious, but want to proceed with caution and do this right.  I have read the excellent article on Bill Morris' site regarding restoration of bubbles, and was planning to use that as a starting point, but it looks as though at least one of the bubbles that I acquired will not need a full rebuild.  I am already looking for a machinist to make the fork attachment that I need, but don't want to go too far down that road until the bubble unit is working satisfactorily.

    I would be grateful for any insights that anyone could share.

    Best regards,


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