There has been a lot of interest in the access hatch modification (TN 278-21), expecially from new owners. Schempp-Hirth has been posting Technical Notes
on their web site, but the older ships have not recieved enoough attention. TN 278-21 is not there, only a reference to it.

However, James Huff sent a copy to the email group. To see it click Technical Note 278-21 (install Adobe Reader).

Comment by John Giddy, #672, Australia:
My Std. Cirrus has a spring ball catch to retain the hatch cover rather than the Dzus fastener. This looks better, as nothing shows on the outer surface, and no tool is needed to open the hatch - just a tap from inside with the fingers of the left hand. If you are worried about the hatch coming open in flight, the joint can be sealed with the usual wing root sealing tape. (I haven't found it to be necessary) I suggest using the largest dimensions for the hatch. Gives more room for manoeuvring your hand and arm.