MIWA PR.LSP+DAF (double-sided cylinder), Lost key, Unlocking the entrance door

"Lost key, Unlocking the entrance door"

It was a request to unlock a double lock. When I arrived at the scene and checked it, I found that it was attached above the door scope. Since the cylinder collar was fixed, the main lock was LSP and the auxiliary lock was DA. We confirmed the unlocking direction of the thumbturn from the relationship between the door guard position and cylinder position.

I was able to unlock the main lock without any problems, but the auxiliary lock at the top is a little more difficult. I felt something strange about the thumbturn, but it didn't seem to be a security thumbturn, so I proceeded with the normal method.I was soon able to unlock the auxiliary lock, but to my surprise, the U9 key was stuck in the double-sided cylinder.

I rarely come across specifications like this, but I couldn't understand the intent of the setting. The only thing I can think of is measures to prevent wandering.

I didn't use a camera or do any detailed interviews, but I found out that the strange feeling I felt when searching for the thumbturn was due to this kind of specification. If you don't have the key inside, the only option is to break the lock.