Last flight I dropped in at the local field and a mate commented in 'typical 2-stroke clatter'. I hadn't noticed it in the air as my headset is pretty good at passive noise cancellation, the little F23 runs quite smooth, so I didn't pay any attention to his comment.
But flying home I paid more attention, heard some clatter and felt some vibration that was not normal.
I found a sweet-ish spot in the engine rpm and landed back home after about 5 minutes.
On initial inspection one of the mount straps was clearly broken around the securing washer.
As I released the springs at the exhaust flange, the muffler fell off, hanging by the EGT probe cable.
Talk about lucky...or possibly foolhardy by not checking immeidatelymy mate made the comment.
Both mount straps completely failed, and evidence of hammering and cracking around the tube end that mates with the exhaust spigot.
I always give the exhaust/mufflers a good VI and shake during pre-flight- there was no noticeable looseness, but it must have been progressively failing over more than just today's 1 hour flight.
Off to an exhaust shop for repairs to the tube and mounts.
Will I do anything different in future? Listen to my mates, pay special attention to the exhaust system, perhaps safety cables/straps around the muffers?
Edit: And keep away from the <2000rpm shakes except for a short idle check pre-takeoff.