I was getting ready to fly my Great Planes Cessna for the fourth time. I did a surface check and throttled up to check the transition of the Saito 56. All checks appeared normal. As I was taxiing on the runway I got a feeling that I needed to bring the plane back and check the transition one more time. I couldn't see or hear anything wrong I just had a feeling to recheck.

As I throttled up the fuselage filled with smoke. At first I thought the onboard ignition battery may have had a problem. After pulling back the throttle the smoke cleared about 30 seconds later. Having witnessed a battery fire before I left the plane on the mat and took a break. Because it was getting late I decided to call it a day and look for the problem at home. A check inside the fuse revealed nothing out of the ordinary.

After removing the cowling the problem was apparent. The muffler had come loose and was pointing directly at the firewall instead of down the muffler shield area. Needless to say the muffler will go back on with Teflon tape and German torque.