"I had just taken a passenger for a ride. The preflight and run-up were normal as was the full power run-up at take-off. At cruising altitude, I could hear' an occasional unusual ticking sound in the headphones, but at the time it seemed like one the those sounds you get on a dark night or when over water (not in my Long-EZ, of course). Return and landing were normal, as was the taxi in. However, being the ever vigilant, I decided to make a post flight run-up on the ramp. My friend, who is a very highly experienced pilot, was watching. As I was making the run-up, the RPM began decaying and the engine quit! At the same time, my friend called out 'fire!' immediately shut off the mixture and fuel valve and hastily egressed while lowering the nose.
Unfortunately, I had left my Halon extinguisher in the hangar which was about 200 feet sway. ran, retrieved my Halon - the hangar-mate next door brought his and we used both on the fire. I don't know how long it lakes to run 400 feet, but in that period of time the fire had a very good start. Both Halons were discharged and the fire was controlled. I know there was not an in-flight, or taxi-in fire as my friend was watching. There was probably a crack in the exhaust system which was the sound heard in my headset. The post flight run-up probably caused the final separation of the exhaust system and, of course, ,the fire. If I had suspected an exhaust leak, I would not have made the run-up. However, I'm glad it failed on the ground at run-up rather than in the air.
This, of course, is a very serious situation because of the total separation of the right exhaust system and the ensuing fire caused by the direct torching effect of the exhaust emission. The torching effect probably would not cause a fire while flying because of the airflow, however, the metal parts separating from the aircraft is a sure problem. This aircraft has a Lycoming 0-320B engine with a Sport Flight exhaust system circa '84. Total time on system, 225 hours. The engine compartment was uncowled and checked 10 hours previously, with no apparent cracks or breaks. The break was on the right rear exhaust at a point where the small 'S' tubing is welded to the larger straight exhaust pipe. The break was not in the weld. The break was right outside the weld on the larger pipe.
It appears to be fatigue rather than a bad weld. What's puzzling to me is the springs that held the front tubing into the slip joint flange had stretched and given way. So now we have a total separation of the right exhaust system. I'm sending the exhaust system to RAF for analysis. To my knowledge, this is not a common problem with a Sport Flight system. I know the gentleman who produced the original system and consider him to be conscientious and capable.
However, all systems should be checked. In the meantime, I will endeavor, with help from you folks, to determine the cause. The damage is repairable. It was confined to the cowling, rib heat shield, right exhaust and finish on the prop. All systems and components in the engine compartment will have to be checked. I've seen some EZs operating without all the called for heat shields on the spar and ribs. Having these installed on mine helped, as did the fire sleeves on the fluid lines. One fire sleeve was damaged. If it had been unprotected, who knows?
Some possibilities are:
1) Excess vibration causing the break, although none was detected.
2) The front springs letting go caused the total load to be carried by the welded area.
3) Exhaust system rubbing on the cowling during engine torquing. I did leave adequate clearance and also had someone run-up the engine while I checked the clearance.
4) Simply age fatigue of the system.
I'm sure RAF will have their suggestions to go along with my article. If anyone has had a similar problem, please contact RAF or me at the address below.
Hope to be back in the air soon. The EZ is a great aircraft.
Good luck, fly safely,
308 Bayshore Dr.
Cape Coral, FL 33904 813-945-4824