On July 1, 1989, a Champion 7GCBC (registration N7521F) was involved in an aviation accident near Ocean City, MD. Investigators recorded the probable cause as: LOSS OF ENGINE POWER FROM EXHAUST GAS LEAKAGE INTO THE CARBURETOR INLET, CAUSING ENGINE AIR STARVATION, AND MATERIAL FAILURE OF THE EXHAUST MANIFOLD. . This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot reported material failure of an exhaust pipe at the cylinder-to-muffler joint, leading to loss of engine power and ditching off a beach. No injuries were reported.
Incident Overview
A pilot flying a banner-towing aircraft over water along a beachfront experienced a progressive engine failure that culminated in a ditching. The aircraft was subsequently abandoned, and the pilot used a life preserver to reach shore.
Pilot Account
The pilot reported that he was flying at 200 feet MSL with the engine set at 2,250 RPM. He heard a faint sound from the engine and sensed that the muffler was separating. Attempting to climb, he found the engine would only develop 2,200 RPM at full throttle. He jettisoned the banner, and shortly thereafter the engine lost power. A burning smell filled the cabin, but no smoke was visible. The pilot ditched the aircraft and used a life preserver to float ashore.
Examination Findings
Post-accident examination revealed material failure of the exhaust pipe at the joint connecting the numbers three and four cylinder exhaust stack to the muffler. Additionally, soot and smoke discoloration were observed inside the carburetor inlet chamber.