What happened
On September 11, 2003, at 10:30, an instructor and a student departed on a navigation flight toward Lille-Lesquin in a CAF HR-200-120 B, registration F-GTZE. Shortly after takeoff, white smoke appeared inside the cabin. The instructor took control of the aircraft and performed an emergency landing.
Following the initial incident, maintenance personnel inspected the aircraft but were unable to replicate the phenomenon on the ground. Consequently, the instructor departed again at 11:15. During a subsequent takeoff into a headwind, the smoke reappeared, prompting a second landing. After the exhaust clamps were tightened, a third takeoff was attempted, this time accompanied by a mechanic. During the initial climb at approximately 500 feet, the crew detected the smell of exhaust gases and observed small amounts of smoke emerging from the heating vents, despite them being fully obstructed. The instructor immediately landed the aircraft at Merville. Shortly after the final landing, both the instructor and the mechanic experienced mild headaches.
The investigation
The investigation focused on the exhaust system to identify the source of the smoke and fumes. Technicians performed a dye penetrant inspection (ressuage) on the exhaust muffler. This inspection revealed a crack at the base of one of the two pipes that deliver hot gases into the right-side muffler.
Findings
- The investigation established that a crack in the exhaust muffler was the primary cause of the incident.
- The crack allowed exhaust gases to escape into the cabin via the heating vents.
- The aircraft and the exhaust muffler both had 1,900 flight hours since new.
- The exhaust system was subject to inspections every 100 flight hours.