Shortly after carrying out a touch-and-go landing, at night on runway 29, a loud 'chuffing' sound was heard. Safety checks were begun, but the cockpit commenced to fill with smoke with no obvious sign of fire. Fresh air vents were closed and a close circuit was carried out for a normal landing. It was subsequently found that a number of exhaust pipe slip joint bolts were missing. One exhaust pipe had become detached and the escaping hot exhaust gases had burnt through the lower cowling. Safety Action As a result of the investigation into this and other similar occurrence (OASIS 9201731), the Bureau of Air Safety Investigation met with the Civil Aviation Authority Airworthiness (Powerplants) staff and discussed the apparent deficiencies with the exhaust clamping arrangements.
The CAA researched the available data and located a SOCATA Service Bulletin (SB), SB 10-073-78, which had been released in January 1994.
The CAA subsequently issued Aerospatiale (SOCATA) TB9, TB10 and TB20 Airworthiness Directives (ADs) AD/TB10/20, AD/TB10/21 and AD/TB20/27 effective 26 May 1994 mandating compliance with the manufacturers SB within 50 hours of time of service. This prompt action by the CAA, in full consultation with the Bureau of Air Safety Investigation, obviated the need for any formal safety output.