Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
From airplanes that have installed the Auxiliary Fuel Tank Optional Design Change (O-M) No. 42-056, three in-service failures of the auxiliary fuel tank venting system have been reported. These failures have led to the inability to supply the complete auxiliary fuel quantity to the main tanks and the collapse of the auxiliary tank. It is suspected that the vent lines were obstructed either by ice accretion under certain climatic conditions or by blockage of the vent valves because of fuel contaminants.
Undetected malfunctions of the venting system and damaged auxiliary fuel tanks may lead to a lower usable fuel quantity, subsequent fuelstarvation and/or fuel spillage into the nacelle.
The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.