Airworthiness Directives; Pilatus Aircraft Ltd., PC-6 Series Airplanes
We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) issued 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 the discovery of exfoliation corrosion in the fittings of some PC-6 airplanes. These fittings are installed exterior to the bottom skin of the wing skin. If not corrected, undetected corrosion in this area could lead to failure of the fitting and subsequent loss of control of the airplane. The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.
Airworthiness Directives; Bombardier Model DHC-8-400 Series Airplanes
The FAA proposes to adopt a new airworthiness directive (AD) for certain Bombardier Model DHC-8-400 series airplanes. This proposed AD would require inspecting to determine the manufacturer's date of certain V-band clamps on the engine exhaust shroud assembly, and doing related investigative/corrective actions if necessary. This proposed AD results from a report of a discrepancy found during a maintenance inspection on a V-band clamp located on the engine exhaust duct shroud. The clamp ends were touching (although the correct fastener torque had been applied), resulting in reduced clamp force on the flanges. We are proposing this AD to prevent vibration in the duct shroud and fretting of the V-band clamp and flanges, which could result in cracking of the flanges and consequent release of hot exhaust gases from the engine tailpipe and damage to adjacent structure. This situation could trigger the fire warning system and result in an in-flight emergency, such as the flightcrew shutting down the engine and activating the fire suppression system.