An airfoil having extended life due to reduction in stresses. A Hamming distance between any two scrambling sequences is half the length of a PSDU of the data packet or greater. The data components may be stored as a binary file or hierarchical file. A concavity in the expandable cuff collects body secretions, and other materials from the oral and nasal cavities andor gastro-intestinal reflux into the trachea, and the collected secretions are removed by aspiration through a lumen provided in the ventilation device.