flight crew member means a licensed crew member charged with duties essential to the operation of an aircraft during a flight duty period;
Floor seam sealer means any product designed and labeled exclusively for bonding, fusing, or sealing (coating) seams between adjoining rolls of installed flexible sheet flooring.
Filtering facepiece (dust mask) means a negative pressure particulate respirator with a filter as an integral part of the facepiece or with the entire facepiece composed of the filtering medium, not equipped with elastomeric sealing surfaces and adjustable straps.
Tight-fitting facepiece means a respiratory inlet covering that forms a complete seal with the face.
Loose-fitting facepiece means a respiratory inlet covering that is designed to form a partial seal with the face.