Story ID: 
Four-blade prop for Metro II
By: Gordon Gilbert
Caption: Hartzell has introduced a four-bladed aluminum propeller conversion for the Fairchild Metro II that the company said reduces sound levels by 10 to 12 dBA, 
Word Count: 174
Hartzell has introduced a four-bladed aluminum propeller conversion for the Fairchild Metro II that the company said reduces sound levels by 10 to 12 dBA, providing a quieter cabin and lower external noise. The diameter of the new prop system is reduced by five inches from that of the original three-blade system. An “advanced airfoil configuration” was also applied to the new blades, said Hartzell. The new 97-in.-diameter blades are designed to reduce maintenance and operating costs “through the reduction in propeller-blade erosion from the shorter diameter and subsequently greater ground clearance,” said Hartzell. Also, the wide-chord design was specifically developed and tested to “provide more generous blade repair limits than the standard three-blade prop,” and the new blades eliminate the hub replacement compliance costs associated with AD 96-18-14.  Uninstalled list price for a kit is $47,500 per aircraft. In addition to a set of the new blades, the kit contains polished spinners and de-icing equipment. Hartzell’s warranty covers parts and labor for three years or 1,000 hr. There are nearly 200 Metro IIs in service.