"Even Lycoming concedes that there have been no failures with
these crankshafts. The FAA needs to do its homework and ensure that
there is compelling, risk-based data to support what will be an
expensive proposition for owners."
Source: Luis Gutierrez, AOPA director of
regulatory and certification policy, on the latest service bulletin
from Lycoming regarding crankshafts in its engines. AOPA is
concerned that the FAA is considering the issuance of an
airworthiness bulletin based off of SB 569 -- which calls for
replacement of over 5,000 crankshafts on engines ranging from the
O-360 to the IO-720.