Reference:
http://www.airweb.faa.gov/Regulatory...light=98-02-08

From the Preamble to AD 98-02-08:

SUPPLEMENTARY INFORMATION: On October 18, 1993, the Civil Aviation
Authority (CAA), which is the airworthiness authority of the United
Kingdom (UK), received a report that a Piper PA-28-161 aircraft, with a
Textron Lycoming O-320-D3G reciprocating engine installed, executed a
forced landing due to an engine crankshaft failure which caused the
propeller to separate from the aircraft. The cause of the crankshaft
failure was determined to be due to a high cycle fatigue mechanism that
had initiated from a number of corrosion pits in the crankshaft bore.
After the cracks had progressed through a substantial proportion of the
crankshaft section, the rate of advance had increased until the
remaining unseparated portion had failed as a result of overload. The
cracking occurred in high cycle fatigue and it had progressed over an
extended period of service. At the time of the accident the engine had
operated for 1,950 hours time in service (TIS) since overhaul and had
accumulated 4,429 hours total time since new over a period of 16 years.
In addition, the Federal Aviation Administration (FAA) has confirmed
that four other failures in the United States and 10 in foreign
countries were due to cracks initiating from corrosion pits in the
crankshaft bore on certain Textron Lycoming 320 and 360 reciprocating
engines with ratings of 160 horsepower or greater. Of the 10 failures
in foreign countries, four resulted in the propeller separating from
the aircraft inflight. Three of these four were from 1993 to 1996. The
FAA utilized metallurgical failure analysis reports and other
information to conclude that these failures were due to cracks
originating from corrosion pits. This condition, if not corrected,
could result in crankshaft failure, which can result in engine failure,
propeller separation, forced landing, and possible damage to the
aircraft.

Ref:
http://www.airweb.faa.gov/Regulatory...ght=2005-19-11

From the Preamble to AD 2005-19-11:
SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain Lycoming Engines (formerly Textron Lycoming) AEIO-360, IO-360,
O-360, LIO-360, LO-360, AEIO-540, IO-540, O-540, and TIO-540 series
reciprocating engines rated at 300 horsepower (HP) or lower. This AD
requires replacing certain crankshafts. This AD results from reports of
12 crankshaft failures in Lycoming 360 and 540 series engines rated at
300 HP or lower. We are issuing this AD to prevent failure of the
crankshaft, which could result in total engine power loss, in-flight
engine failure, and possible loss of the aircraft.

Dan