FAA issues Emergency AD for recent 737s

Date:         09 Jan 98 00:50:44 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
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According to The Wall Street Journal, in articles on January 8 (p. B7)
and January 9 (p. A3), the FAA has issued an Emergency Airworthiness
Directive (AD) mandating inspections for 737s produced after September
20, 1995, based on preliminary findings from the wreckage of the
December 19, 1997 SilkAir 737 crash.

Investigators discovered that the right horizontal stabilizer may have
separated from the SilkAir aircraft prior to impact, and that two rows
of fasteners (26 in all) were missing from the leading edge of the right
horizontal stabilizer.  The fasteners may never have been installed.  In
addition, a hinge bolt from the right elevator was missing.

The AD requires immediate inspections to verify that the horizontal
stabilizers of 737s produced after September 20, 1995, are not missing
any fasteners.  While no cause has been determined for the SilkAir
crash, the emergency AD was issues as a precaution.  It directly affects
95 aircraft in the US registry; a total of 211 aircraft are affected
if/when regulators in other countries adopt the rule.

The WSJ articles also bring up the rudder problems suspected in the 1994
USAir 427 crash and the 1991 United 585 crash, but also notes that the
SilkAir crash occurred in very different circumstances.  The earlier WSJ
article says the rudder was designed prior to production of the SilkAir
aircraft, but the later article quotes a Boeing spokesman as saying the
SilkAir aircraft did not incorporate the modification.  (Either way, it's
probably not relevant to the crash.)

Karl Swartz	|Home	kls@chicago.com
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