Re: New US Air 427 Hypothesis

From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
Date:         29 Sep 94 00:15:38 
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>Do you think they might be able to link these two crashes?  Most
>people have discounted the link because the current best theory for
>the COS crash assumes that the mountain weather patterns were involved.

A while after UA 585 went down, I talked to someone from United who
said some people at the airline thought rudder problems were a more
likely explanation for the crash.  Apparently the rudder actuator on
a 737-200 Advanced is significantly different than the non-Advanced
version, and United had had some problems with the Advanced rudders,
possibly due to being a different mechanism than most of the fleet.

To explain a bit, the accident aircraft (N999UA) was a 737-291
Advanced, one of 25 similar aircraft (two were -2A1 Advanced models)
acquired from Frontier in the late 1980s.  These were in addition to
80 737-222 (non-Advanced) models which United purchased new from
Boeing, of which around 45 are still in service.  Thus, most of the
experience at United was with the non-Advanced models.  (I'm ignoring
the 737-322 fleet here; they're substantially different, and at the
time were still pretty new.)

That's just a rumor of a rumor, so treat is as such, though I'd love
to hear more about the mechanisms from anyone who has actually worked
on both 737-200 flavors.  (Maybe at Delta? 8-) )

Karl Swartz	|INet
1-415/854-3409	|UUCP	uunet!decwrl!ditka!kls
		|Snail	2144 Sand Hill Rd., Menlo Park CA 94025, USA
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