Posted for "Zavatson, Christopher J \(US SSA\)" <Christopher.Zavatson@baesystems.com>:

 <<I believe the regulations require that the airworthiness certificate be
displayed in the cabin.>>
 This appears to be true.
 
 Section 91.203: Civil aircraft: Certifications required.
 (b) No person may operate a civil aircraft unless the airworthiness
certificate required by paragraph (a) of this section or a special flight
authorization issued under §91.715
<http://www8.landings.com/cgi-bin/get_file?pass=94711023&FAR/part_91/section_91.715.html>
 is displayed at the cabin or cockpit entrance so that it is legible to
passengers or crew.
 
 I like this part.
 <<so that it is legible to passengers or crew.>>
 This part is easy if the aircraft is a  737 and the certificate is posted on
the wall at eye level as you step on board.
 
 
 Chris Zavatson
 N91CZ
 360std
 www.N91CZ.com