Here's as specific as I've found so far:
Prior to the merger, US Airways Group had 19 A320-family aircraft on firm order with Airbus scheduled for delivery in the years 2008 through 2010. US Airways Group also had ten A330-200 aircraft on firm order with Airbus scheduled for delivery in the years 2008 and 2009. In connection with the merger, on May 18, 2005, Airbus, US Airways Group, US Airways and AWA executed a Memorandum of Understanding that, in addition to providing for a $250 million line of credit from Airbus upon the satisfaction of various conditions precedent (including the completion of the merger and the emergence of US Airways from bankruptcy), provides for the rescheduling of US Airways’ A320-family and A330-200 delivery commitments, and an order for 20 A350 aircraft, for which Airbus has agreed to provide backstop financing for a substantial number of aircraft, subject to certain terms and conditions. Under the Airbus Memorandum of Understanding, US Airways’ A320-family aircraft will be rescheduled for delivery in 2009 and 2010, with US Airways’ A330-200 aircraft orders rescheduled for delivery in 2009 and 2010. The new A350 aircraft deliveries are currently scheduled to occur during the period 2011 through 2013. The Airbus MOU also modifies the cancellation rights on US Airways Group’s orders for the ten A330-200 aircraft provided that US Airways Group has met certain predelivery payment obligations under the A350 order. On September 27, 2005, upon emergence from bankruptcy and effective with the merger, US Airways Group, US Airways and AWA executed an A350 Purchase Agreement with AVSA S.A.R.L. and executed amendments to its existing Airbus purchase agreements to support and finalize the transactions called for in the Airbus MOU.
Also included was:
On September 27, 2005, in connection with the merger, AWA amended its A320 family aircraft purchase contract with AVSA S.A.R.L., to reschedule 11 aircraft deliveries from 2006 and 2007 to 2009. All other terms remained unchanged.
Jim
[Edit to add]
The 11 orders that HP had pre-merger were for 319/320's and nothing says whether that changed with the modified agreement or not. I would presume that Airbus would let us pick between the 319/320/321 within reason.