Libyan Airlines and lessor ILFC have each converted their orders for the Airbus A350-800 to the larger -900, with Libyan Airlines ordering an additional pair of -900s under its revised agreement.
Conversion of the 10 aircraft takes the backlog for the -800 down to 46.
Airbus's latest order and delivery data, covering the month of January 2014, reveals the switch by the two -800 customers.
ILFC had been a customer for the first iteration of the A350, but amended its agreement in 2007 following the launch of the A350 XWB family. It placed orders for 12 -800s and eight -900s but subsequently converted all but six -800s to the larger variant.
The latest customer data from the airframer shows that ILFC has switched these six remaining aircraft and all 20 are confirmed as -900s.
Libyan Airlines placed its order for four A350-800s in January 2008.
Airbus says the carrier placed a "repeat order" for the A350 last month, with a deal for two -900s, but the backlog data shows that it has also converted all four -800s and, as a result, has six -900s on order.
The airframer ended January 2014 with firm orders for 10 aircraft, comprising the Libyan A350s and eight A320-family jets. But its net figure stood at five aircraft following cancellation of three A319s and two A320s.
Airbus delivered 39 aircraft during the month including its first A380 of the year to British Airways.