Facts:

A.

A.a In a contract of 22 November 2002 amended on 5 February 2003, X.______ SA (hereafter: X.________) a company under Swiss law entrusted Y.________ (hereafter: Y.______), a company under American law with maintaining and servicing three aircrafts against a fee. The general conditions applicable to the contract included an arbitration clause.

A dispute arose in the performance of the contract and Y._______ initiated arbitral proceedings, which provided for the appointment of three neutral arbitrators. However, X.________ accepted to submit the dispute to a sole arbitrator.

In an award of 13 February 2008, arbitrator A._______ ordered X.________ to pay to Y.______ an amount of US$ 1,102,486.97 plus US$ 785,088.36 as interest on that amount as of 14 February 2008, as well as additional interest of 0.049315% by day from that date until payment.

A.b. On 1 April 2008, the United States District Court for the Central District of Illinois recognized the award and ordered X.________ to pay to Y.______ the aforesaid amounts and the additional interest.