Lockheed Martin [LMT] yesterday said it has delivered its third of 14 planned upgraded P-3 Orion maritime patrol aircraft to Customs and Border Protection (CBP).

Lockheed Martin is upgrading most of CBP’s fleet of P-3s with new structures, which include a new metal allow that is five times more corrosion resistant than the original material, to reduce maintenance costs. The mid-life upgrade to the aircraft adds more than 20 years of operational use.

The first upgraded P-3 was delivered in July 2010 and the second aircraft in April 2011.

CBP operates a fleet of 16 P-3s. The last of the 14 that will be upgraded by Lockheed Martin will occur in 2015.