The U.S. Navy’s next generation submarine hunter isn’t any good yet at hunting enemy submarines, according to recent Defense Department tests first reported on by Bloomberg.

A report filed by Michael Gilmore, chief of the Pentagon testing office, stated that the P-8A Poseidon exhibited flaws in the “plane’s radar performance, sensor integration and data transfer,” according to Bloomberg reporter Tony Capaccio, who received an early version of Gilmore’s report.

The U.S. Navy has spent about $35 billion on the P-8. The reported stated that the aircraft, which was built to replace the P-3 Orion, is not yet deployable, according to Gilmore’s report.

The Navy ran the P-8 through strenuous combat testing from September 2012 to March 2013. Results of those tests led Gilmore to conclude that the P-8 “is not effective for the intelligence, surveillance and reconnaissance mission and is not effective for wide area anti-submarine search,” according to the Bloomberg report.

U.S. officials outfitted a Boeing 737–800 with sensors capable of tracking submarines to produce the P-8. The Navy expected the P-8 to replace the P-3 and effectively track Chinese submarines.

The Navy plans to buy 113 of the P-8. So far, Boeing has delivered 13 of the aircraft.

Navy leaders told Bloomberg they are aware of the problems discovered in the P-8 and are working on software solutions to those problems.