Bulgaria’s $100 Million F-16 Hits Trouble Again: Fuel Leak Sparks Concern

A new technical issue has been reported with one of the first F-16 Block 70 fighter jets delivered to Bulgaria earlier this year. Defense Minister Atanas Zapryanov confirmed the problem in a written response to "Revival" MP Tsoncho Ganev. The malfunction involves a fuel leak from one of the aircraft’s internal fuel tank compartments. According to Zapryanov, a representative of the U.S. manufacturer Lockheed Martin is scheduled to arrive in Bulgaria by the end of September to carry out the necessary repairs.

The minister explained that engineers and technicians from 3rd Fighter Air Base, together with American field representatives, had already completed significant diagnostic work. Their efforts resulted in a report identifying the probable cause of the leak. In parallel, consultations with the U.S. side have continued, and requests for the supply of additional consumables and spare parts have been submitted. Regulatory procedures classify the issue as a technical malfunction, requiring corrective measures before the aircraft can be returned to service.

This is not the first difficulty encountered with Bulgaria’s new fighter jets. When the first F-16 landed in the country in April, Air Force Commander Major General Nikolay Rusev announced that a deviation in the operation of one of its systems had been detected. At the time, he emphasized that the aircraft was not “broken” but required further inspection. The procedure for accepting the aircraft, he explained, is divided into two stages - technical and flight testing. Only once both are complete, and after successful flights with a Bulgarian pilot, can the aircraft be formally entered into service. The delay also explained why the much-anticipated appearance of the F-16 during the St. George’s Day military parade never materialized.

The issue sparked political controversy. GERB leader Boyko Borissov accused the government of purchasing a defective aircraft worth 100 million USD and demanded the immediate dismissal of Air Force chief Rusev. President Rumen Radev and Defense Minister Zapryanov defended the military leadership, noting that acceptance procedures were still ongoing. A circuit board was later replaced, and in June, Zapryanov assured that the aircraft was fully operational after completing both technical and aviation acceptance.

Despite this assurance, the latest development has once again drawn attention to the reliability of Bulgaria’s newly delivered fighters. For now, the two aircraft received so far - one single-seater and one two-seater - are not being used for combat duty to protect Bulgarian airspace. Bulgaria is scheduled to receive a total of eight aircraft under its 2019 contract by the end of 2025, though the Defense Ministry has declined to specify exact delivery dates, citing the complexity of planning transatlantic flights. A second batch of eight fighters is due by the end of 2027, which will give the Air Force its first complete F-16 Block 70 squadron.

The initial problems even attracted the attention of Brussels. Following the heated domestic debate in April, the European Commission stated that it was closely monitoring the situation. Commission spokesman Thomas Renier commented that any allegations of sabotage or foreign interference linked to the incident must be treated with seriousness and addressed through proper channels, but only on the basis of verified evidence.

For the time being, the F-16s remain in a testing and acceptance phase, with the Bulgarian Air Force stressing that no risks will be taken with pilots, crews, or equipment until the aircraft are declared fully ready for operational use.