CN235 FTB Completes First J2.4 Bioavtur Test Flight, Engines Reported Normal

Bandung — A CN235-220 Flying Test Bed (FTB) aircraft operated by PT Dirgantara Indonesia made its first test flight using J2.4 bioavtur on 9 September 2021. Indonesia’s Ministry of Energy and Mineral Resources (ESDM) said the flight lasted one hour and 20 minutes at 10,000 feet around Sukabumi and Pelabuhan Ratu. The right engine used bioavtur while the left used conventional Jet A-1 fuel. Test pilot Captain Adi Budi Atmoko reported normal engine parameters throughout the test sequence and no engine surge or flameout.

This was a test on one aircraft, not an approval for fleet-wide use. CN235-220 FTB project manager Eko Budi Santoso said an analysis of bioavtur fuel efficiency had not yet been carried out. The reported completion of the first flight therefore should not be read as a fuel-savings result.

What the crew tested in the air

According to ESDM’s 9 September statement, the crew started both engines, taxied and took off for the Sukabumi test area. Adi said they tested engine parameters from flight idle to maximum cruise power, as well as acceleration and deceleration. He described the data from the two engines as relatively similar during these checks: the left tank held Jet A-1 and the right held bioavtur. The test sequence also included shutting down an engine and restarting it; Adi reported that it started again and stabilised.

Eko said the flight at 10,000 feet ran for one hour and 20 minutes without an engine disturbance. Adi described the day’s flight-test sequence as 100% completed, with the results within normal limits. That figure refers to completion of the reported test, not to a certification outcome, approval for all aircraft or a measured improvement in efficiency.

Ground tests preceded the first flight

Airspace Review reported that the CN235 FTB had undergone a ground test at PT Dirgantara Indonesia’s Bandung facilities on 6 September. According to the publication, the 20-minute ground test was conducted three times under varying conditions, including different times of day. Engine power was varied from low to maximum and back. Those ground checks preceded the aircraft’s first flight with the fuel on 9 September.

Airspace Review described the J2.4 fuel used in this test as containing 2.4% refined, bleached and degummed palm kernel oil (RBDPKO), with a catalyst. That percentage describes the composition reported by the publication; it is not a measured emissions reduction or fuel-efficiency gain from the flight. Neither of the two reports cited here provides a measured efficiency or emissions result from this first flight.

Further tests remained on the agenda

ESDM reported Eko’s plan for another flight at 16,000 feet after the initial 10,000-foot test. Airspace Review also reported a planned subsequent flight on 15 September and said ground- and flight-test data would inform the Directorate of Airworthiness and Aircraft Operations and the Indonesian Military Airworthiness Authority. As of the reports dated 9 September, these were plans and intended uses of data, not completed further flights or regulatory decisions.

The finding reported so far is narrower: this initial CN235 FTB flight completed its test sequence with normal engine parameters and no reported surge or flameout. Additional testing and assessment of the data remained distinct from this first-flight result. A successful individual test flight by itself does not establish that J2.4 is cleared for general aviation use.