Air New Zealand completes biofuel test flight

A commercial aircraft has completed a test flight partially powered by second-generation biofuels, in a move to demonstrate the feasibility of using more sustainable fuels in existing aircraft.

An Air New Zealand Boeing 747-400 took off from Auckland International Airport for a two-hour flight over the Hauraki Gulf area using a blend of 50:50 jatropha and Jet A1 fuel to power one of the four Rolls-Royce RB211 engines.

The test flight was a joint initiative between Air New Zealand, Boeing, Rolls-Royce and Honeywell's UOP.

Air New Zealand chief executive officer Rob Fyfe said the flight was a milestone for the airline and commercial aviation: "Today we stand at the earliest stages of sustainable fuel development and an important moment in aviation history.

"Air New Zealand is proud to be playing its role in that journey by being the first to prove the viability of a second generation biofuel such as jatropha."

A programme of tests was planned for various altitudes and under a variety of operating conditions to measure the biofuel's performance through the engine and fuel systems.

Air New Zealand chief pilot Captain David Morgan said the results from the flight tests would provide the airline and its partners with invaluable data in helping jatropha to become a certified aviation fuel. "We undertook a wide variety of tests under normal and non-normal operating conditions, designed to test the biofuel to the fullest extent," he said.

The scheduled tests included:

* Take off: A full power take off, with throttles advanced as per normal operating conditions, establishing three-quarter power and then to full power.

* Climb: The aircraft climbs to 25,000ft. At an altitude of 20,000-25,000ft, the main fuel pump for engine one (the engine powered by the biofuel) was to be switched off. This was to test the lubricity of the fuel, ensuring the friction of the fuel does not slow down its flow to the engine.

* Cruise: Once cruising at 35,000ft the auto-throttle was to be switched off and the crew would manually set all engine controls, so the Engine Pressure Ratios (EPRs) and other engine performance parameters across all four engines could be checked for identical readings.

* Deceleration/acceleration: The crew were to control the fuel flow to the engine and measure the rate of change of the engine under these changing operating conditions.

* Descent: Engine one was to be shut down at 26,000ft with a windmilling restart at 300 knots. An engine shutdown would take place again at 18,000ft, this time with a starter-assisted relight at 220 knots.

* Simulated approach and go around: When the aircraft is at 11,000ft the autopilot was programmed to land on a runway "located" at 8,000ft and undertake a missed approach. This was to test the performance of the fuel under maximum thrust.

* Landing: The flight was completed with a normal landing, including the use of reverse thrust upon touchdown. The aircraft was then to taxi back to the hardstand, stop all engines and restart engine one by itself.

After the flight, Capt. Morgan commented: "The flight was notable for the lack of any surprises. Everything ran normally and as expected."

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