For Two Weeks I wrote Blogs about A330. Today I received an email that said,
"Love your stuff on the A330 but you MUST remind your fans that you fly PW-powererd A330s. Because RR-powered A330s have a completely different TO/GA procedure on T/O which is known as MEASTO and on older versions as KOZ. MEASTO rectifies all the anomalies and asymmetry with FADEC JC3 software. Remember be a maestro with MEASTO!"
What in the heck is MEASO and KOZ?
MEASTO: A330 RR Trent 700 series, and is the latest FADEC software
KOZ: A320, A330, A340 for IAE 2500. RR Trent 500, RR Trent 700
FADEC C3J Software on A340 aircraft with CFM 56-5C Engines
Modified Engine Acceleration Schedule for TakeOff
– High crosswind, tailwind or intake turbulence: Increase risk of fan stall
– The Fan stall risk zone is more significant at low speed.
– Engines automatically react against fan stall.
- If a stall occurs: Engine power is reduced.
– Automatic and progressive thrust setting during takeoff:
- Engine acceleration is controlled by a predefined EPR/second rate,
- Function only active during the low speed phase of takeoff (speed < 50 knots)
- Engines not fitted with this function, acceleration law had to be reproduced by the crew.
– It takes about 10 additional seconds to reach takeoff power.
– For all flight conditions, takeoff thrust is achieved before 80 knots.
– This function is only available on ground, and with forward thrust:
- Also available for ground maintenance tasks.
KOZ is the older version (Keep Out of Zone).
The KOZ (Keep Out Zone) implemented on:
· A330 Rolls Royce (Trent 700)
· A320/A319/A321 IAE (V2500 A5 series)
· A340-500/600 Rolls Royce (Trent 500)
To avoid fan flutter, the FADEC prevents stabilization in a certain EPR (N1) zone, depending on the engine type.
· For example, the KOZ for RR Trent 700 is between:
– 1.16 to 1.28 EPR
– The N1 interval changes, based on the temperature of the day.
· The max upper and min lower limit are: 51.4% and 73.6%
The KOZ is active when:
– Aircraft on ground, and
– Low aircraft speed (M<0.15 or <80 knots), and
– Forward thrust.
During Engine Acceleration:
· When the thrust lever is advanced through the KOZ, there is a pause in the EPR command at the lower EPR command limit.
· The EPR command will remain at the lower command limit, until the thrust lever is advanced such that the corresponding EPR command exceeds the upper EPR command limit.
· Then, engine power will continue to increase with the thrust lever position.
To avoid cracking the fan blade root due to fan flutter, the FADEC prevents stabilization in a certain EPR (N1) zone.
· This automatic KOZ replaces the manual KOZ, applied by crews, to avoid operation in a specific fan speed range.
· In EPR mode, KOZ changes are based on the daily temperature.
· In N1, the Keep Out Zone is between 61% to approx. 74
KOZ is transparent to the crew:
· Not felt in the takeoff procedure
· Low probability to reach this value during taxi
There you have it. KOZ and MEASTO. I'm wondering why anyone would order RR engines...
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Enjoy the Journey!