A330: Rolls Royce Versus Pratt & Whitney

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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... 

Did you Miss the A330 training blogs? 

Here you go: 

Day 1: Understanding Airbus Flight Phases

Day 2: Differences between Boeing and Airbus

Day 3: Flying the Plane Fully Managed

Day 4: How does the Airbus Calculate Vapp?

Day 5: Go Around and the A330

Day 6: Getting too Slow with the A330

Enjoy the Journey!

XO Karlene