5/10/2016

A320neo engines compared


Recently, in March, CFM revised their certification documentation for the LEAP-1A engine. There now is a G02 version and Addison Schonland from AirInsight already explained the differences between the original G01 certification standard and the G02.
The higher stated weight of the G02 is due to the fact that the EBU is now included in the weight. If we now look at the documentation of the competing PW1100G-JM engine from P&W we see that the EBU is included in it’s weight also.
The weight of the PW1100G-JM is 2857.6 kg or 6300 lbs.
The weight of the LEAP-1A (G02) is 3153 kg or 6936 lbs.
 

A stunning difference of 636 lbs or 1272 lbs per aircraft.
Now I guess that the nacelle of the LEAP-1A is a little bit lighter as the fan diameter is 3” smaller (78” versus 81” for the PW1100G-JM). So the difference at aircraft level would probably be more in the order of 1000 lbs.

When the A320neo was launched in December 2010 Airbus expected that the GTF powered version would be 100kg heavier than the LEAP-1A powered aircraft. So either P&W found a lot of weight saving opportunities or CFM underestimated their engine weight. To be fair, CFM later in 2011 introduced a seventh stage in the LPT and widened the fan Diameter from 75" to 78", so there are two changes that put more weight in the engine.

But 1000 lbs is no small number: it is equivalent to the weight of  4-5 passengers. Or in other words: if both engines would have the same fuel burn (according to John Leahy the LEAP engine is not yet at spec fuel burn), a PW1100G-JM powered aircraft could transport 4 to 5 passengers more by burning the same amount of fuel for the trip. So the questions is who in the end pays for the difference when you have a LEAP powered aircraft? The passenger with higher ticket prices? The airline through either higher fuelburn  or lower revenue? CFM through cost concessions at the maintenance side? Food for thougths...

12 comments:

  1. The weight data for the LEAP-1B was recently released: "Weight of the dry engine, including basic engine equipment, will not exceed 2780 kg".

    So, in a worst-case scenario for the MAX, the difference in dry engine weight for the 81-inch diameter PW1100G-JM on the A320neo and 6.4-inch diameter LEAP-1B on the 737MAX is just 77.6 kg (per engine).

    https://www.easa.europa.eu/system/files/dfu/EASA%20E%20115%20TCDS%20issue%201%20LEAP-1B_20160405_1.0.pdf

    Rgds
    OV-099

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  2. Addendum

    LEAP-1B fan diameter: 69.4"

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  3. "Or in other words: if both engines would have the same fuel burn (according to John Leahy the LEAP engine is not yet at spec fuel burn), a PW1100G-JM powered aircraft could transport 4 to 5 passengers more by burning the same amount of fuel for the trip."

    Is that always true?

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    Replies
    1. Have you examined the case of a 900 nautical mile mission at maximum passenger load and that is not limited by takeoff weight?

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    2. You tell me.

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    3. The LEAP powered aircraft would burn more fuel then as it is heavier. 1000lbs are worth about 0.65% fuel burn. So the LEAP powered aircraft would need 0.65% more fuel for the mission.

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    4. 0.65% fuel burn difference. What's the reality today?
      What about the 4 to 5 passenger difference? Gone?

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    5. Sorry, but I don't get it - is this a question? For the same fuel burn you can carry more pax on the GT powered aircraft. With the same payload you have more fuel burn with the LEAP powered aircraft. What is your problem?

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    6. 1000lb / 500kg Payload shortfall is not a small number. And it affects not only MTOW missions, but all TOW limited missions (e.g. Hot&High takeoff mission). Quite some operators chose the neo because of its better Hot&High payload capability compared to the classic/NG.

      According to AIRBUS info, 500kg transforms into 120nm Range on the neo(s).

      1000lb/500kg indeed results in ~0.6%-0.7% percent fuel burn on nearly every mission - for long legs the drawback is obvious - but also on short legs it hurts, because not only the fuel burnt is higher, but also the reserves you carry (which may double the fuel load on short legs).
      How severe is 0.6%-0.7%? Well, engine manufacturers usually take several years to develop a PIP which give 1% sfc improvement - and A/C manufacturers & operators are starving for these PIPs. So it must be worth something.

      On the cash side - hum, depends. Fuel cost is 30%-50% of COC (depending on the carrier), so .6% of 30% seems ridiculous. On the other hand, for airlines operating at the edge of profitability (which are quite some) it may matter.

      What I'm asking is: Isn't that shortfall already compensated for? IF they got the weight increase from the bigger fan (and additional LPT stage) - well - the fuel burn goes down, even if you take into account the fuel burn impact of the heavier engine.

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  4. The fuel burn depends on the actual sfc of both engines and other aerodynamic aspects that will be known only after the tests are completed at aircraft level. Weight is only one aspect. For the majority of meaningful missions the difference of 4 to 5 passengers mentioned in your article does not exist.

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