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  • Amiga500
    Rank 5 Registered User
    • Feb 2010
    • 2166

    Leap missing fuel burn targets

    From here [Other sources are backing this rumour up.]

    Problems for GE and Snecma? [and by extension, Boeing and Comac]

    Would that be the reason for Pratt bumping the GTF price list?

    You'd have to imagine this (if true) is good for Airbus, good for Embraer and good for Bombardier.



    [To put a 5% sfc differential in target, this is around the sfc improvement of the V2500 over its 25+ year life.]
  • Amiga500
    Rank 5 Registered User
    • Feb 2010
    • 2166

    #2
    More at Leeham...

    They are indicating 4.5% off target.

    Comment

    • chornedsnorkack
      Rank 5 Registered User
      • Jul 2005
      • 1108

      #3
      Originally posted by Amiga500 View Post
      More at Leeham...
      Subscription required.

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      • Amiga500
        Rank 5 Registered User
        • Feb 2010
        • 2166

        #4
        True (and a helluva expensive subscription it is too!), I did note the pertinent number below though.

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        • chornedsnorkack
          Rank 5 Registered User
          • Jul 2005
          • 1108

          #5
          So what is the range of 737MAX?

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          • Amiga500
            Rank 5 Registered User
            • Feb 2010
            • 2166

            #6
            Originally posted by chornedsnorkack View Post
            So what is the range of 737MAX?
            Dunno. I don't have access. I'm getting the info 2nd hand.

            Comment

            • Bmused55
              Aaahh Emu!
              • Oct 2003
              • 11136

              #7
              The improvements they've made in the aerodynamics should cancel out most if not all of this fuel burn issue.

              There will also undoubtedly be PIPs along down the line that will bring the engine to or past target. Much like the engines on the 787 and 748.
              Bmused55

              Keep thy airspeed up, less the earth come from below and smite thee.

              My Blog
              My Designs

              Comment

              • Amiga500
                Rank 5 Registered User
                • Feb 2010
                • 2166

                #8
                Originally posted by Bmused55 View Post
                The improvements they've made in the aerodynamics should cancel out most if not all of this fuel burn issue.
                Those improvements will have already been factored into guarantees given to customers.


                Originally posted by Bmused55 View Post
                There will also undoubtedly be PIPs along down the line that will bring the engine to or past target. Much like the engines on the 787 and 748.
                As I said, over its 25 year life, the sfc of the V2500 improved by about 5%. CFM will hopefully be able to beat that, but its not a forgone conclusion.

                Furthermore, often performance guarantees are given relative to the competition. P&W reckon they can add several percent improvement to the GTF by 2020 as they are so much further down the learning curve of the geared fan and don't have a very optimised thermal cycle, CFM by contrast are already optimising the thermal cycle (while not focussing overly on propulsive efficiency). Therefore, the PIPs would not only have to get performance to spec, but bridge to the performance upgrades installed on the GTF in the intervening time.


                Not good for the MAX or the C919.

                Comment

                • Bmused55
                  Aaahh Emu!
                  • Oct 2003
                  • 11136

                  #9
                  Well then, I guess Boeing should just shut up shop then, the expert has spoken!
                  Bmused55

                  Keep thy airspeed up, less the earth come from below and smite thee.

                  My Blog
                  My Designs

                  Comment

                  • Amiga500
                    Rank 5 Registered User
                    • Feb 2010
                    • 2166

                    #10
                    Originally posted by Bmused55 View Post
                    Well then, I guess Boeing should just shut up shop then, the expert has spoken!
                    Did I hit a sore point? Or just in a sensitive mood today?


                    Boeing will probably do alright-ish*. The slot constraints on A320 will see to that. But their SA market share would drop, maybe significantly.
                    For GE and Snecma it could be a bit of a disaster - they could be paying out penalties for a good few years.
                    Not too many are going to buy the C919 for performance reasons, so it is kinda irrelevant.


                    *But they may be getting forced into a corner on two things. 1. Invest more money and engineering time than envisaged into airframe improvements to make up the shortfall. 2. Move the timeframe for NSA forward.
                    Neither are ideal.

                    Comment

                    • chornedsnorkack
                      Rank 5 Registered User
                      • Jul 2005
                      • 1108

                      #11
                      Originally posted by Amiga500 View Post
                      Did I hit a sore point? Or just in a sensitive mood today?


                      Boeing will probably do alright-ish*. The slot constraints on A320 will see to that. But their SA market share would drop, maybe significantly.
                      For GE and Snecma it could be a bit of a disaster - they could be paying out penalties for a good few years.
                      Not too many are going to buy the C919 for performance reasons, so it is kinda irrelevant.
                      Can any disappointed 737MAX customers or would-be customers buy CS300 instead? Like the airlines for whom 737MAX was slightly too much plane, but A320 far too much?

                      Comment

                      • Amiga500
                        Rank 5 Registered User
                        • Feb 2010
                        • 2166

                        #12
                        Originally posted by chornedsnorkack View Post
                        Can any disappointed 737MAX customers or would-be customers buy CS300 instead? Like the airlines for whom 737MAX was slightly too much plane, but A320 far too much?
                        No idea. I guess that would be a contractual matter between them and Boeing.

                        Assuming the performance issues are for real, then I suppose considerations would include:
                        - What clauses exist on performance guarantees/penalties?
                        - Did they make firm orders, letters of intent or some other executive-speak thing that doesn't really mean much but can be included as an "order"?
                        - Just how bad is (if any) the performance shortfall to guarantees?
                        - Is there a mitigation plan in place after the aircraft is delivered? What happens if this plan doesn't meet further guarantees?

                        Comment

                        • Amiga500
                          Rank 5 Registered User
                          • Feb 2010
                          • 2166

                          #13
                          More here:

                          http://airwaysnews.com/blog/2015/04/...oeing-737-max/

                          They raise a point I hadn't considered.

                          If MAX+LEAP really is 5% off the pace of the A320NEO+GTF, and P&W get a 3% PIP prior to 2019, that will force Boeing's hand with regards their muted middle-of-market concept.

                          i.e. If its a twin-aisle, they'd have to pretty much scrap it and focus on NSA instead, with NSA also covering longer ranged missions.
                          Last edited by Amiga500; 28th April 2015, 13:08.

                          Comment

                          • chornedsnorkack
                            Rank 5 Registered User
                            • Jul 2005
                            • 1108

                            #14
                            If 737MAX is squeezed between CS300 and A320NEO, both of which have efficient GTF engines, how can Boeing respond?

                            Comment

                            • Amiga500
                              Rank 5 Registered User
                              • Feb 2010
                              • 2166

                              #15
                              Good news for CFM (and by extension, Boeing and Comac):

                              http://leehamnews.com/2015/05/07/cfm...light-testing/

                              “When we build development engines they are heavily instrumented and built to accomplish extreme test conditions and durability,” he explains. “They are intentionally deteriorated and have open clearances because they are built for the ‘corner point’ in the test effort. We do pre-test predictions and we are within 0.5% of every one, so we are right on track. We fully expect to be right on our commitment as we enter into service.”
                              Last week, we received a clarifying explanation that appears to track with the Aviation Week article and the excerpt above. We were told that the 4%-5% number came from a test stand test in which the tolerances of the engine were much looser than the optimal performance engine. The clearances, we were told, were not to specification–and the result was the 4%-5%.

                              Comment

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