Talk:CFM International LEAP

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First Run

Needs Citation — Preceding unsigned comment added by Littlewill1166 (talk • contribs) 01:12, 22 July 2013 (UTC)[reply]

Yes, because the image of the 747-100 test aircraft with the test engine (LEAP 1-B), shows that it was tested on 4/3/2002(April 3, 2002). However the info box shows the first run on 6/13/2014(June 13, 2014) this makes no since.[Notice: I just realized at the typing of this that the engine in the 747 photo is NOT a CFM LEAP. It is a CFM56 engine (Says so on the caption when you click the image, "GE Aircraft Engines' B-747-100 with a CFM56 engine on the #2 pylon at Mojave") so this photo needs to be removed.]RaydenAG (talk) 14:25, 18 October 2019 (UTC)[reply]

The first run date was referenced since 2013. The photo illustrates "GE's 747-100 flying test bed", not leap testing.--Marc Lacoste (talk) 18:48, 18 October 2019 (UTC)[reply]

Leap-56 or Leap-X?

Which one is the new name? It needs to be consistent. —Preceding unsigned comment added by Mgw89 (talk • contribs) 21:15, 7 October 2009 (UTC)[reply]

Good catch - I missed the IP's changes back in July. From the newer sources, including the one you added, LEAP-X is the correct name. Thanks. - BilCat (talk) 00:42, 8 October 2009 (UTC)[reply]

LEAP-X is the technology demonstrator. Production engines go by LEAP-1C, -1B and -1A. So I will remove the X from the names. — Preceding unsigned comment added by 65.189.29.109 (talk) 00:45, 27 January 2012 (UTC)[reply]

Thrust Rating?

It says 18,000 to 50,000. Are they really designing an engine with that wide a marin for thrust ratings? Mgw89 (talk) 05:34, 21 January 2010 (UTC)[reply]

Overall Pressure Ratio?

It seems that 16:1 is low, seeing as the CFM56 is at 32, and the trend is increasing. —Preceding unsigned comment added by Mgw89 (talk • contribs) 07:24, 21 January 2010 (UTC)[reply]

Wrong direction of rotation!

The engine in the picture shows the wrong direction of rotation. Seen from the rear the engine has to turn in right-hand direction. However, the picture shows a left turning engine. —Preceding unsigned comment added by 95.88.97.209 (talk) 08:21, 8 May 2011 (UTC)[reply]

Why does it have to turn in that direction? More importantly, this is a manufacturer's image, not a user created one. -SidewinderX (talk) 17:58, 9 May 2011 (UTC)[reply]

All western aero engines are right turning. This is derived from the tradition of the propeller era and the accompanying piston engines. A pilot looked earlier always on a right turning air-screw (from his view seen). Exception: The GEnx engine with counter rotating shafts. The core engine is right turning and the fan is left turning like the large Rolls Royce engines (seen from the rear). The fan and the intermediate-pressure compressor of the RB211-Trent engines are left turning. Only the high-pressure compressor turns to the right. Official company photos are often falsified by the WEB designers, as they turn the picture. There are photographs of the LEAP-X (LEAP 56) in the WEB taken in a test-stand. There one can very good see how around the engine really turns. [See the manufacturers web-site here]. One should not trust into a picture which is not faked by oneself. Sorry for my poor Enlish. I am not a native speaker. —Preceding unsigned comment added by 95.88.97.209 (talk) 14:34, 13 May 2011 (UTC)[reply]

Is this fixed? Both pictures that I can see the vanes look like right handed to me. Gah4 (talk) 06:28, 9 December 2020 (UTC)[reply]

SFC at cruising speed?

What is the SFC (lb/h/lb) at cruising speed? — Preceding unsigned comment added by Fisch4Fun (talk • contribs) 01:18, 21 October 2014 (UTC)[reply]

The TSFC value added on 12/30/2017 lists the TSFC value as 0.42 lb/lbf/h, but I consider that value to be suspect. In Fundamentals of airliner performance, Part 6; The engine from 1/19/2015, Bjorn Fehrm of Leeham News lists SFC as 0.53-0.56 lb/lbf/hr at cruise for the LEAP. That value seems more credible to me, even though the total is from Leeham's simulations instead of an official source.D271l (talk) 22:49, 29 July 2019 (UTC)[reply]

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Troubled Introduction

"The troubled introduction of the PW1100G is making customers choose it and to power the A320neo " - I marked this as speculation but the original author has decided to remove the speculation mark. The cited article includes one point of view of one analyst, it is at best one opinion. Short of multiple citations by actual customers I think this is clearly a case of speculation. 85.159.97.4 (talk) 11:33, 19 March 2018 (UTC)[reply]

The PW GTF EIS is troublesome, see Pratt & Whitney PW1000G#Operational history with 17 serious references on troubles, and cites multiple airlines.--Marc Lacoste (talk) 14:40, 19 March 2018 (UTC)[reply]

Agree there have been troubles for it, there's objective evidence of that. What I disagree on is the the statement that the troubles are "making customers choose" one engine over another, based solely on one analyst's PoV. This is pure speculation (and is subjective) unless an actual customer (technically two or more) is quoted saying as such 85.159.97.4 (talk) 09:12, 30 March 2018 (UTC)[reply]

Did you read the ref?. PW market share of a320neo engine orders fell from 1/3 in 2016 to 1/10 in 2017. Factual not Bloomberg speculating.--Marc Lacoste (talk) 11:53, 30 March 2018 (UTC)[reply]

sigfigs

The Thrust ratings table seems to have five significant digits. Are they really known that accurately? Gah4 (talk) 06:30, 9 December 2020 (UTC)[reply]

You can check the ref.--Marc Lacoste (talk) 08:10, 9 December 2020 (UTC)[reply]

Yes they are there, but why? Are these measured or computed? One seems to be an exact conversion of 24000 lbf, and one I believe converts from kgf, but the rest I don't know about. The paper gives torques to three digits, so not excessive. Gah4 (talk) 09:24, 9 December 2020 (UTC)[reply]

Ask the EASA.--Marc Lacoste (talk) 12:25, 9 December 2020 (UTC)[reply]

MOS:LARGENUM recommends that overly precise numbers should be rounded unless there is a good reason not to. EASA are producing type certificates and technical documents, Wikipedia editors are producing a general encyclopedia. We have a similar problem in the aircraft specification template which is producing metre distance conversions to five decimal places, a coding editor is working on the problem. Nimbus (Cumulus nimbus floats by) 12:44, 9 December 2020 (UTC)[reply]

I put in a question on the EASA request page. The actual numbers in the document are integer daN. (That is dekanewton, I presume the usual SI unit for engine thrust.) Engine dimensions are integer mm. Minimum oil pressure seems to be nicely rounded to 1200hPa. Maximum exhaust temperature is 1013C (it doesn't round in F, either). Will have to wait and see what EASA says about it. Gah4 (talk) 18:02, 9 December 2020 (UTC)[reply]

I don't know which units the {{convert}} template is doing wrong, but it also seems to convert Mach to 5 digits. Default is supposed to match the input, but it doesn't. Gah4 (talk) 18:02, 9 December 2020 (UTC)[reply]

Mach number doesn't appear to be a supported unit? It would be difficult to convert to a speed unit as it changes with air density (altitude, temperature etc). Nimbus (Cumulus nimbus floats by) 18:27, 9 December 2020 (UTC)[reply]

{{convert|1.6|Mach}} Mach 1.6 (1,960 km/h; 1,220 mph) Even the people who work on {{convert}} don't know why. Gah4 (talk) 19:38, 9 December 2020 (UTC)[reply]

Altitude can be specified (in ft) : {{cvt|1.6|Mach|40000|km/h kn|0}} gives Mach 1.6 (1,700 km/h; 918 kn). Temperature would be even better, but hey.--Marc Lacoste (talk) 20:29, 9 December 2020 (UTC)[reply]

I suspect engine thrust also varies with air density and temperature. EASA reports take-off thrust and maximum continuous thrust, as noted to five digits. Airports are not all at sea level. Gah4 (talk) 19:43, 9 December 2020 (UTC)[reply]

Many variables affect thrust. Mach number can't be converted with a template, I'm surprised one exists. A Machmeter indicates the local Mach number as it is using dynamic pressure but it only reads in units of Mach, no airspeed, miles per hour, knots etc. Some flight computers can convert Mach number to true airspeed if the temperature is known.Nimbus (Cumulus nimbus floats by) 20:20, 9 December 2020 (UTC)[reply]

OK, reply from EASA: The ratings are declared by the engine TC holder in lbf, rounded to the nearest 10 lbf. In the EASA TCDS, the ratings are converted into daN, rounded to the nearest daN. For example, 32160 lbf gives 14305 daN using a factor of 0.4448. Seems to be one of those cases, probably not well described in sigfigs, where you really need an extra fractional digit, but round up to whole digits. Also, there is a need to reduce the problem of double rounding. Converted back to lbf, though, then has too many digits. Gah4 (talk) 19:51, 11 December 2020 (UTC)[reply]

Shame on EASA for this. You can change the ref to the FAA TCDS, where the native unit is lbf.--Marc Lacoste (talk) 05:51, 12 December 2020 (UTC)[reply]

I suppose, and if I find the FCC one I might to that. But I suppose I believe in what EASA did. First, it seems to be a calculated value. (I didn't post the whole reply.) If it is rounded to a multiple of 10 lbf, it could be considered to have an uncertainty of 5 lbf, as is implied by the digits. Multiplying by 0.4448 gives the product an uncertainty of about 2 daN. So four digits isn't enough, and five is too many. Sigfigs is an imperfect indicator of relative precision. The daN values might have been rounded to a multiple of 5, but that isn't really much better. I probably believe that four digits is enough, but isn't completely obvious. Gah4 (talk) 09:45, 12 December 2020 (UTC)[reply]

Using an info you got by email would be WP:OR, please avoid. Just get the FAA TCDS: E00089EN_Rev_7--08:04, 13 December 2020 (UTC)

Technically, WP:OR is allowed in talk, which is all I expected when I asked. As noted above, values can be rounded from those in the source, however having the FAA TCDS is nice. I notice, though, that the only difference is which values are in parentheses. There are some even worse cases in the FAA document, though not applicable here. The position of the center of gravity is given as 99.0 inch (which may or may not imply 0.1in resolution) converted to 2514.6mm, I suspect much more accurate than you can measure it. But yes, having the FAA document makes it easier to quote the actual value and convert to an accurate enough kN. (Not the daN used by EASA.) Gah4 (talk) 08:49, 13 December 2020 (UTC)[reply]

I might have noticed that the lbf values were all multiples of 10, but I got surprised by one that is 24000. Gah4 (talk) 08:49, 13 December 2020 (UTC)[reply]

Load Reduction Device

An article in the Seattle Times "" [After 2 serious 737 MAX engine incidents at Southwest, Boeing alerts pilots]https://www.seattletimes.com/business/boeing-aerospace/after-2-serious-737-max-engine-incidents-at-southwest-boeing-alerts-pilots/ describes an LRD, Load Reduction Device. It also (possibly mis?)quotes Boeing: "Boeing in a statement explained that the LRD does “not affect airplane handling, the crew cannot affect their operation, and no crew procedures change as a result of LRD activation.”" This doesn't make sense to me. If a large system connected to the engine failing doesn't result in changes to flight characteristics, including thrust, gyroscopic effects, fuel efficiency, etc. what's it doing on the aircraft?

Can anyone shed some light? 192.94.202.57 (talk) 22:51, 25 November 2024 (UTC)[reply]

From the readable information it's not a system but a frangible component in the engine spool (shaft) that mechanically disconnects the front fan (of a turbofan) if it looses a blade and becomes unbalanced (which could destroy the engine completely). It is clearly designed to help the aircrew by lessening the impact of the emergency and should improve the aircraft handling with an engine out. The problem appears to be that when this LRD has operated as designed engine oil has made its way into the cabin, the procedures have been amended to minimise this. Whether the crew should know about this feature or not is a forum subject. Nimbus (Cumulus nimbus floats by) 14:16, 26 November 2024 (UTC)[reply]

A better wikilink for what it is would be sacrificial part, it's a common concept in aircraft design, hydraulic pumps and generator drive shafts are designed to shear if they seize up, allowing the engine driving them to continue operating without problems, emergency systems exist to cope with the hydraulic/electrical failure. Nimbus (Cumulus nimbus floats by) 14:22, 26 November 2024 (UTC)[reply]