How to identify jet engines: CFM56, LEAP, V2500, PW1000G, Trent, GE90 and GEnx

For many spotters, the engines are the most beautiful detail on an aircraft – and the most useful. If you can identify jet engines, you don’t just tell generations like the A320neo and ceo apart with confidence, you also distinguish variants that otherwise look almost identical. On top of that, a handful of types let airlines choose between two or three engines, and these very combinations make some sightings interesting in the first place. This guide introduces the seven most important engine families in commercial aviation – CFM56, LEAP, V2500, PW1000G, Trent, GE90 and GEnx – and shows how to recognize them from the fence.

The short answer: type first, then engine

The most important trick is not a visual feature but knowledge: Most aircraft types fly with just a single engine. A Boeing 737 MAX 8 always has the LEAP-1B, an A350-900 always the Trent XWB, a 777-300ER always the GE90-115B. Once you have identified the type, you know the engine in these cases too.

It only gets exciting where airlines can choose – on the A320 family, the A330ceo, the early 777s, the 787 and the A380. Here, nacelle shape, fan size, blade count and details like chevrons help you. And when the eye reaches its limits, the registration in the fleet database settles the question.

Who builds the engines?

Behind the big names there are often joint ventures. CFM International is owned half by General Electric and half by the French group Safran and builds the CFM56 and LEAP. The V2500 comes from International Aero Engines, a consortium in which Pratt & Whitney, the Japanese Aero Engines Corporation and MTU Aero Engines hold stakes; Rolls-Royce was among the founders but left in 2012. The PW1000G geared turbofan is Pratt & Whitney’s responsibility, the Trent family is Rolls-Royce’s alone, and the GE90, GEnx and GE9X belong to General Electric. The Engine Alliance, a joint venture of GE and Pratt & Whitney, supplies the GP7200, the alternative to the Trent 900 on the A380.

Which type flies with which engine?

This overview is your most important tool. It shows where the engine is fixed and where you need to look more closely.

Aircraft type	Engine(s)	Choice?
Boeing 737 Classic (-300/-400/-500)	CFM56-3	no
Boeing 737 NG (-600 to -900ER)	CFM56-7B	no
Boeing 737 MAX	CFM LEAP-1B	no
A320ceo family	CFM56-5A/-5B or IAE V2500	yes
A320neo family	CFM LEAP-1A or PW1100G-JM	yes
Airbus A220	PW1500G	no
Embraer E190-E2 / E195-E2	PW1900G	no
A340-200/-300	CFM56-5C	no
A340-500/-600	Trent 500	no
A330ceo	GE CF6-80E1, PW4000 or Trent 700	yes
A330neo	Trent 7000	no
A350	Trent XWB	no
A380	Trent 900 or Engine Alliance GP7200	yes
777-200/-200ER/-300	GE90, PW4000 or Trent 800	yes
777-300ER/-200LR/777F	GE90-115B	no
777X	GE9X	no
787	GEnx-1B or Trent 1000	yes
747-8	GEnx-2B	no

How to tell the types themselves apart is explained in the guides How to tell Boeing 737 Original, Classic, NG and MAX apart, A330 or A340 and Telling the Boeing 777 and 787 apart.

CFM56: the classic with the flat bottom

The CFM56 is one of the most-built jet engines of all time – by mid-2018, CFM had delivered more than 32,000 units. The first test-stand run took place in 1974. As a spotter, three variants matter to you:

• CFM56-3 on the 737 Classic: Because the 737 sits very low, the fan had to stay small at roughly 1.52 meters, and CFM moved the accessory gearbox from the underside to the side. The result: The inlet is flattened at the bottom. This oval, “flat” nacelle is the hallmark of the Classic generation.
• CFM56-7B on the 737 NG: Fan roughly 1.55 meters, the nacelle is also flattened at the bottom but looks rounder and more modern. On the 737-800 you see this engine every day at almost every airport.
• CFM56-5 on Airbus: The -5A and -5B versions power the A320ceo, the more powerful -5C the four-engine A340-200 and A340-300. On the A320, the inlet is round, and behind the short fan cowl the narrower engine core with its exhaust cone peeks out.

You know the early military and retrofit version, the CFM56-2, from the KC-135R and from re-engined DC-8 Super 70s – today more of a rarity for military spotters.

LEAP: the big successor

With the LEAP, CFM built the next generation. The fan consists of 18 wide, curved blades made of woven composite – significantly fewer and significantly wider than on the CFM56. There are three versions, the third for the COMAC C919:

Variant	Aircraft	Fan diameter (approx.)	Entry into service
LEAP-1A	A320neo family	1.98 m	2016
LEAP-1B	Boeing 737 MAX	1.76 m	2017
LEAP-1C	COMAC C919	1.96 m	2023

On the A320neo, the LEAP-1A looks hefty and perfectly round. On the 737 MAX, Boeing placed the engine higher and further forward and lengthened the nose gear by roughly 20 centimeters so that the larger fan fits under the wing. The strongest feature, though, is the serrated trailing edge of the nacelle: The chevrons of the LEAP-1B set a MAX apart from a 737 NG at a glance. The round shape of the inlet is a second clue – the flat bottom of the predecessors is gone.

IAE V2500: the slim alternative

The V2500 first ran in 1987 and is the competitor of the CFM56-5 on the A320ceo family. It also powers the MD-90 and the Embraer C-390 military transport. With a fan of roughly 1.61 meters, it is slightly smaller than the CFM56-5.

Visually, you recognize it by the long, closed nacelle: It extends further back, and the engine core doesn’t visibly stick out as on the CFM56-5. The whole nacelle therefore looks slim and cigar-shaped. How to read generation and wingtips on the A320 as well is covered in the guide How to tell the A320neo from the ceo.

PW1000G: the geared turbofan

In the Pratt & Whitney PW1000G, a gearbox sits between the fan and the low-pressure shaft – the principle existed before in smaller engines, but in this thrust class it is new. The reduction ratio of roughly 3:1 lets the fan turn more slowly than the turbine. MTU Aero Engines from Munich participates in the program.

Variant	Aircraft	Fan diameter (approx.)	Fan blades
PW1100G-JM	A320neo family	2.06 m	20
PW1500G	Airbus A220	1.85 m	18
PW1900G	Embraer E190-E2 / E195-E2	1.85 m	18

On the A220-100, the A220-300, the E190-E2 and the E195-E2, the geared turbofan is the only powerplant – no guessing needed here. On the A320neo it competes with the LEAP-1A, and the two are visually hard to tell apart. The blade count is the cleanest feature: 20 on the PW1100G, 18 on the LEAP-1A. For that, though, you need a sharp photo from the front. How to separate first- and second-generation E-Jets is shown in the guide Telling Embraer E-Jets apart.

Rolls-Royce Trent: three shafts, many variants

The Trent family is the backbone of Rolls-Royce in widebody aviation. All variants work with three concentric shafts – a legacy of the RB211. You can’t see the shafts from outside, of course. For spotters, what matters most is which variant sits on which type:

Variant	Aircraft	Fan diameter (approx.)	Choice on the type?
Trent 700	A330ceo	2.47 m	one of three options
Trent 800	777-200/-200ER/-300	2.80 m	one of three options
Trent 500	A340-500/-600	2.47 m	only powerplant
Trent 900	A380	2.95 m	alternative to the GP7200
Trent 1000	Boeing 787	2.84 m	alternative to the GEnx-1B
Trent XWB	A350	3.00 m	only powerplant
Trent 7000	A330neo	2.84 m	only powerplant

On the A330-900, you recognize the Trent 7000 by its size alone: The nacelles are noticeably more massive than on the A330ceo, and the aircraft additionally carries new, larger wingtips. On the A380, by contrast, telling the Trent 900 from the GP7200 is visually difficult – the fleet database helps here. How to separate the A350 and 787, both of which can fly with a Trent, is shown in A350 or Boeing 787.

GE90: the giant on the 777

The GE90 entered service in 1995 with British Airways on the 777 and, with its 22 wide composite blades, was ahead of its time. The early versions have a fan of roughly 3.1 meters. The GE90-115B for the 777-300ER, 777-200LR and 777F comes in at roughly 3.25 meters – not far from the fuselage diameter of a 737.

For you, this means: Every 777-300ER, every 777-200LR and every 777F carries this engine, because GE won the contract as sole supplier for these models. On the older 777-200 and 777-200ER, a closer look is worthwhile: Pratt & Whitney PW4000 or Rolls-Royce Trent 800 engines may hang there too. You recognize the GE90 by the most massive inlet of the three and by the wide, strongly curved fan blades, which look like a propeller with few blades in photos from the front.

The successor, the GE9X for the Boeing 777-9, goes one better: roughly 3.40 meters of fan diameter and only 16 blades. It was developed exclusively for the 777X.

GEnx: the chevron nacelles of the 787

The GEnx is in a sense the little brother of the GE90, also with composite blades, 18 of them here. There are two versions:

• GEnx-1B on the Boeing 787: Fan roughly 2.82 meters. The nacelle carries the distinctive chevrons on the trailing edge that shape the look of the 787-9 and the 787-8.
• GEnx-2B on the Boeing 747-8: Fan roughly 2.66 meters, the only powerplant of the 747-8 in passenger and freighter versions. Here too the nacelle trailing edge is serrated, but the four engines and the hump make the 747-8 unmistakable anyway. The 747-8F brought the engine into airline service at the end of 2011.

On the 787, the GEnx-1B competes with the Trent 1000, and both nacelles carry chevrons. Telling them apart is therefore demanding. Some airlines or manufacturers label the nacelles with the engine’s name, but that is not a rule. It only becomes reliable with the registration. You can find more on the 747 variants in How to identify the Boeing 747-100 to 747-8.

The features at a glance

When you’re standing at the fence, it’s best to run through these features – from coarsest to finest:

Fan blades compared

Engine	Fan blades	Effect in the photo
CFM56-5A/-5B	36	dense ring of narrow blades
CFM56-7B	24	narrow blades, less dense
GE90	22	wide, strongly curved composite blades
PW1100G	20	wide blades
LEAP, GEnx, PW1500G/PW1900G	18	wide, curved blades
GE9X	16	very wide blades

Common mix-ups

737 NG or MAX on approach

From below, both generations look similar, but the chevrons of the LEAP-1B and the round inlet give away the MAX. Also watch the wingtips – the MAX carries the two-part AT winglets that you get to know in the guide Winglets, sharklets, split scimitar and raked wingtips.

CFM56-5 or V2500 on the A320ceo

The nacelle length helps here: On the CFM56-5, the fan cowl ends early and the core peeks out, while on the V2500 the closed nacelle reaches far back. In the model designation, a 1 in second position stands for the CFM56 (such as A320-214), a 3 for the V2500 (such as A320-232).

GEnx-1B or Trent 1000 on the 787

Both have chevrons, similar size and a similar nacelle. Telling them apart by eye alone rarely works reliably. Use the registration and the fleet database, as described in the guide Tracking an aircraft by registration. If the registration in your photo is hard to read, Finding an unreadable registration helps.

Where you see many engines at once

The biggest selection is at the hubs with lots of long-haul traffic. At Frankfurt Airport, from the Zeppelinheim viewing platform you see A350s, 787s, 777s, A330s and 747-8s in turn – and with them the Trent XWB, GEnx, GE90 and Trent 7000 in a single afternoon. At Munich Airport, the visitors’ hill offers a good view of taxiing aircraft whose nacelles you can study in peace.

If you want not just to see engines but to hear them too: The differences in sound between old and new generations are clear. You find tips in the guide Recording engine sound. And how type codes in live maps are structured is explained in ICAO type codes explained.

Conclusion

Engines are the detail where generations and variants show most clearly. The flat nacelle of the 737 NG, the chevrons of the 787, the huge inlet of the GE90 – after a few sessions at the fence, you recognize these features without thinking. For getting started with type identification as a whole, the guide Identifying aircraft types for beginners is worth a read.