Chevrons are the saw-tooth serrations on an engine nacelle’s trailing edge, and Boeing is the only major manufacturer to have put them on multiple commercial programs: the 747-8 (now out of production), the 787 Dreamliner, and the 737 MAX. Boeing’s newest widebody, the 777X, omits them.
No rival adopted chevrons at scale, and no manufacturer has publicly confirmed a phase-out. The pattern is an inference from the production record, not a stated corporate decision.
The headline writes itself: with the 747-8 out of production, the 787 Dreamliner is the last aircraft still being built with chevrons. It’s clean, it’s dramatic, and it’s wrong.
The 737 MAX is still rolling off the line in Renton, and its CFM LEAP-1B engines carry the same serrated nacelle edges. So the “only aircraft” framing collapses on contact with the production record.
What survives is a stranger and more interesting question. Why did Boeing’s newest widebody, the 777X, drop a design the company patented, applied across three programs, and never sold to anyone else?
That’s the real subject here. Not a eulogy for a failed gimmick — chevrons shipped across three Boeing programs, which is hardly a flop — but the quiet disappearance of a design signature from the aircraft meant to carry it forward. And the honest answer, at least from the public record, is that nobody has said why.
What chevrons actually are
On the trailing edge of an engine nacelle — the pod around the fan — chevrons take the form of serrated, saw-tooth extensions. They look aggressive, almost decorative. They aren’t.
Their job is to break up and mix the airflow where the engine’s fast-moving exhaust meets the slower freestream air. That mixing lowers the noise the engine radiates at takeoff and landing, the two phases where airports and their neighbors care most. It’s a mechanical fix to an acoustic problem, and it’s visible from a window seat if you know where to look.
The production record: who has them, who doesn’t
Boeing is the outlier here, and not in the way the headline suggests. It’s the only major manufacturer to have brought chevrons to multiple commercial jet programs, and it did so after securing patents on the design.
The 747-8 carried them on its GEnx-2B engines. The program closed after 155 aircraft were built, the last a freighter handed to Atlas Air on January 31, 2023. The 787 Dreamliner carries them on both engine options — the GE GEnx and the Rolls-Royce Trent 1000. The 737 MAX carries them on the CFM LEAP-1B.
Then there’s the 777X. Boeing’s newest widebody, still in flight test, flies behind the GE9X — and the GE9X has a smooth nacelle. No serrations. The first clean departure from the design since it debuted.
| Aircraft program | Engine option(s) | Chevron present | Production status |
|---|---|---|---|
| 747-8 | GEnx-2B | Yes | Ended; final delivery January 31, 2023 |
| 787 Dreamliner | GEnx or Rolls-Royce Trent 1000 | Yes | In production |
| 737 MAX | CFM LEAP-1B | Yes | In production |
| 777X | GE9X | No | In development and flight test; production entry date not verified in retrieved official material |
| 777-300ER | GE90-115B | Unverified from retrieved official specification | Ended; exact end date not verified in retrieved official material |
| 767 | CF6-80C2, PW4000 or CF6-80A | Unverified from retrieved official specification | In production as a freighter; exact current production status wording not verified in retrieved official material |
| Airbus A350 | Rolls-Royce Trent XWB | Unverified from retrieved official specification | In production |
| Airbus A320neo | CFM LEAP-1A or Pratt & Whitney PW1100G-JM | Unverified from retrieved official specification | In production |
| Airbus A330neo | Rolls-Royce Trent 7000 | Unverified from retrieved official specification | In production |
| COMAC C919 | CFM LEAP-1C | Unverified from retrieved official specification | In production |
| Source: The Boeing Company; GE Aerospace; Google Patents; supplied research record | |||
Superdeals cover departures from North America, Europe and Australia.
Flight deals most people never see
Air Traveler Club monitors thousands of routes for pricing anomalies that traditional search engines miss. With ATC Superdeals members save up to 80% on each flight vs. regular fares.
Too good to be true? Check it out yourself. It's free.
Delivered weekly. Unsubscribe anytime.
The patent behind Boeing’s design signature
The design traces to a Boeing patent — U.S. Patent 6,612,106 B2 — covering a segmented mixing device built to reduce jet-engine exhaust noise. Google Patents records a May 5, 2000 priority date, a March 30, 2001 filing, and a September 2, 2003 publication. The patent has since expired.
What the patent actually claims is a nozzle whose segmented extensions force adjacent exhaust streams to mix, cutting the noise they radiate. What the record doesn’t show is whether any rival ever licensed the design or deliberately engineered around it — and the retrieved official material offers no explanation either way.
Why the trade-off got harder to justify
Chevrons buy noise reduction. They also cost fuel. The serrated edges add drag in cruise, and that drag shows up as higher fuel burn on every flight — the phase where the noise benefit does nothing for anyone.
For years, that was a trade worth making. Noise rules were tightening, and a quieter nacelle helped an aircraft clear them.
But the calculus has shifted. Airlines are under intense pressure to cut emissions and operating costs, and a permanent fuel penalty is a hard sell against a noise benefit that only matters near the ground.
On the 777X, Boeing appears to have gone with a larger engine instead of external serrations — a shift that trades the serrated edge for internal acoustic work. The GE9X has an approximate 10:1 bypass ratio and a 134-inch fan diameter, about 11 feet across. Against Stage 5 limits, Boeing quotes the 777X a margin of 8 dB — with no chevrons on the nacelle.
The difference is stark: a larger, higher-bypass engine clearing a tighter noise standard with a smooth nacelle. What the public record can’t tell you is whether it’s actually quieter than a chevron-equipped GEnx or Trent 1000 under controlled conditions. No like-for-like comparison exists in the available data.
What this means for your next Asia-Pacific flight
If you fly Asia-Pacific routes, you’re already boarding the aircraft at the center of this. The 787 and 737 MAX are workhorses on long-haul and regional networks across the region — the planes that still carry chevrons.
Practically, that means the design question touches the cabin noise and comfort of aircraft you actually fly. It also feeds into route economics: if chevrons carry a fuel penalty, that cost sits inside the operating math of the routes you book, and inside how airlines weigh future fleet choices between chevron-equipped and smooth-nacelle aircraft.
The honest takeaway is narrower than the headline. No manufacturer has said chevrons are being retired. What the production record shows is that Boeing’s newest widebody doesn’t have them, and no rival ever adopted them. Watch the next Boeing or rival nacelle announcement — that’s where the answer will show up, if it shows up at all.
Reporting by
Key terms
- Nacelle
- The nacelle is the aerodynamic housing around an aircraft engine, shaping the air that enters the fan and the exhaust that leaves it. On modern high-bypass turbofans it also carries much of the acoustic treatment, from internal liners to the serrated trailing edges known as chevrons. The 777X’s nacelle is where Boeing’s change is most visible, though the retrieved official pages don’t detail the internal liner or nozzle design enough to call it a complete substitute for chevrons.
- Bypass ratio
- Bypass ratio is the proportion of air that flows around an engine’s core compared with the air that passes through it. Higher ratios generally mean a larger fan moving more air at lower speed, which tends to be quieter and more fuel-efficient. The GE9X pairs a high bypass ratio with a 60:1 overall pressure ratio, part of the same push toward doing acoustic and efficiency work inside the engine rather than on the nacelle edge.
- Stage 5 noise limits
- Stage 5 is the current round of aircraft noise limits, the standard that new aircraft types are measured against. It caps how much sound an aircraft may radiate, and compliance is expressed as a margin in EPNdB. GE Aerospace describes the GE9X as built for current and expected noise rules, which is the regulatory backdrop to the 777X’s chevron-free design.
- EPNdB
- EPNdB, or effective perceived noise in decibels, is the unit used to express aircraft noise-certification levels, weighting sound for how the human ear perceives it. Certification margins are quoted in EPNdB, which is why a noise figure is a certification number rather than a cabin-noise measurement. That’s the unit a like-for-like comparison would need to use, and no such comparison between the chevron-free GE9X and a chevron-equipped engine has been published.
Questions? Answers.
What patent number covers Boeing’s chevron noise-reduction design?
It’s U.S. Patent 6,612,106 B2, held by The Boeing Company. The filing covers a segmented mixing device that uses chevrons to cut jet-engine exhaust noise, and its priority date is May 5, 2000. The patent has since expired.
What is the GE9X’s bypass ratio and fan diameter?
The GE9X runs an approximate 10:1 bypass ratio with a 134-inch fan diameter, per GE Aerospace. It powers the 777X, which Boeing credits with an 8 dB margin to Stage 5 limits.
Has Boeing publicly stated that it is phasing out chevrons?
No. Neither Boeing nor GE Aerospace has publicly tied the 777X’s lack of chevrons to a phase-out decision. The pattern is an inference from the production record, not a confirmed corporate strategy.
