Pratt & Whitney и все вокруг

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- удивительно, но ветку про P&W искал\не нашел:
Redesign to cure acoustic engine phenomenon linked to A220 failures
Redesign to cure acoustic engine phenomenon linked to A220 failures
By David Kaminski-Morrow5 March 2021

Pratt & Whitney is aiming to introduce redesigned bleed-valve ducts for Airbus A220 engines by the fourth quarter of this year, to eliminate a resonance phenomenon linked to a series of powerplant failures.
Four instances of PW1500G low-pressure compressor stage-one rotor separation, affecting A220-300s operated by Swiss and Air Baltic, occurred in the seven months between July 2019 and February 2020.
Engine parameters at the time of each failure, and the resulting damage, was “consistent” for all the events, says the US National Transportation Safety Board, which has completed an investigation into the first incident, involving a Swiss A220 (HB-JCM).
The aircraft’s left-hand engine failed as it climbed through 32,000ft over Perrigny-sur-Armancon in France while en route to London Heathrow. Examination of the twinjet after it diverted to Paris Charles de Gaulle revealed a hole in the low-pressure compressor casing and the stage-one rotor was missing.
A220 failed engine-c-NTSB

Source: NTSB
Analysis of the failed engine from HB-JCM traced the rotor fracture to resonance
Investigators conducted multiple tests including computational fluid dynamic and acoustics analysis to identify the cause of the failure.
These tests identified a mechanically-coupled mode excitation between the stage-one and stage-three rotors of the low-pressure compressor, driven by an “acoustic coincidence” with the 2.5 bleed-valve duct cavity.
At high engine speeds in specific operating conditions, says the inquiry, the low-pressure compressor rotor blade tips could cause turbulent airflow that generated an acoustic tone as it passed over this cavity, which is situated immediately behind the compressor.
This tone excited a stage-three rotor blade bending mode which was then mechanically transferred, through the low-pressure compressor module, to the stage-one rotor – generating a bending mode in that rotor which exceeded the stress limits on its blades.
The stresses created cracks in the blade root and rotor which worsened until the rotor failed from overload.
A220 failed engine LPC case-c-NTSB

Source: NTSB
Damage to the low-pressure compressor case resulting from the rotor failure
Three of the A220 engine failures involved the PW1524 variant of the powerplant while the other occurred to a PW1521.
Investigators determined that a software revision to the electronic engine control, which altered the compressor’s variable inlet guide vane schedule, increased the likelihood of blade-flutter onset.
Operating restrictions – including a thrust limitation at high altitude – were imposed on A220s in the aftermath of the engine failures to reduce the chances of the phenomenon being initiated, and amended engine-control software was also introduced to restore the original vane schedule.
But Pratt & Whitney is also modifying the geometry of the 2.5 bleed-valve duct, says the inquiry, in order to increase frequency margins and eradicate the problematic resonant response. It adds that the redesigned hardware is scheduled to be available by the fourth quarter.
 
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Fuel did not feed PW4000 engine fire following engine failure: NTSB
By Jon Hemmerdinger6 March 2021

A Boeing 777-200 engine fire following an engine failure last month was not fed by fuel and burned outside the core of the Pratt & Whitney PW4077 turbofan.
That is according to the National Transportation Safety Board (NTSB), which on 5 March says the pilots were successful in shutting off fuel to the badly damaged engine.
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Source: National Transportation Safety Board
Fire damage to the inboard side of the 777-200 PW4077 engine that failed on 20 February 2021
In an investigation update, the NTSB also reveals more details about the incident and says investigators found evidence of metal fatigue on the engine’s failed fan blade.
The 20 February incident involved a United Airlines 777 (registration N772UA) operating flight 328 from Denver to Honolulu.
“Initial examination of the right engine fire damage… found it was primarily contained to the engine’s accessory components, thrust reverser skin and composite honeycomb structure of the inboard and outboard thrust reversers,” the NTSB says.
Early after the accident, the agency said it was seeking both to understand why the engine failed and why it remained on fire following the failure.
Twitter Marc Sallinger

Source: Screenshot of Twitter post by Marc Sallinger, @marcsallinger
Video of a PW4077 engine failure on 20 February 2021. The engine was powering a United Airlines 777-200.
“The spar valve, which stops fuel flow to the engine when the fire switch is pulled in the cockpit, was found closed. There was no evidence of a fuel-fed fire,” the NTSB says. “Examination of the engine accessories showed multiple broken fuel, oil and hydraulic lines, and the gearbox was fractured.”
The engine’s aft cowling “appeared to be intact and undamaged, and all four pressure relief doors were found in the open position”.
Shortly after taking off from Denver, at about 12,500ft altitude and travelling at about 280kt (519km/h), the pilots of United flight 328 “advanced power” to limit the amount of time the aircraft would be flying through turbulence.
“Immediately after the throttles were advanced a loud bang was recorded on the [cockpit voice recorder],” the NTSB says. Information from the flight data recorder indicates “the engine made an uncommanded shutdown”.
The pilots declared an emergency and “discharged both fire bottles into the engine”. Needing to get on the ground quick, they did not dump fuel, the NTSB says.
On the power of a single engine, the captain piloted the aircraft back to Denver, landing without injuries to any passengers or crew.
Examining the engine, investigators found one blade “was fractured transversely across the airfoil about 5in above the base of the blade at the leading edge and about 7.5in above the base of the blade at the trailing edge”.
PW4077 777 United 328 failure

Source: National Transportation Safety Board
Damage to fan blades of a United Airlines Boeing 777-200’s PW4077 engine, which failed in flight on 20 February 2021
“Preliminary findings from the scanning electron microscope examination have identified multiple fatigue fracture origins on the interior surface of a cavity within the blade,” the NTSB says. “The blade’s fracture surface was consistent with fatigue.”
When the blade failed, the engine had been in service for 2,979 flight cycles since its previous inspection. It had undergone thermal acoustic image (TAI) inspections in 2014 and 2016, and the 2016 data had been re-examined in 2018 following a similar inflight failure that year of a 777’s PW4000, the NTSB notes.
On 22 February, P&W issued a “special instruction” that calls for affected engines’ fan blades to undergo TAI inspections at 1,000-cycle intervals. The following day, the US Federal Aviation Administration issued an emergency order requiring airliners to complete the inspections before further flight.
Boeing 777-200 PW4077 failure. United Airlines

Source: National Transportation Safety Board
This PW4077 turbofan, powering a United Airlines 777-200, failed in flight on 20 February 2021
 

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Pratt & Whitney Makes Hypersonic Revival As Pentagon Pushes Reuse
Guy Norris Steve Trimble March 05, 2021
Lockheed Martin SR-71
The turbo-ramjet configuration of the J58 engine inspires the reusable, high-speed propulsion technology for Pratt & Whitney’s Metacomet program.
Credit: U.S. Air Force

As reusable hypersonic propulsion rises up the list of U.S. Defense Department priorities, Pratt & Whitney now confirms it is working on a secretive development program called Metacomet aimed at solving the problem of fielding high-speed, reusable propulsion systems at low cost.
Already at least two years old, Metacomet—a name linked to a 17th century Wampanoag chief, the namesake of a ridge overlooking a Pratt & Whitney research facility in Connecticut—marks the company’s return to Mach 3-plus propulsion nearly a decade after selling its scramjet pioneer Rocketdyne arm to the parent company of Aerojet in 2012.
  • Metacomet leverages SR-71 engine architecture
  • Pentagon strategizes for reusable hypersonic push
  • NASA, commercial sectors offer new options
With the intellectual property of the former Rocketdyne off limits, Pratt & Whitney’s GatorWorks division—a prototyping unit formed in 2018—launched Metacomet to focus on low-cost alternatives to ramjet and scramjet propulsion for high-speed flight.
The effort draws on the company’s expertise with gas turbine combat engines, and in particular reaches back to decades-old experience with the unique J58 engine developed for the Mach 3-plus Lockheed SR-71. That aircraft achieved sustained flight above the Mach cutoff point of a normal turbojet by diverting inlet air from the compressor directly into the afterburner.
“The faster you go, the larger the propulsion system is relative to the vehicle and how much payload and fuel you can actually fit in,” says David Stagney, senior director of GatorWorks. “So, we have spent a lot of time going back to the fundamentals and thinking about how to solve that problem differently. We know the Air Force wants to go really fast. They also want to have some very low-cost solutions, and to be able to have a large quantity of vehicles.”
As a result, Stagney says Pratt & Whitney is tackling the problem from a new perspective. “We think that we can provide unique capabilities building on the legacy we have from the Mach 3 engine that we built [several] decades ago,” he says. “Those core skills are still there, and our goal in GatorWorks is to come up with a whole portfolio of different solutions for a range of high-Mach solutions.”
The engine-maker believes its design approach, which is thought to be tailored to higher speeds above Mach 3 but below Mach 5, is simpler and more affordable because it avoids the need for pure ramjet/scramjet cycles or the complexities of mode transition to and from turbine power.
“Obviously, there are trade-offs between speed, range, cost and the amount of payload that you can take and fit onto a vehicle that makes sense economically,” Stagney says.
Metacomet appears to blur the normal distinction between “high-supersonic” and “hypersonic” regimes. Describing hypersonic as anything that travels faster than Mach 5 is a widely accepted definition—albeit arbitrary. To air vehicle designers, a hypersonic condition refers to a range of aerodynamic and thermal effects that arise at different speeds above Mach 5. They vary depending on the vehicle design and flight profile of the vehicle. These effects strongly influence the materials and shaping of the airframe, as well as the type of propulsion that is possible.
Stagney’s remarks about Metacomet suggest the program is pursuing engine configurations that can approach or exceed the arbitrary speed definition of the hypersonic term, but fall short of encountering the special aerodynamic and thermal effects at a system level.
“We’ve come up with some really unique different solutions to that problem across the whole spectrum of speeds,” he adds. “We want to offer different solutions that aren’t being thought about right now and that are much lower cost per effect.”
The work is particularly focused on reusability and a scalable architecture that can be applied to suit varying mission priorities across a combination of different sizes, payloads, ranges and speeds.
Although the company declines to provide specifics of the Metacomet solution set, test plans or potential applications, Stagney says the Air Force Research Laboratory’s (AFRL) proposed Mayhem demonstrator vehicle for a hypersonic, air-breathing propulsion system “is definitely one of the programs that we’re looking at, for sure.”
The AFRL revealed plans for the Mayhem System Demonstrator on Aug. 13 as a “larger-scale, expendable, air-breathing, hypersonic, multimission” platform that can carry “larger payloads over distances further than current hypersonic capabilities allow,” according to a formal request for information that was released to industry.
Despite its vintage, the J58, which was developed in the 1960s and retired when NASA ended test flights of the SR-71 in 1997, remains one of the most successful and ingeniously designed high-speed air-breathing engines.
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While the engine’s close integration with the SR-71 airframe played a key role, the bulk of its success can be attributed to the aero-mechanical features of the J58 turbojet itself. These included axisymmetric mixed compression inlets and airframe-mounted, convergent-divergent blow-in door ejector nozzles—all aspects that could potentially be further developed for 21st-century applications.
The J58’s inlet spike, which translated longitudinally depending on Mach number, controlled the throat area and provided a stable shock structure across the speed range close to Mach 3.3. Above Mach 2.2 some airflow was bled from the compressor and fed through bypass ducts into the augmenter, transitioning the engine from a pure turbojet into a turbo-ramjet. At design cruise speed around 70-80% of the net propulsive force is derived from flow compression pressure on the spike.
However, as the turbine section was still partially interacting with the flow path, the maximum speed was governed by aerodynamic heating of the flow and the 800F temperature limit reached shortly after Mach 3.2. Aerodynamic analysis has indicated that the inlet design has the potential for operating at speeds up to and beyond Mach 5. Moreover, a configuration based on the J58 could go significantly faster than Mach 3.3 if modern materials and advanced cooling systems were incorporated to expand the temperature limits in the compressor.
Another potential area of improvement would be the modulation of the inlet flow and boundary layer. Other inlet controls in the J58 included the forward and aft bypass doors and the cowl and spike bleeds—which controlled boundary layer growth.
Later in service, including the final operational phase with NASA, the introduction of a digital automatic flight and inlet control system to orchestrate the position of the engine spikes and forward bypass doors had virtually eliminated the problem of inlet unstarts that hampered the aircraft in its early operation. Further improvement in control, and therefore performance, could be possible through the introduction of modern processors and faster actuators.
For additional performance growth, an updated J58 cycle could also conceivably provide a step toward higher Mach numbers. Options would include changes to the compressor design, materials improvements and adding supersonic combustion capability in the afterburner section. This radical redesign would also likely include fully closing off the turbine section for the maximum cruise condition.
Pratt & Whitney may also be dusting off J58 upgrade concepts studied in the late 1990s, when NASA evaluated boosting performance of the SR-71 to support its potential use in launching high-speed research vehicles and carrying captive experimental packages to higher speeds and altitudes. Some of these additional concepts involved increasing turbine exhaust temperature, raising compressor rotor speed, augmenting afterburner flow, and modifying compressor bleed and inlet guide vane schedules.
Lockheed Martin SR-72

Lockheed Martin’s 2013 concept for the SR-72 could leverage a high-speed, reusable propulsion system for surveillance and strike missions. Credit: Lockheed Martin
Pratt & Whitney’s pursuit of a reusable, high-speed propulsion system comes as the Defense Department’s Research and Engineering (R&E) branch starts to look beyond the initial rush to field multiple prototypes of offensive and defensive hypersonic weapon systems within this decade. If the push materializes into a new development program, the Defense Department could support the first reusable, operational system since the cancellation of the Lockheed Martin X-33 suborbital technology demonstrator in 2001.
The R&E branch is now developing a strategy to field reusable hypersonic systems to serve the strike and intelligence, surveillance and reconnaissance missions, as well as the first stage of a two-stage system for rapid access to orbital space, a Pentagon spokesman says.
The strategy document introduces the third element of the Pentagon’s wider plans for hypersonic technology.
Expendable missiles expected to be fielded within the next 2-5 years—such as the Lockheed Martin AGM-183 Air-Launched Rapid Response Weapon, the Army’s Long-Range Hypersonic Weapon, the Navy’s Intermediate-Range Conventional Prompt Strike and the Air Force’s Hypersonic Attack Cruise Missile-—comprise the first element. The Missile Defense Agency’s plans to deliver a terminal interceptor against hypersonic missiles in the mid-2020s, followed by a Glide Phase Interceptor in the late 2020s, represent the second element.
In addition to Mayhem and Pratt & Whitney’s offerings, the Defense Department also continues to develop a turbine-based combined-cycle engine. The Advanced Full-Range Engine, a project sponsored by DARPA and the Air Force, combines an off-the-shelf turbine engine—for flight up to Mach 2.5—with a dual-mode ramjet engine capable of supersonic combustion to reach speeds greater than Mach 5.
The path to reusable hypersonic propulsion also includes civil and commercial programs. NASA’s aeronautics research arm, for example, has launched the Hypersonic Technology project, which includes a special focus on reusable vehicle technologies for the airframe and propulsion system. The Air Force’s AFWerx innovation unit also is conducting market research on a proposal to provide financial and engineering support to commercial companies developing hypersonic passenger jets under the Vector Prime program.
The AFWerx effort could give a boost to several companies, including Reaction Engines and startup Hermeus.
“We are glad to see that initiative gaining momentum,” says Hermeus CEO AJ Piplica in an interview. “In our past lives, we’ve certainly been able to benefit from that kind of situation where the government opens up test facilities—whether it’s ground test or flight test—and then partners with commercial industry to generate data in new parts of the flight regime that we’ve never been in before.
“Being able to do that for supersonic and hypersonic flight could really provide some acceleration to both the industry and an Air Force road map for reusable hypersonic flight that is currently 15-20 years out,” Piplica adds. “So, if by partnering together with industry we’re able to shave 5-10 years off that road map, that would be a major win for the country.”
norrisguysized.jpg

Guy Norris
Guy is a Senior Editor for Aviation Week, based in Los Angeles. Before joining Aviation Week in 2007, Guy was with Flight International, first as technical editor based in the U.K. and most recently as U.S. West Coast editor. Before joining Flight, he was London correspondent for Interavia, part of Jane's Information Group.
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Steve Trimble
Steve covers military aviation, missiles and space for the Aviation Week Network, based in Washington DC.
 

Александр Артюков

Новичок
За последние месяцы было два инцидента с двигателями PW на B777

Как результат, японцы ускорили вывод этих 777 из эксплуатации

 

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Japan Airlines Permanently Grounds PW4000-powered 777s
by Gregory Polek
- April 6, 2021, 1:16 PM
Japan Airlines has decided not to return its 13 Pratt & Whitney PW4000-112-powered Boeing 777s to service following their suspension of operations due to recent in-flight engine failures, including a December 4 incident involving a JAL 777-200. The airline had planned to retire its Pratt-powered 777s by March of next year but has accelerated their removal in favor of service with Airbus A350-900s on domestic routes out of Osaka and shift other aircraft flying international service to maintain frequencies on flights within the country.
Japan grounded a total of 31 PW4000-112-powered 777s flown by JAL and All Nippon Airways on February 21, a day after a United Airlines 777-200's PW4000-112 failed soon after taking off from Denver on a flight to Honolulu. U.S. investigators found evidence of fan blade metal fatigue in the PW4000-112 engine that failed, raining nacelle debris over a mile-long area of a Denver suburb.
National Transportation Safety Board examinations found one blade fractured at the root, an adjacent blade fractured at about mid-span, and a portion of one embedded in the containment ring. The remainder of the blades showed damage to the tips and leading edges.
The NTSB continues to investigate the relationship between the latest PW4000 failure and previous events, such as a 2018 incident in which another of the engines in a United Airlines 777-200 suffered a fan blade failure on approach to Honolulu.
In the 2018 incident, investigators determined that a fractured fan blade caused the failure. Last year the NTSB determined that insufficient training for a thermal acoustic imaging (TAI) inspection process developed by Pratt & Whitney led to technicians misdiagnosing a problem with the fan blade that ultimately failed in the 2018 incident. Since then Pratt & Whitney developed a formal training curriculum for the inspections. The FAA issued an airworthiness directive in March 2019 requiring repetitive inspections of all PW4000s in service.
Meanwhile, Japanese investigators continue their probe into the case of a PW4000 failure that involved a Japan Airlines 777-200 flying from Naha Airport in Okinawa to Tokyo Narita Airport. That airplane also landed safely after returning to Naha Airport.
“We will continue to fully cooperate and respond to the investigation by the Japan Transport Safety Board to determine the cause of the incident,” said JAL in a statement.