Saturday, February 20, 2021

Boeing 777-222, N772UA: Incident occurred February 20, 2021 in Broomfield, Colorado

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; Denver, Colorado

Location: Broomfield, CO
Incident Number: DCA21FA085
Date & Time: February 20, 2021, 13:09 Local 
Registration: N772UA
Aircraft: Boeing 777-222 
Injuries: 239 None
Flight Conducted Under: Part 121: Air carrier - Scheduled

On February 20, 2021, about 1309 mountain standard time (MST), United Airlines flight 328, a Boeing 777-222, N772UA, experienced a failure of the right engine, a Pratt & Whitney PW4077, while climbing through an altitude of about 12,500 feet mean sea level (msl) shortly after takeoff from Denver International Airport (DEN), Denver, Colorado. There were no injuries to the 239 passengers and crew onboard, and the airplane sustained minor damage. The regularly scheduled domestic passenger flight was operating under the provisions of Title 14 Code of Federal Regulations (CFR) Part 121 from DEN to Daniel K. Inouye International Airport (HNL), Honolulu, Hawaii.

Investigative updates can be found on the NTSB website at the “United Airlines Flight 328 Boeing 777 Engine Incident” investigation page.

Aircraft and Owner/Operator Information

Aircraft Make: Boeing 
Registration: N772UA
Model/Series: 777-222
Aircraft Category: Airplane
Amateur Built: No
Operating Certificate(s) Held: Flag carrier (121)
Operator Designator Code:

Meteorological Information and Flight Plan

Conditions at Accident Site:
Condition of Light:
Observation Facility, Elevation: 
Observation Time:
Distance from Accident Site:
Temperature/Dew Point:
Lowest Cloud Condition: 
Wind Speed/Gusts, Direction: / ,
Lowest Ceiling: 
Altimeter Setting: 
Type of Flight Plan Filed:
Departure Point: Denver, CO (DEN) 
Destination: Honolulu , HI (HNL)

Wreckage and Impact Information

Crew Injuries: 10 None 
Aircraft Damage: Minor
Passenger Injuries: 229 None
Aircraft Fire: None
Ground Injuries: 
Aircraft Explosion: None
Total Injuries: 239 None
Latitude, Longitude: 39.929179,-104.96439

United’s Recent Engine Failure Spooked Denver. It’s Happened Before.

The U.S. aviation industry and FAA acted only haltingly—until last month’s emergency—to address a safety hazard: jet-turbine covers that tear away

When a Boeing 777’s engine cover broke apart and rained parts on a Denver suburb on Feb. 20, the news rang familiar to Christopher Behnam. In February 2018, the 777 he was piloting as captain suffered a similar emergency with the same engine type.

His plane, United Airlines Flight 1175 to Honolulu, was over the ocean 120 miles from the runway carrying more than 370 passengers and crew when a violent blast rocked it.

The jet shook uncontrollably, rolled sharply, and the noise was deafening, said Capt. Behnam. An engine had suffered severe damage. Years of training kicked in, the pilots regained control and shut the engine down. Even so, the plane was hard to handle. A third pilot went into the cabin and looked out the window: The engine hadn’t just failed; its cover had ripped away.

“After the explosion, it felt like she was going to fall apart,” Capt. Behnam said. “I knew I could fly the airplane. The issue was, can I fly it long enough to land it?” The pilots brought the plane to a safe landing in Hawaii.

Capt. Christopher Behnam with failed engine after landing in Honolulu, February 2018.

The National Transportation Safety Board, which investigates U.S. aviation failures, concluded that a roughly 35-pound fan blade broke in the plane’s Pratt & Whitney PW4000 engine due to fatigue, spiraling forward and causing parts of the engine cover to drop into the sea.

Until last month’s Colorado incident involving United Flight 328, the aviation industry and the Federal Aviation Administration had acted only haltingly to address such breakups. That’s despite a series of such failures starting at least five years ago.

Engine “fan blade-outs” are an old problem in aviation. But in recent cases involving Boeing airliners, fast-spinning blade fragments have shot forward into the engine’s inlet, rather than into a protective casing that acts like a bulletproof vest around the sides.

That has resulted in another problem. Engine covers sometimes aren’t surviving those blade fractures, creating bigger hazards for planes, passengers and people on the ground.

A similar engine-cover emergency had hit a Southwest Airlines Co. Boeing 737 flight in 2016. At least three more happened after Capt. Behnam’s flight. Two months after his scare, a Southwest engine cover broke and blasted out a window; a passenger was partially sucked out and died. On Dec. 4, 2020, an engine broke up on a 777 flight near Japan.

Regulators, engine makers and airlines have confronted the problem with a short-term remedy. With varying degrees of urgency in recent years, they have stepped up fan-blade inspections to find pre-fracture cracks that could lead to engine covers ripping off.

Emergency Aloft

In a string of incidents since 2016, engine fan blades have fractured and caused a problem: engine covers ripping off midair. Such a scenario played out on a Boeing 777 bound for Hawaii in 2018:

Despite working on modifications and replacements for more than two years, plane maker Boeing Co., which is responsible for engine coverings on its aircraft, and the FAA have yet to finalize plans to redesign the types of engine covers that have ripped off. “We’ve already seen extreme cases,” said NTSB Chairman Robert Sumwalt. “It is something that the industry needs to get on top of and get corrected immediately.”

Complicating the industry’s response to the safety hazard is that it requires coordination among several segments—airplane manufacturers, engine makers, airlines—and among different engineers and regulators focused on avoiding fan-blade fractures and still others focused on preventing engine covers from detaching midair.

In the U.S., that puts the FAA in the best position to tackle the hazard. Its handling of the engine breakups is the regulator’s first big test since its fumbled responses to fatal Boeing 737 MAX crashes in 2018 and 2019.

The FAA declined to make senior agency officials available for interviews. A spokesman said a priority has been reducing the risk of fan-blade failures that can lead to engine covers detaching midair. The FAA spokesman said design changes to a “critical piece of structure must be carefully evaluated and tested” to ensure they provide the same level of safety or better without introducing unintended risks.

Boeing spokesman Bradley Akubuiro said the company “has taken steps to move forward” with the FAA to improve engine covers and is giving its technical teams time they need to ensure any of the manufacturer’s design changes provide their expected performance and maintain overall safety. While designing changes is “exacting and time-consuming,” he said, “this work has been, and remains, a high priority.”

Southwest spokeswoman Brandy King said the airline’s leaders, including Chief Executive Gary Kelly, were focused on understanding and learning from the carrier’s fatal accident while working with manufacturers to prevent similar tragedies in the future. Pratt & Whitney and United Airlines Holdings Inc. declined to comment.

Planes made by Airbus SE haven’t experienced any such engine-cover breakups due to fan-blade fractures in recent years, according to the European Union Aviation Safety Agency, the primary regulator for Boeing’s rival across the Atlantic.

Over the past five years, the problem of engine covers detaching due to fan-blade failures that spew parts forward appears to have primarily surfaced on two Boeing aircraft types, the 777 and 737, which use engines made by different manufacturers, according to current and former FAA officials.

To keep fan blades from breaking in the first place, regulators have focused first on stepping up inspections. Within days of the Dec. 4 engine breakup near Japan, Tokyo’s air-safety regulators ordered new engine inspections—visual checks and ultraviolet-light tests, a Japanese aviation official said.

The FAA opted against immediate action and was still considering its next step when the United 777’s engine broke apart near Denver last month. Before that incident, Pratt & Whitney, a unit of Raytheon Technologies Corp. , was considering issuing a service bulletin telling airlines to conduct specialized inspections of certain 777 engines every 1,000 flights, said the NTSB’s Mr. Sumwalt. The FAA had required the deep inspections every 6,500 flights after the 2018 incident in Hawaii.

The FAA declined to comment about its response to the December breakup. The agency said it makes safety-oversight decisions in a rigorous, well-established analytical process aimed at quickly identifying and mitigating risk, adding: “To suggest that there is commonality among different events ignores the fact that data for different events is unique to each specific event.”

Early warning

An early warning about the risk that engine covers could crumble when broken blades fly far enough forward came in August 2016. A Southwest flight from New Orleans to Orlando made an emergency landing after an engine failed—a fan blade broke, causing significant damage and leading the cabin to depressurize. One of the engine’s 24 fan blades had broken due to fatigue, NTSB investigators found.

The spinning blade had careened into the front inlet where air flows into the engine. Most of the inlet broke off, spitting debris into the Boeing 737 jet’s fuselage, wing and horizontal stabilizer.

Regulators and industry experts, including at the NTSB, generally viewed that event as a one-off, the NTSB’s Mr. Sumwalt said.

The engine’s manufacturer, CFM International—a joint venture of General Electric Co. and France’s Safran SA —developed a new, more high-tech inspection protocol using ultrasound technology. A GE spokesman speaking on behalf of the joint venture said the engine maker worked with regulators and customers to enhance and implement inspection procedures and remained committed to working on changes stemming from the NTSB’s recommendations.

The FAA in 2017 considered mandating additional fan-blade testing, though it didn’t require additional checks until the following year when it ordered emergency inspections in the aftermath of the fatal engine-cover breakup on another Southwest flight.

“We determined early that we would require some corrective action and that it was an unsafe condition,” Christopher Spinney, an FAA engine specialist, said during an NTSB hearing in 2018. “But we also determined that we had some time.” Mr. Spinney, through an FAA spokesman, declined to comment.

On Capt. Behnam’s flight that year, after the fan blade scattered parts of the 777’s engine cover, the plane’s aerodynamics were out of whack. It felt, he said, like “having an open barn door” on the right side of the plane.

Two months later on a Southwest 737, debris from an engine covering—again loosened by a broken fan blade—smashed into the plane’s body, blasting out the window through which the passenger was partially sucked.

She was the first U.S. airline-passenger fatality in nearly a decade and Southwest’s first passenger fatality. After the death, Mr. Kelly, Southwest’s CEO, pushed Boeing for an engine-cover fix to avoid a repeat of such a tragedy, according to a person familiar with the plane maker’s work on the 737 engine cover.

After those incidents, the industry began to grapple with vulnerable engine covers. Not only were fan blades failing, they were doing damage to engine coverings that had been expected to withstand such events.

Boeing engineers were particularly concerned about a potential loss of control should engine covers break off and damage a plane’s horizontal stabilizer, said the person familiar with the plane maker’s work.

Engine makers put their engines through a battery of tests to make sure they will hold together if a fan blade breaks. They are largely focused on making sure debris doesn’t go through the side of the engine casing, where it could penetrate the body of the plane. Broken fan blades can still cause damage by flying forward.

Coverings go through their own certification process on a separate track.

While engine coverings are expected to contain broken fan blades, they aren’t designed to shield more-serious failures of hubs the blades are attached to—as happened on an Airbus A380 jet over Greenland in 2017. Parts fell off at 37,000 feet, damaging buildings but causing no injuries.

Within about two weeks of that incident, the FAA issued an emergency order requiring inspections on roughly 120 of the jets equipped with certain engines produced by Engine Alliance, a joint venture between GE and Pratt & Whitney. GE referred inquiries to Pratt & Whitney, which declined to comment on Engine Alliance’s behalf. An Airbus spokesman said the plane maker takes into account past incidents and accidents, including those on other manufacturers’ aircraft, to enhance safety.

Boeing engineers have been working on a plan to strengthen 737 engine covers, essentially to soften the shock of a fan-blade failure and keep parts attached to the plane even when the blades fly forward, people familiar with the work said.

In March 2020, FAA Administrator Steve Dickson told the NTSB the agency was working with the plane maker to strengthen the 737 engine covers, according to written responses to the NTSB’s recommendations. He said the agency would eventually mandate a new design change. The FAA declined to make Mr. Dickson available for an interview.

In August 2020, Boeing provided an update to the FAA on its work to also strengthen 777 engine covers. The manufacturer told regulators it had decided to redesign and make replacement covers with which airlines could retrofit their fleets, according to the FAA document.

Boeing’s 777 engine-cover fix didn’t come in time for the Dec. 4 incident near Japan, on a Japan Airlines Co. 777 with Pratt & Whitney PW4000 engines. Two of an engine’s fan blades broke shortly after takeoff from Okinawa, according to a preliminary report by Japanese investigators. Part of the engine’s cover detached, and the jet’s body and horizontal stabilizer sustained damage, the report said. A JAL spokesman declined to comment on the cause of the incident.

The FAA held off ordering immediate action. After the December incident, the agency said it reviewed the JAL engine’s maintenance and inspection history, conducted a metallurgical exam and was evaluating whether to adjust blade inspections.

It wasn’t immediately clear to investigators and regulators whether the fan-blade cracks at the root of both 777 engine breakups roughly two years apart shared the same underlying cause, according to a person familiar with the FAA’s response. Age, manufacturing defects or maintenance slip-ups can cause metal to crack and eventually fracture. The FAA declined to comment about its work with Boeing on 777 engine covers.

Since the Colorado 777 incident, Boeing has shared some of the changes it is considering to shore up 737 engine covers with carriers including Southwest and American Airlines Group Inc., said people briefed on the matter. It has also been in talks with United about potential changes to 777 engine covers, according to a person familiar with those discussions. Boeing and the FAA declined to comment on when 777 or 737 engine-cover fixes would be completed.

Japanese regulators grounded the aircraft the day after the Colorado incident. Soon thereafter, Mr. Dickson ordered immediate specialized inspections even while some FAA officials didn’t believe such drastic action was necessary, said people familiar with the agency’s response.

The move, which the FAA described as “decisive action,” effectively took more than 50 Boeing 777s with certain Pratt & Whitney engines—all operated by United—out of service for months, until inspections have been completed.

Tom Haueter, a former NTSB director of aviation safety who now consults on safety and accident investigations, said: “They grounded the fleet—that’s about as aggressive as you can get.”


Boeing Co. was planning to strengthen protective engine covers on its 777 jets months before a pair of recent serious failures, including one near Denver last weekend, according to an internal Federal Aviation Administration document.

The plane maker and regulator had been discussing potential fixes even longer—for about two years, according to people familiar with the matter. The talks began after two failures in 2018, one on a 777 operated by United Airlines Holdings Inc.and the other on a Southwest Airlines Co. 737.

Because potential modifications to 777 external engine covers, commonly known as cowlings, had various shortcomings, “Boeing has decided to redesign the fan cowl instead of trying to modify existing fan cowls to address both the structural strength concerns” and moisture issues, according to the internal FAA document reviewed by The Wall Street Journal.

“Boeing will be manufacturing new fan cowls and providing service instructions for operators to remove and replace the fan cowls,” according to the document, part of a routine Aug. 6, 2020, update on efforts under way at the agency’s Seattle-area offices. Boeing and the FAA declined to comment on the engine-cover plan’s status Wednesday.

Separately on Thursday, the FAA said Boeing would pay $6.6 million for failing to meet its obligations under a 2015 settlement and to resolve two enforcement cases.

Such changes to airplane parts can require years of design, testing and regulatory approvals. Some aviation-safety experts and regulators have been growing increasingly concerned about whether engine covers are robust enough to withstand the impact of a fan blade’s breaking off and shooting outward during flights.

While rare, such engine-cover damage has come up in a handful of recent engine failures. Pilots train to land a plane operating on one engine, which can be done safely, but large pieces of metal from covers can put other parts of the aircraft—and passengers—at risk. The engine-testing process hasn’t beenfully accounted for that possibility, according to some safety experts and reports by the National Transportation Safety Board.

Jim Hall, chairman of the NTSB from 1994 to 2001, said recent incidents should have prompted regulators to look “very aggressively“ at issues surrounding engine covers.

“I have yet to see indication this was done,” he said.

Boeing said it would continue to follow the FAA’s guidance on 777 engine covers, and it is “engaged in ongoing efforts to introduce safety and performance improvements across the fleet.”

An FAA spokesman said reducing the risk of engine fan-blade failure that could lead to cowling damage has been a priority—the focus of agency directives following the 777 incidents in 2018 and last week. FAA officials have said the agency was working with Boeing on a design change for a different type of engine that failed on the 2018 Southwest flight—killing a passenger—and reviewing the need for changes to other engines.

“Any proposed design change to a critical piece of structure must be carefully evaluated and tested to ensure it provides an equivalent or improved level of safety and does not introduce unintended risks,” the agency spokesman said.

The 777 engine failure last weekend came shortly after the plane—as in one of the 2018 incidents, operated by United—took off from Denver International Airport. An apparently weakened fan blade broke off and seemed to have sheared a second blade roughly in half, according to the NTSB, which is leading the investigation. The engine’s cover was ripped away, leaving a trail of debris in the town below.

It resembled two recent failures of certain Pratt & Whitney-made engines on a subset of Boeing 777 aircraft—the 2018 United flight and one in December of 2020 operated by Japan Airlines Co. Authorities in the U.S. and Japan attributed both to fan blades that snapped off and battered engine covers.

In all three cases, the planes landed safely without any injuries.

After the 2018 failure on the United 777, the FAA mandated that fan blades on the type of engine involved undergo special thermal-acoustic image inspections—using sound waves to detect signs of cracks—every 6,500 flights. The engine that failed over the weekend had made about 3,000 flights since its last inspection, according to people familiar with the matter.

The FAA on Monday ordered immediate thermal-acoustic image inspections for fan blades on certain Pratt & Whitney engines on some Boeing 777 jets. Pratt & Whitney is a unit of aerospace company Raytheon Technologies Corp.

But a design change to fortify engine covers is a longer, more involved process. The internal FAA document said Chicago-based Boeing had presented its 777 engine-cover findings to FAA specialists in the Seattle area in early August.

Aircraft engines and their protective covers are supposed to constrain broken fan blades and other metal parts, preventing them from damaging structures needed to keep the plane aloft. Detached engine covers that don’t fall to the ground could create aerodynamic drag, safety experts said. That could increase consumption of fuel if the plane is flying less efficiently, a concern for long flights over water with few options for emergency landings, one of these experts said. The FAA document cites “fuel exhaustion” as a potential safety hazard.

Engines’ certification tests have focused on making sure that broken fan blades don’t shoot out the side of an engine and puncture the plane’s fuselage. Less attention has been paid to the prospect that a blade could shoot forward and damage the front part of the engine covers. Those covers aren’t required to be attached during tests of how engines cope with broken fan blades so the blades remain visible.

“When you lose big pieces like that, that’s a hazard,” said Jeffrey Guzzetti, a former director of the FAA’s accident investigation division. “There was never a requirement to consider this before—it just never really happened that much.”

The FAA offered few details of Boeing’s alleged violations when it announced new penalties Thursday. The agency’s administrator, Steve Dickson, said he has “reiterated to Boeing’s leadership time and again that the company must prioritize safety and regulatory compliance.”

Boeing didn’t immediately respond to a request for comment. The plane maker has said it will follow FAA guidance on “all matters related to safety and compliance.”



  1. Video taken looking out the 777 window:

    1. Here is video from the ground that shows a black cloud from the sudden anomaly. Blew the cowling off, apparently.

    2. The twitter account limits access on who can view that video, so not all can see that, especially those without a twitter account.

      Here's a version on YouTube:

  2. Fairing opening for access video:

  3. CNN is funny at this point.... they are playing the mayday call and the announcer things that "United 328 heavy engine failure" is "heavy engine failure" rather than "United 328 heavy, engine failure."

  4. CNN is nothing but fake news. They don’t have a clue to what they are talking about. They are programmed to report their narrative and slant that information anyway they want to. They will probably blame climate change or President Trump this incident. MANY KUDOS TO THE FLIGHT and CABIN CREW for a suburb job in handling this situation.

    1. That's CNN for ya. Remember their "The 777 will struggle to stay in the air with no fuel" remark a few years ago.

  5. Good thing that engine didn't fail halfway over the Pacific. Don't know if it would have made it.

    1. It's certified for at least 3 hours of single engine operations, so it'd be interesting, but otherwise a non-event.

    2. The vibration from the windmilling unbalanced rotor was stress testing the pod mount in fatigue mode. Three hours of that and the galley would run out of complimentary adult beverages.

  6. This video shows missing blade view in the first 20 seconds:

  7. suggest crew was aware of the engine issue prior to the explosion ...
    "out for a walk with his family when he noticed a large commercial plane flying unusually low and took out his phone to film it.

    “While I was looking at it, I saw an explosion and then the cloud of smoke and some debris falling from it."

    1. N772UA was not any lower on the incident day than when that same aircraft and flight number passed over Broomfield on 14 February.

      Turn on speed/altitude ADS-B labeling by clicking the "K" tab in those two tracks below and compare the data points as it passed by Broomfield.

      20 Feb N772UA incident flight:

      14 Feb N772UA normal flight:

  8. Two photos below show that only the forward cowling blew off initially, then fire burned through the cowling portion behind it:

    Early photo before burn through:

    Later photo with burn through underway:

  9. NHK news is reporting that the Japanese transport ministry has issued an order to halt domestic operation of Boeing 777 aircraft following the United Airlines flight 328 engine failure.

    On December 4, 2020 Japan Airlines 777-289 JA8978 (flight JAL/JL904) suffered engine failure six minutes after takeoff. Broken fan blades similar to the 2018 N773UA failure (NTSB DCA18IA092) were noted. All Nippon Airways and Japan Airlines have fleets of 19 and 13 of the 777-200 series jets.

    Photos and text (in Japanese) of the JA8978 failure in JTSB press release:

  10. Ramp photos of hole found in unpressurized lower fuselage N772UA:

    Wide view:

    Close view:

  11. These engines are marvels of aerospace engineering that we tend to take for granted. A second marvel is that the Denver plane was able to land safely with no physical harm to passengers, crew or anyone on the ground. The disturbing part of the story was the human failure to inspect engines properly.

    1. I respectfully disagree. The most disturbing part of the story is that there is obviously a fundamental design and/or manufacturing defect in these “marvelous” engines which PW has apparently not addressed directly but just transformed it into a sloppy inspection problem.

    2. Only a person who is unaware of the 2018 N773UA failure investigation findings would claim "fundamental flaw" in 9,606 blades that have been in service since the mid 90's.

      The difficulties and shortcomings related to inspection of those blades is the story to go read about.

    3. In 2000, over 2,000 PW4000 engines had accumulated over 40 million hours of service with 75 operators. In 30 years between June 1987 and 2017, more than 2,500 engines have been delivered, logging more than 135 million flight hours.

      Now about your car- no problems driving the same model for 30 years and running it every day at the local 1/4 mile drag strip before driving to work ?

      And simply checking it every 5 years or so ?

  12. NTSB Report from the 2018 N773UA failure (NTSB DCA18IA092):

    Powerplants Group Chairman's factual report:

  13. In pictures you can see one of the fan blades missing. This is a 112" diameter fan meaning each fan blade is ~50" long. I believe this fan spins at ~4000 RPM at maximum power output so when one of them 'comes undone' at speed, the 'check underpants' light starts flashing pretty quick. It will be interesting to see the forensic metallurgy results on the blade components. Most likely a fatigue failure. So very thankful the fugitive blade went a different direction than the passenger compartment.

  14. My house and neighborhood are directly over one of the departure climb out waypoint paths of Atlanta's Hartsfield-Jackson. This has always been my nightmare scenario as they are accelerating and climbing some 7-10,000' overhead. I can hear freight dogs like Kalitta Air 744s and international flight 777s on climb power in the late night/early morning if I'm still awake (and check the Flightaware app to see what it is). This area is very fortunate - and United specifically - there were no ground injuries or deaths. Yikes.

  15. No panic necessary. This is what FAA does. This is why there are two engines on these aircraft. And over time any design weakness will reveal itself. The mfg, Boeing and FAA will slice and dice this thing down to the serial number, date and location and who was on the clock during final assembly and the last inspection cycle. Yes, those kinds of records are kept. The last time it was a metallurgical issue with fan blades on the Rolls Royce engine. Determined it to be part of a batch run, date specific, and with each blade having a serial number, all were replaced. There was microscopic contamination causing the vibration which, at those rpm’s, led to failure. Not noticeable by visual inspection, which when an engine is in service is usually how they are inspected in each maintenance cycle [to the best of my knowledge, I only talk to these mechanics, I’m not one of them]. This is what the industry designs for and the detail of tracking will result in a fix, or we wouldn't pilot them.

    1. The PW4000 and its contemporaries at GE and RR were the first engines to really heavily utilize composites and advanced alloys, as well as innovative machining techniques producing hollow and curved fan blades. These engines are now getting on 20-25 years. We really don't have a lot of data on reliability and failure frequency of these first -generation advanced components. But three uncontained failures on PW4000s in as many years is a red flag.

  16. What are the chances that the blade debris will be found? I'm surprised they haven't offered a serious reward for it.

    1. They don't need the portions that departed because the base remnant of the missing blade and the lower portion of the second blade are still in their running position and the fracture faces can be seen.

      The NTSB reporting of the 2018 N773UA blade failure linked a few comments above provides all the details from that investigation. Changes were made after N773UA to improve blade inspection. The Denver blade failure investigation is likely to focus mostly on blade inspection history and process after the basic fracture failure is compared to the N773UA incident.

  17. Glad all parties are safe, WoW.. What a Failure that was. Guess their going to need more than a Broom in Broomfield, Sorry i couldn't resist...

  18. Boeing has had its problems but this isn't really one of them. Boeing doesn't build or maintain engines and the customers tell Boeing what engines to install. Of course, Boeing is the integrator and has bottom line responsibility. Unfortunately, most people don't know that. Most engines are made by GE or Rolls Royce or Pratt and Whitney.

  19. A question for the aviation experts (or armchair pseudo-experts): Does Airbus have these blade and cowling problems? The last Airbus crash I can remember was the Air France Rio-Paris disaster and that proved to be pitot tubes and pilot error.

    My concern with Boeing is that they are looking like the less safe of the two manufacturers. And yes, I realize that's probably unfair, but that seems to be the image that is developing.

    1. Ask instead: Should there be an expectation that Airbus cowlings would withstand the identical blade fragment impact events?

      Answer: No

      Reasoning: No aircraft manufacturer's cowlings had a design requirement to withstand impact from blade fragments that travel forward of engine fan casing containment.

    2. Not quite. The airframe mfg is required to design the cowl to withstand forward moving blades according to the mfg specs. But the common assumption is that the forward helix angle would be <15 deg. Recent experience shows this is overoptimistic.

    3. Airbus was also designing to that common assumption of <15 deg for their cowlings.

      The answer regarding withstand expectation is still: No

    4. I'm tellin' ya'... if that 12-foot diameter ring of cowl ended up in MY backyard, I would now have the world's coolest kiddie pool!

    5. My thoughts exactly. I would have definitely at least asked if I could keep it.

  20. 777 safety record: one accident per eighteen-million hours of flying.

    Designed in the early 90's by veteran Boeing engineers in the era where we knew how to check our hand calculations with FEA, not relying on FEA as a crutch.

    Give me a 777 flown by a USAF or USN veteran and I will sleep soundly on any flight. (sorry for the snoring).

    Put/keep the engineers and pilots in charge and Boeing will continue to build great aircraft.

  21. Might it help if the FAA was no longer a subsidiary of Boeing and instead it were to be an independent agency?