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c933103
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Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Sat Jul 04, 2020 9:10 am

https://www.aerotime.aero/rytis.beresne ... s-two-days
In all three incidents, the 787 was only transporting cargo so there were only crew but no passengers on-board.

How did they allow the aircraft to take off for the second and third time when the problem still persists?
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ikolkyo
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Sat Jul 04, 2020 9:56 am

Happens from time to time where the same issue just keeps persisting. I’ve seen it plenty of times on avherald reports on many different aircraft types.
 
889091
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Sat Jul 04, 2020 11:11 am

From the link provided:
"The Dreamliner (registered N27958) landed in Narita (NRT) on July 2, 2020, at 7:45 AM local time (UTC +9) from Chicago O’Hare International Airport (ORD) on flight UA2821. The B787 was supposed to continue on to Beijing Capital International Airport (PEK) on flight UA2822, but after 50 minutes of flight time, the aircraft returned to NRT after declaring an emergency at 10:46 AM local time (UTC +9).
....
The cause of all three u-turns was a malfunctioning slat of the left wing, local media reports indicate. In total, the runway was closed for 13 minutes, according to Narita officials, as the airport’s authorities inspected for any damage to the runway following the emergency landings."

Presumably they had issues retracting the LE slats? Would that warrant an emergency declaration?
 
Cointrin330
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Sat Jul 04, 2020 12:20 pm

Flew this particular bird from LAX to MEL and from SYD to LAX in 2016 and seem to recall it has had other issues with diversions in the past.
 
jayunited
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Sat Jul 04, 2020 1:15 pm

Here is some information the original flight 2822 July 2nd NRT-PEK the crew received a EICAS about 20 minutes into the flight executed the diversion and returned safely to NRT. UA maintenance at NRT spent around 3-4 hours working on the aircraft. UA also swapped the PEK and SFO aircraft to get PEK going, as that flight is a roundtrip (UA does not allow crew members to overnight in China and we had to consider NRT's curfew). After maintenance cleared the message N27958 took off heading towards SFO as UA 2770-02, the aircraft reached FL290 according to internal documentation when the EICAS message appeared again. This crew is the crew that declared the emergency, I'm not a pilot but I can imagine it is a good feeling to have an alert that a slat has deployed at FL290. Aircraft lands safely crews inspect the runway for damage. The aircraft is then taken out of service for 23 hours 37 minutes maintenance fixes the issue again. Then on July 3rd UA2770 takes off again for SFO, and again the aircraft made it up to FL290 before the EICAS message show up again this crew (which wasn't the same crew from the day before) returned to NRT but did not declare an emergency.

Aircraft is still on the ground at NRT from internal documentation this seems to be an electrical problem or fault but at no time did the actual slat deploy. UA will try to get the aircraft to SFO on July 5th assuming they have figured out what is triggering this electrical fault.
 
as739x
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Sat Jul 04, 2020 2:29 pm

c933103 wrote:
https://www.aerotime.aero/rytis.beresnevicius/25340-united-airlines-b787-uturn-three-times-two-days
In all three incidents, the 787 was only transporting cargo so there were only crew but no passengers on-board.

How did they allow the aircraft to take off for the second and third time when the problem still persists?


Not sure what you mean by how did they allow this to happen? They didn't know. Its very frequent with airplanes to fix and issue on the ground, mechanics ops check ok, then the problem pops up again. So in their mind the problem no longer persisted. Once in the AIR, systems may act different. For example a slat! You can't replicate 150mph winds pushing against the slat on the ground.

If you read Avherald enough you'll will see repeat issues of the same problem happen occasionally and probably more then the general public thinks. Repeat write-ups is one of the worst terms you can hear cause you know its going to be an extensive delay.

An example was when I was waiting at the gate for mechanics to tow an aircraft to the gate that I was taking out. The crew towed the plane in, then proceed to turn around and tow it out and return it to the hangar. After a short call with operations, turned out the plane had made and emergency landing that morning with a gear indicator issue. On the tow over, the issue popped up again, so they turned around and took her back. Hello 6 hour delay waiting for a new plane
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CriticalPoint
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Sat Jul 04, 2020 3:07 pm

c933103 wrote:
https://www.aerotime.aero/rytis.beresnevicius/25340-united-airlines-b787-uturn-three-times-two-days
In all three incidents, the 787 was only transporting cargo so there were only crew but no passengers on-board.

How did they allow the aircraft to take off for the second and third time when the problem still persists?


They didn’t “allow” the aircraft to take off with a problem. The fixed something and the message cleared. They fixed something else and the message cleared. Now they are fixing something else and hopefully it works.

Unfortunately cannot duplicate on ground is a common problem.
 
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CALTECH
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Sat Jul 04, 2020 3:12 pm

c933103 wrote:
How did they allow the aircraft to take off for the second and third time when the problem still persists?


They didn't.
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mmo
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Sat Jul 04, 2020 3:55 pm

c933103 wrote:
https://www.aerotime.aero/rytis.beresnevicius/25340-united-airlines-b787-uturn-three-times-two-days
In all three incidents, the 787 was only transporting cargo so there were only crew but no passengers on-board.

How did they allow the aircraft to take off for the second and third time when the problem still persists?



To be honest, there are certain malfunctions that can't be duplicated on the ground. This just happens to be one of them. When I worked for a US carrier with a red tail, I addition to being a line trainer, I also worked in Test and Ferry. We had a 747-200 that had a flap problem only on extension. Maintenance struggled to get it right and couldn't find anything wrong and it only happened on extension. The general feeling was the crew was extending the flaps at or slightly above the limit speed.

We got involved when Boeing AOG arrived as this was an R powered 2B it was a valuable aircraft and not having it in the schedule caused all sorts of problems. Anyhow, we flew it several days in a row and always ended up having the same problem. On the next to the last flight, the repair seemed to work until we tried alternate flaps and the same malfunction occurred.

The only thing which wasn't changed was the transmission and jackscrew. Not a cheap assembly to replace. However, Boeing was on the hook for the repair and new transmission and jackscrew were installed. We flew the aircraft a few days after the transmission and jackscrew arrived and that took care of the problem. After several months, we received a report on the problem and it turned out to be a burr on the thread of the jackscrew which when subject to air loads flexed just enough to hang up on extension in flight. Maintenance and the AOG team were all over the jackscrew trying to find something but never did as the burr was so small.

My point is maintenance did all they could to troubleshoot the problem and fix it but they could never get the right conditions to cause the burr to be a problem on flap extension.
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redrooster3
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Tue Jul 07, 2020 7:38 pm

Looks like 958 is acting up again with the same indications.

"Multiple mechanical issues due to slat and flap indications. Flight is air returning to FCO. Gonna dump fuel."
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m66
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Tue Jul 07, 2020 8:21 pm

jayunited wrote:
Here is some information the original flight 2822 July 2nd NRT-PEK the crew received a EICAS about 20 minutes into the flight executed the diversion and returned safely to NRT. UA maintenance at NRT spent around 3-4 hours working on the aircraft. UA also swapped the PEK and SFO aircraft to get PEK going, as that flight is a roundtrip (UA does not allow crew members to overnight in China and we had to consider NRT's curfew). After maintenance cleared the message N27958 took off heading towards SFO as UA 2770-02, the aircraft reached FL290 according to internal documentation when the EICAS message appeared again. This crew is the crew that declared the emergency, I'm not a pilot but I can imagine it is a good feeling to have an alert that a slat has deployed at FL290. Aircraft lands safely crews inspect the runway for damage. The aircraft is then taken out of service for 23 hours 37 minutes maintenance fixes the issue again. Then on July 3rd UA2770 takes off again for SFO, and again the aircraft made it up to FL290 before the EICAS message show up again this crew (which wasn't the same crew from the day before) returned to NRT but did not declare an emergency.


I get the feeling that plane doesn't like flying higher than FL290 :-)
 
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lightsaber
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Tue Jul 07, 2020 11:09 pm

m66 wrote:
jayunited wrote:
Here is some information the original flight 2822 July 2nd NRT-PEK the crew received a EICAS about 20 minutes into the flight executed the diversion and returned safely to NRT. UA maintenance at NRT spent around 3-4 hours working on the aircraft. UA also swapped the PEK and SFO aircraft to get PEK going, as that flight is a roundtrip (UA does not allow crew members to overnight in China and we had to consider NRT's curfew). After maintenance cleared the message N27958 took off heading towards SFO as UA 2770-02, the aircraft reached FL290 according to internal documentation when the EICAS message appeared again. This crew is the crew that declared the emergency, I'm not a pilot but I can imagine it is a good feeling to have an alert that a slat has deployed at FL290. Aircraft lands safely crews inspect the runway for damage. The aircraft is then taken out of service for 23 hours 37 minutes maintenance fixes the issue again. Then on July 3rd UA2770 takes off again for SFO, and again the aircraft made it up to FL290 before the EICAS message show up again this crew (which wasn't the same crew from the day before) returned to NRT but did not declare an emergency.


I get the feeling that plane doesn't like flying higher than FL290 :-)

I think it wants to be locked down. ;)

Perhaps with that CR9 it was eyeing.

Time to call Boeing.

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Nomadd
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Tue Jul 07, 2020 11:38 pm

I'm not familiar with the slat sensor, but I'd think a circuit fault would be identified as such and about the only way to get a false reading would be the sensor itself. Is it a simple on off?
 
FlyHossD
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Wed Jul 08, 2020 12:03 am

CALTECH wrote:
c933103 wrote:
How did they allow the aircraft to take off for the second and third time when the problem still persists?


They didn't.


Correct - NO crew with take off that way (see below).

Quoting JayUnited, "Aircraft is still on the ground at NRT from internal documentation this seems to be an electrical problem or fault but at no time did the actual slat deploy. UA will try to get the aircraft to SFO on July 5th assuming they have figured out what is triggering this electrical fault."

I saw the three issues on AvHerald a couple of days ago and from experience, I can say that NO crew would climb to FL290 knowing that a flap or slat was extended. So, it had to be an intermittent indication problem. And believe me, those intermittent problems are often just a bee-0tch to correct. In the meantime, Maintenance will be working hard to rectify the issue and will believe that they've done so before releasing the plane. And then when it happens again - ARGH! Sometimes, the problem has to get worse before the cause is finally - once and for all - found and corrected.
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FCOTSTW
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Fourth Occurrence for the Same Aircraft in Two Weeks

Wed Jul 08, 2020 4:41 pm

The United Airlines 787-9 that suffered three leading edge flap occurrrences last week in Tokyo, today stopped its climb out of FCO to return to the airpoirt. This is pretty unique and it is not certainly good publicity for United.

http://www.avherald.com/h?article=4d9aa79c&opt=0
 
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par13del
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Wed Jul 08, 2020 5:36 pm

Well I guess the mechanics wanted confirmation that they corrected all the problems with the a/c by returning it to flight sooner rather than later after more extensive checks on return to the USA.
Bummer......
 
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CALTECH
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Re: Slat problem on a UA 787 caused the same aircraft to conduct three emergency landing in two days.

Fri Jul 24, 2020 5:00 pm

FlyHossD wrote:
CALTECH wrote:
c933103 wrote:
How did they allow the aircraft to take off for the second and third time when the problem still persists?


They didn't.


Correct - NO crew with take off that way (see below).

Quoting JayUnited, "Aircraft is still on the ground at NRT from internal documentation this seems to be an electrical problem or fault but at no time did the actual slat deploy. UA will try to get the aircraft to SFO on July 5th assuming they have figured out what is triggering this electrical fault."

I saw the three issues on AvHerald a couple of days ago and from experience, I can say that NO crew would climb to FL290 knowing that a flap or slat was extended. So, it had to be an intermittent indication problem. And believe me, those intermittent problems are often just a bee-0tch to correct. In the meantime, Maintenance will be working hard to rectify the issue and will believe that they've done so before releasing the plane. And then when it happens again - ARGH! Sometimes, the problem has to get worse before the cause is finally - once and for all - found and corrected.


Spot on FlyHoss. For those who would like to know, intermittent problems are the worst to solve. Can't fix or figure out something that is working correctly . After some history with the same problem, then it will be looked into much more extensively. Happens a lot, parts replaced, think it's fixed and it faults again.
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