Go Back  PPRuNe Forums > Flight Deck Forums > Rumours & News
Reload this Page >

Another 777 uncommanded engine rollback

Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

Another 777 uncommanded engine rollback

Old 18th Dec 2008, 16:01
  #1 (permalink)  
Thread Starter
 
Join Date: Jan 2005
Location: France
Posts: 2,316
Another 777 uncommanded engine rollback

NTSB e-mail, December 18, 2008
NTSB INVESTIGATING LOSS OF ENGINE POWER ON DELTA AIR LINES BOEING 777

The National Transportation Safety Board is investigating an
incident in which a Delta Air Lines Boeing 777 experienced
an uncommanded engine rollback in the cruise phase of an
intercontinental flight.

On November 26, 2008, at about 12:30 pm MST, in the vicinity
of Great Falls, Montana, a 777-200ER (N862DA), operated by
Delta Air Lines as Flight 18, en route from Shanghai to
Atlanta, experienced an uncommanded rollback of the right
(number 2) Rolls-Royce Trent 895 engine while at 39,000 feet
in the cruise phase of flight. The crew executed applicable
flight manual procedures and descended to 31,000 feet. The
engine recovered and responded normally thereafter. The
flight continued to Atlanta where it landed without further
incident. None of the crew of 15 or 232 passengers was
injured.

Flight data recorders and other applicable data and
components were retrieved from the airplane for testing and
evaluation. Both of the pilots have been interviewed.

This event is preceded by another airline's 777 equipped
with Rolls-Royce Trent 895 engines, which experienced an
uncommanded dual engine rollback while on final approach to
London's Heathrow International Airport on January 17, 2008,
crashing short of the runway on airport property. The
United Kingdom's Air Accidents Investigation Branch (AAIB)
is investigating that accident.

NTSB Senior Air Safety Investigator Bill English, who is
serving as the U.S. Accredited Representative in the
Heathrow accident investigation, is the Investigator in
Charge of the Delta incident.

The AAIB, which has assigned an Accredited Representative to
the Delta incident, is working closely with the NTSB to
determine if there are issues common to both events.
ChristiaanJ is offline  
Old 18th Dec 2008, 16:18
  #2 (permalink)  
Thread Starter
 
Join Date: Jan 2005
Location: France
Posts: 2,316
Tah, GobonaStick.
I only got the NTSB e-mail minutes ago.

CJ
ChristiaanJ is offline  
Old 18th Dec 2008, 16:22
  #3 (permalink)  
 
Join Date: Mar 2006
Location: Choroni, sometimes
Posts: 1,975
Investigator Bill English, who is
serving as the U.S. Accredited Representative in the
Heathrow accident investigation,
Well, it seems the right person in the right place.
hetfield is offline  
Old 18th Dec 2008, 17:00
  #4 (permalink)  
 
Join Date: Aug 2000
Location: EGGW
Posts: 2,040
Boeing sent out an e-mail on this days ago.
Mr @ Spotty M is offline  
Old 18th Dec 2008, 18:04
  #5 (permalink)  
Thread Starter
 
Join Date: Jan 2005
Location: France
Posts: 2,316
Originally Posted by Mr @ Spotty M
Boeing sent out an e-mail on this days ago.
Any link to the contents?
ChristiaanJ is offline  
Old 18th Dec 2008, 18:37
  #6 (permalink)  
 
Join Date: Aug 2005
Location: Nice, FR
Posts: 130
This was on the original thread for the LHR incident a few days ago, I was amazed there was no response from Ppruners.
paull is offline  
Old 18th Dec 2008, 18:47
  #7 (permalink)  
 
Join Date: Apr 2002
Location: FUBAR
Posts: 3,351
Indeed, a slightly disturbing incident for sure. I wonder if a common cause or just some random electrical spike. Perhaps all the research into ice etc will prove to have been for nought and the cause for both found (or not ) to have been some transitory electrical woopsie that nobody forecast and the BITE stuff doesn't recognise.
Damned funny stuff electricity, black magic.
captplaystation is offline  
Old 18th Dec 2008, 19:09
  #8 (permalink)  
 
Join Date: Mar 2002
Location: Florida
Posts: 5,329
I was amazed there was no response from Ppruners.
Not much to be said until they look at the data and decide if the fuel control was commanding it or following it.

There are more common reasons for rollback not related to ice in the fuel.

The BA038 thread evidenced unique response of the fuel control not associated with more common causes of rollback.

I'm not saying that the fuel control is causal, only that's a indicator of where to look.
lomapaseo is offline  
Old 18th Dec 2008, 19:55
  #9 (permalink)  
 
Join Date: Apr 2004
Location: wales
Posts: 455
Similar issue a year ago with ER and GE engine resulting in a long period of non derated take offs until software modified , although this problem was only on T/O .
bvcu is offline  
Old 19th Dec 2008, 22:21
  #10 (permalink)  
 
Join Date: Apr 2004
Location: Planet Earth
Posts: 1,861
If i'm not mistaken Delta have Rolls on their -ER'S, same as the BA in LHR
stilton is offline  
Old 19th Dec 2008, 22:42
  #11 (permalink)  
 
Join Date: Sep 2005
Location: uk
Posts: 267
sems to dispell the ice in fuel explanation of the beijing incident.becoming a bit concerning if software and electrical systems are less than 100% reliable.considering the number of triples in service,i suppose no need to cause too much concern.
bermudatriangle is offline  
Old 19th Dec 2008, 22:50
  #12 (permalink)  
Psychophysiological entity
 
Join Date: Jun 2001
Location: Tweet Rob_Benham Famous author. Well, slightly famous.
Age: 80
Posts: 4,868
So how long was the remaining section of the flight?
Loose rivets is offline  
Old 19th Dec 2008, 23:13
  #13 (permalink)  
 
Join Date: Dec 2002
Location: UK
Posts: 2,018
Donít discount the weather as a cause:- The Ice Crystal Weather Threat to Engines.
safetypee is offline  
Old 20th Dec 2008, 13:21
  #14 (permalink)  
 
Join Date: Mar 2002
Location: Seat 0A
Posts: 8,012
becoming a bit concerning if software and electrical systems are less than 100% reliable.
Like QF 72: One component of one ADIRU (of three identical on board) goes haywire and the aircraft goes bananas.
Capn Bloggs is offline  
Old 20th Dec 2008, 14:07
  #15 (permalink)  
 
Join Date: Nov 2004
Location: Nowhere
Posts: 60
"becoming a bit concerning if software and electrical systems are less than 100% reliable."

I doubt any are, but they can still be more reliable then a large number of mechanical moving rods.
banana9999 is offline  
Old 20th Dec 2008, 15:30
  #16 (permalink)  
 
Join Date: Jan 2008
Location: On the lake
Age: 78
Posts: 664
a bit concerning if software and electrical systems are less than 100% reliable
Which planet are you living on?? Anything made or touched by poor, humble man (or woman) is subject to screw up and/or failure. If anybody in aviation believes anything different, they're in the wrong field of endeavour.
twochai is offline  
Old 20th Dec 2008, 17:01
  #17 (permalink)  
 
Join Date: Sep 2007
Location: Paris, France
Posts: 351
The problem is that software isn't verified as thoroughly as hardware.

Verification and certification processes were designed for mechanical systems, not ones and zeroes. Digital systems, including anything controlled by software, have failure modes that are dramatically different from those of mechanical systems, and catastrophic failures for unforeseen circumstances are the rule rather than the exception. Systems that mix software and hardware are still tested and verified as if everything were hardware, and that lets lots of potential bugs slip through the cracks.

Combine this with the extremely poor record of reliability for software engineering as a whole, and software becomes a considerable cause of concern.

I know that aviation tries harder to verify software than most other industries do, but manifestly it isn't trying hard enough, if events like this are happening. Which type of mechanical failure would roll an engine back in cruise? Weird, random, off-the-wall incidents like that have all the hallmarks of software bugs.

My specialty is information technology; aviation is my hobby. Decades of experience with IT have taught me that the more software there is in a safety-of-life system, the less it should be trusted. In an ideal world, software would be completely safe, but we are still in the Dark Ages when it comes to designing reliable software. To paraphrase a famous saying, whenever I hear "computer," I arm the pyrotechnics on my ejection seat.
AnthonyGA is offline  
Old 20th Dec 2008, 17:24
  #18 (permalink)  
Thread Starter
 
Join Date: Jan 2005
Location: France
Posts: 2,316
AnthonyGA,
Yes, no and maybe.

In the analog days, we had TWO physically separate and distinct channels, one monitoring the other. If they disagreed, they disconnected. The probability of the same op-amp or same resistor failing identically at the same time was infinitesimal.

When 'digital' came along, I had qualms as well, but dissimilar processors and dissimilar software between 'command' and 'monitor' mostly were supposed to have solved their 'identical failure' problems.

Some of those concepts now seem to have gone out of the window, judging from some recent posts elsewhere.

So far, we have no idea whether this incident is again ice or something similarly mechanical, or indeed "IT" related, so let's give it a break until we have more data?

Cabin crew spilled some Coke on the pedestal during the last flight and it now soaked through? Weirder things have happened.

I sincerely hope the QAR/FDR data will tell a useful story.

CJ
ChristiaanJ is offline  
Old 20th Dec 2008, 17:39
  #19 (permalink)  
 
Join Date: Jun 2005
Location: Cheshire, UK
Posts: 160
Cabin crew spilled some Coke on the pedestal during the last flight and it now soaked through? Weirder things have happened.
..........such as pilots spilling coke and blaming the cabin staff in the ASR...
jetsetjobbie is offline  
Old 20th Dec 2008, 18:00
  #20 (permalink)  
 
Join Date: Oct 2001
Location: UK
Age: 79
Posts: 3,693
Everywhere I have ever been in aviation, everyone who was allowed on the flight deck was taught to pass drinks to pilots around the outside and never, ever on the inside over the central pedestal.

Fluids and automatics do not mix and exciting and expensve things happen when they come together.
JW411 is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.