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

Simple question on old 747SP incident...

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

Simple question on old 747SP incident...

Old 19th Feb 2019, 22:21
  #1 (permalink)  
Thread Starter
 
Join Date: Oct 2006
Location: USA
Posts: 282
Simple question on old 747SP incident...

If the #1 engine had been retarded to match the low thrust #4 engine, would the aircraft have remained level? Not passing judgement just curious.
https://www.thisdayinaviation.com/19-february-1985/
wrench1 is offline  
Old 19th Feb 2019, 22:30
  #2 (permalink)  
 
Join Date: Mar 2005
Location: N/A
Posts: 2,744
Would remain wings level but would descend due lack of overall thrust, forgetting about engaged autopilot modes. Depending on engaged autopilot modes it may be possible for the aircraft to maintain altitude and deaccelerate to the point of stalling..
megan is offline  
Old 19th Feb 2019, 22:43
  #3 (permalink)  
 
Join Date: Jul 2001
Location: Australia
Posts: 4,840
Originally Posted by wrench1 View Post
If the #1 engine had been retarded to match the low thrust #4 engine, would the aircraft have remained level? Not passing judgement just curious.
https://www.thisdayinaviation.com/19-february-1985/
The core issue was inattention --- nobody "flying the aeroplane".
Everybody concentrating on "the problem", at the expense of "Rule 1- Fly the Aeroplane".
The way that story is written gives a wrong impression of how the control was lost, refer to the original accident report for what really happened.
Speaking as somebody who took a great interest, as I was flying SPs at the time.
Tootle pip!!
LeadSled is offline  
Old 19th Feb 2019, 23:04
  #4 (permalink)  
 
Join Date: Mar 2012
Location: Florida USA
Age: 56
Posts: 1
Lead you were probably flying RR power a different animal to the JT9-7AH with a mind of its own if the bleeds are off or water/ice in the EVC vain control up and down and power shift all day long.

We would bring it back to part power trimmed the airplane and see how it behaved. At the same time requested decent say 360 to 320 dependent of weight and current altitude or a lower altitude off the FE chart once in the drift down. If the #1 didn't behave bring back to flight idle and leave it there. At flight idle if still mis behaving shutdown and advise ATC #1 shutdown and proceeding 3 engine normal operations and update you new weigh point times . At all stages trimming off the thrust reduction with right rudder ( ball in centre ) and bumping the remaining engines up a little on the power dependent on the weights. The SP would fly fine on 3 motors no need to panic grab another coffee and press on if you have the available gas.
4 Holer is offline  
Old 19th Feb 2019, 23:09
  #5 (permalink)  
 
Join Date: Feb 2002
Location: UK
Age: 54
Posts: 2,639
4 holer are you sure about that?
TURIN is offline  
Old 19th Feb 2019, 23:45
  #6 (permalink)  
 
Join Date: Jul 2013
Location: Everett, WA
Age: 64
Posts: 2,333
Originally Posted by wrench1 View Post
If the #1 engine had been retarded to match the low thrust #4 engine, would the aircraft have remained level? Not passing judgement just curious.
https://www.thisdayinaviation.com/19-february-1985/
Yes, but all they really needed to do was disconnect the autothrottle autopilot, and retrim the aircraft for the thrust imbalance. LeadSled is correct - nobody was flying the aircraft - they were all busy trying to start an engine while thousands of feet above the restart envelope while expecting the autopilot to do something it was never intended to do. By design, the autopilot on the the older 747s didn't have enough authority to overcome an outboard engine power loss - so that an autopilot hard over would be no worse than an engine failure (remember, we're talking 1970s vintage analog electronics).

Last edited by tdracer; 20th Feb 2019 at 02:08. Reason: My bad, wrote autothrottle, meant autopilot...
tdracer is online now  
Old 20th Feb 2019, 01:42
  #7 (permalink)  
 
Join Date: Mar 2002
Location: Florida
Posts: 5,081
does not the autopilot come into this by trying to maintain altitude and thus let the aircraft slow down and/or roll into a weak engine?
lomapaseo is offline  
Old 20th Feb 2019, 02:08
  #8 (permalink)  
 
Join Date: Jul 2013
Location: Everett, WA
Age: 64
Posts: 2,333
Yea lomapaseo - I've edited to fix - I was thinking autopilot but wrote autothrottle and didn't catch the error until I read your post and wondered why you were repeating me....
tdracer is online now  
Old 20th Feb 2019, 02:26
  #9 (permalink)  
 
Join Date: Aug 2006
Location: USA
Posts: 140
Some basic training is amiss! Using roll control to counteract to correct the situation was a mistake. The rudder should have been the primary control input to correct the situation. Even if the unresponsive engine was at idle thrust there should have been more than enough rudder to keep the aircraft flying straight at flight level (this was a Boeing not an Airbus) or maybe a slow decent to three engine flight level. One would need the charts to confirm what the allowable three engine flight level would have been. I doubt that it could have maintained FL 410, all dependent on temperature and weight. A quick think back tells me that the two engine FL would have been most likely either side of FL 210, or maybe a bit lower. Retarding the other outboard was a big mistake. With two engines producing thrust and two at idle the aircraft will have to start descending. Check the drift down chart for what the target speed would be and adjust as altitude drops and the aircraft will level off on its own when that FL has been reached.

I have not read the full report, but using the autopilot with altitude hold and lots of roll control only compounded the problem.

One of the other problems comes from all of our cultures. The senior officer (oldest) is always right. This happened a long time ago, and maybe we have all learned that each crew member has an input and all suggested should be considered.

Last edited by mustangsally; 20th Feb 2019 at 13:28.
mustangsally is offline  
Old 20th Feb 2019, 08:19
  #11 (permalink)  
 
Join Date: Jun 2001
Location: OZ
Posts: 938
The short answer to your question wrench1 is yes. But, and a big BUT, the aircraft would have stalled anyway.
I have a bit of time on B747 of all types, -100, -200, -300, -SP, -400. Now this SP was behaving exactly as advertised, Nav Mode INS, ALT Hold will always give this result with a high altitude engine failure unless crew takes action fairly quickly.
I was FEO on SP but in all my time operating jets at high altitude we always knew the 3 eng alt, always. Most of us kept it updated on our notepad and some Cpt required it on the pedestal behind the TL updated half hourly.
Eng failure triggered an automatic response from the crews in my airline that we have just a few minutes before we descend.
This incident shows the crew in a very poor light. Fatigue excuses accepted but the flight crew is responsible to be able to safely operate the aircraft, if not don't go. Yes, to answer the obvious question, I have personally pulled the pin due to fatigue.
mustafagander is offline  
Old 20th Feb 2019, 13:15
  #12 (permalink)  
 
Join Date: Jul 2001
Location: Australia
Posts: 4,840
Originally Posted by 4 Holer View Post
Lead you were probably flying RR power a different animal to the JT9-7AH with a mind of its own if the bleeds are off or water/ice in the EVC vain control up and down and power shift all day long.
.
4 Holer,
Gee, thanks for that, didn't notice that the SPs I was flying had Rollers- I will pay more attention next time.

Seriously, if you took the trouble to read the actual accident report, perhaps ( I don't know your real aviation experience, if any) you would realise that what happened --- IN LOSING CONTROL ---- had nothing to do with what engines were fitted, a 747SP with Rollers would have done the same thing.

They were all head down, frigging around with "THE PROBLEM", nobody flying the aeroplane.

And, by the way, I have plenty of time nursing various JT-9 from the -3A through various iterations of the -7, up to the JT-9D-7RE, including quite a bit of relevant hands-on "experience" of the bleed system, also the behavior of the HP fuel pumps and the results for the VIGV controllers.

As a consequence, I much preferred the CF6/80-C2 in the various thrust ratings I used it.

Tootle pip!!
LeadSled is offline  
Old 21st Feb 2019, 07:45
  #13 (permalink)  
 
Join Date: Jun 2002
Location: CYYC (Calgary)
Posts: 4,802
but neither pilot or copilot applied any rudder inpbut neither pilot or copilot applied any rudder inputs to correct the yaw. (It was later determined that they believed, incorrectly, that the autopilot controlled rudder position.
Unebelievable. An incompetent crew. Did they fly again?

a peak 5.1 Gs at 19,083 feet
Over 5 G in a commercial jet. I imagine the passengers thought they were going to die and I guess they very nearly did.

What’s the ultimate load factor for a 747 SP?
India Four Two is offline  
Old 26th Feb 2019, 01:47
  #14 (permalink)  
 
Join Date: Mar 2015
Location: CYUL
Posts: 31
Years ago I saw that same 747 SP with the shredded elevators on the ramp in SFO. It got my attention..

Much later on a 767-200 flight; my leg, level at FL410 , coming North from Barbados at night, the airspeed was slowly decreasing, and I noticed the yoke slowly rolling to the right ! I immediately remembered the China Air incident.
Checked the engine instruments, and (small EPR gauges on EFIS) left engine had rolled back to zero thrust. Generator still on line; I disconnected the autopilot, and started a drift down to engine out altitude, EO driftdown speed came up as 217 K , but no way I was going to bring speed back that far. I wanted more rudder authority. We were manoeuvring around some TCU in the descent too so I hand flew it while the Capt. did the checklist..
Engine was surging in descent, but by FL 370 or so it had recovered. Never had to shut it down, EGT didn't rise..

Last edited by Retired DC9 driver; 26th Feb 2019 at 01:57.
Retired DC9 driver is offline  
Old 26th Feb 2019, 04:55
  #15 (permalink)  
 
Join Date: May 2009
Location: sfo
Age: 66
Posts: 293
I had a view out my office window of the aircraft after it arrived in SFO and was towed off to remote parking. Taking a look from the ground, it was apparent to me that the APU mounts failed somewhere below 5.1 Gs. Never got a look at the interior, but I heard it was trashed.
sb_sfo is offline  
Old 26th Feb 2019, 07:05
  #16 (permalink)  
 
Join Date: Nov 2007
Location: Texas
Posts: 1,783
Originally Posted by India Four Two View Post

Over 5 G in a commercial jet. I imagine the passengers thought they were going to die and I guess they very nearly did.

What’s the ultimate load factor for a 747 SP?
More than 5.1. The aircraft was repaired and returned to service with a little extra wing dihedral.
MarkerInbound is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

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