DC-10 Documentary

[jezza5]

I'm researching on a documentary for National Geographic Channel about the crash of flight 191 (a DC-10-10) in 1979 just outside Chicago airport. I was hoping there might be a DC-10 pilot/ex-pilot or someone who has worked with these planes who might be able to help us with a few questions. Primarily we are trying to locate a hydraulics diagram of a DC-10, even just a basic outline if possible. There is also a few other small details we would really like to hear direct from someone who has worked with these aircraft. Is there anyone who might be able to help, perhaps even speak briefly on the phone? Any help would be hugely appreciated...

Jez Bradshaw

[Rollingthunder]

Have you tried Googling for the info?

http://faalessons.workforceconnect.org/l2/UAL232/fig13

I'm sure there is more available.

[jezza5]

Yeah, have got hold of all the images on the net but what we're after in particular is the basic hydraulic layout along the main fuesalage and the wings so we can produce a basic CGI skeleton of the plane ande have the hydraulic lines running down the fuesalage and into the wing. Can't seem to find this sort of diagram sadly..

[Fly380]

There was a very detailed documentary on this crash which was aired on either The Discovery or History Channel. They still keep repeating it.

[Tarq57]

http://aviation-safety.net/database/record.php?id=19790525-2&lang=en
Might be of some use. At the bottom of the accident brief, is a link to download the full NTSB report (PDF file, 5.5megs)
Haven't read it all, or recently, but you might possibly find a hydraulic diagram in an appendix.
Other idea, contact "flight International" (the magazine). They might well have a detailed diagram of the aircraft in their files.
Just out of interest, why the curiosity about the hydraulics?

[vs69]

From what i've read about the accident the hydraulic system was considered to be a factor in the aircraft crashing as the aircraft should have (in theory at least) been able to continue flying (though im not sure if this theory applied for losing an engine on rotation) but due to the hydraulic pipes being ruptured and no hydraulic fuses being in place meant there was no pressure in the lines so the leading edge devices began to retract causing the wing to drop and giving a major uncommanded roll which is visible from photos of the accident. I am only going on what I have read about this so am ready and willing to be corrected on the matter!
Incidentally check out Air disaster 2 by Macarthur Job, well worth reading and gives a very detailed report on AA191

[jezza5]

That is exactly it, we've got a copy of tyhe report but sadly it doesn't contain a diagram of the overall hydraulic system. Technically the plane should have been able to fly without the engine had they not reduced speed to V2; the official procedure for engine out but this caused the left wing to stall the fatal roll caused the crash. One of the other things we were hoping to find out was if they had regained control, would it have been normal procedure to turn around and land again at the same airport or would this not have been possible, we do know that the ATC'er offered them the chance to land at any runway they requested but it was laready too late. Would the retration of the slats have made a normal landing difficult?

[Captb747]

Jezza5.................Check your PM,s

[Frangible]

Boeing might get you such a diagram. Might be easier to get hold of an old flight crew manual, which will have a hydraulics diagram.
The hydraulics interest is because the detaching engine ripped out a hydraulic circuit which cause the slats to retract and also an electrical (or was it hydraulic) circuit that prevented the stick-shaker from working.

What channel/series is this for?

[Brian Abraham]

Commercial purveyors have quite cheap technical manuals available. Do a Google for flight manuals.

[GlueBall]

jezza5"...we do know that the ATC'er offered them the chance to land at any runway they requested but it was already too late.

This statement obviously suggests that you have insufficient elementary aviation background. You would be well to do to consult with an aviation journo who holds at least a private pilot's license :ouch:

[Captb747]

Glueball.....................er thats probably why he is on this site? To get help ? :p

[Engineer]

Taken from the AMM
Number 1 System
http://i72.imagethrust.com/t/284972/hydraulicsystem1.jpg (http://i72.imagethrust.com/images/1c8k/view-image/hydraulic-system-1.html)
Number 3 System
http://i72.imagethrust.com/t/284973/hydraulicsystem3.jpg (http://i72.imagethrust.com/images/1c8m/view-image/hydraulic-system-3.html)

From the two diagrams it can be appreciated that the outboard slat control valve is situated in the part of the leading edge section that detached when the engine and pylon fell away. This resulted in the loss of 1 and 3 hydraulic power removing the hydraulic lock which normally holds the outboard slats in position against airloads. Without this hydraulic lock the outboard slats retracted causing an assymetric condition.

The controversial part might be why did the aircraft stall and roll left to an unrecoverable situation? The aircraft emergency procedures cover lost of hydraulics, engine failure, assymetric slats and lost of No1 generator. Maybe on the flight deck the multiple failures simply overwhelmed the crew.

[Biggles' Apprentice]

Engineer

Wasn't it something to do with AA's (or McDD's) SOP on engine loss at T/O?

[Captb747]

I believe the engine was changed using a fork lift truck which I also believe was an approved SOP for engine changes at the time (sure I will be corrected if this is not the case) In doing this the pins bent and ultimatelty sheared.

I could be wrong := but it does go something like that.:ok:

[Biggles' Apprentice]

I believe the engine was changed using a fork lift truck which I also believe was an approved SOP for engine changes at the time (sure I will be corrected if this is not the case) In doing this the pins bent and ultimatelty sheared.

I could be wrong := but it does go something like that.:ok:


Skipper, sort of right. I believe that is was an AA modified SOP which was non McDD approved, but they 'knew about it'. At the same time Delta (or someone) had a similar proceedure, but also secured the engine via overhead crane as they removed it. Neither methodology was strictly in-line with the McDD SOP, and indeed a similar bulkhead deformation was found on another Delta (or whichever the other airline was) which employed the chain secured method.

I also recall the whole incident process was clouded by some gung-ho muppet from NTSB finding a sheared bolt and initially claiming that fatigue was the cause, thus diverting the focus from the real issue. McDD did some checking of the bolts on various 10's and discovered damaged pylons/bulkheads on a couple of airplanes. NTSB subsequently found the deformed bulkhead caused by pylon impact when the engine shifted slightly on the fork lift and hey presto! the whole puzzle was solved.

I believe the left wing stall was caused by a number of conspiring factors rather than one single issue.

1) When the pylon ripped out, it damaged both the primary and backup hydrualic systems, which both ran parrallel and adjacent to the leading edge.
2) The resultant loss of hydrualics caused the slats to fail safe back into the wing as previously noted on this thread.
3) The SOP for engine lost on T/O caused for an amelioration of speed (back to v2) and altiude, which resulted in a lack of lift to the left wing and a partial stall. This was componded by localised vorticices/turbulence around the hole on the leading edge. Had they have booted it, then they might have got away with it.
4) THe pilots and FE were, according totally unaware that the engine had DETACHED and assumed it was a failure rather than a detachment, which is natural in a space of 1 minute or so.

If I am wrong about some of the above then note I'm doing this from recall!

[Biggles' Apprentice]

Skipper

As Colombo would say...there's just one more thing...

Re the pins bending, not totally true. To be pedantic, the retaining flange on the bulkhead had become deformed when the engine pranged into it, which allowed play in the pylon bolts, thus putting further strain on them and THEN they sheared, if that all makes sense.

Cheers.
Biggles.

[Biggles' Apprentice]

. One of the other things we were hoping to find out was if they had regained control, would it have been normal procedure to turn around and land again at the same airport or would this not have been possible, we do know that the ATC'er offered them the chance to land at any runway they requested but it was laready too late. Would the retration of the slats have made a normal landing difficult?

Jezza

Couple of points re above. It might (should) have been possible to regain control by gaining lift on the port wing through acceleration (not SOP) and then retracting starboard slats, trimming to overcome port wing drag. The key issue here would have been MOTW and fuel dumping prior to any emergency landing, irrespective of where, which inevitably would have been a pretty hot one. Also to consider would have been port landing gear (was it operational?) and port control surfaces (ditto)

[Engineer]

Captb747
Almost right := AA, to comply with a SB for replacement of the pylon aft bulkhead's spherical bearing, decided to remove the engine and pylon as a complete unit. thus saving manhours. This was achieved by using the forklift method which MDC did not approve, but also did not disapprove of. The method of installation caused fatigue cracks on the aft spherical bearing mount.
On AA191 the mount gave way resulting in the crash. The DC10 was grounded for a short period whilst inspections were carried out. These revealed that some AA and Continental aircraft (Contintental employed a similiar method of removing the complete unit) also had fatigue cracks :{. If you are interested the NTSB database (http://www.ntsb.gov/ntsb/brief.asp?ev_id=36919&key=0) shows the probable cause.
Biggles' Apprentice
The SOP for engine failure was modified due to an SB (22-107) which affected what speed was used after an engine failure. This would not have had an adverse effect on the way the engine failure would have been handle in my opinion

[forget]

For factual (broad) background I suggest you pick up a copy of 'Air Disasters' by Stanley Stewart. Published 1986 by Ian Allan. ISBN 1 85648 182 4.

[Captb747]

Engineer and Biggles Apprentice. Thank you for the further insight. Knew I would have left out some major factors there but thank you for putting me in the picture...:D

[Biggles' Apprentice]

Engineer

Thanks for filling the missing bits in. Yes, you're right it was CO not DL, my bad, and you are spot on re the SB.

This would not have had an adverse effect on the way the engine failure would have been handle in my opinion

Hmmm, not on FAILURE, but on detachment and loss of hydualics, I'd contest that. As I pointed out, it was the chain of events, rather than one specific event.

[Engineer]

With reference to the accident numerous tests were carried out in the simulator using different crews.
Recreating loss of the pylon and engine, which would result in a cofg change, loss of engine power and electrics. Regarding electrics, power should have been reinstated via the bus tie system. However this may not have happened so one may assume that No1 AC bus was not reinstated. Since the slat disagree warning and stall warning are powered by this bus. There would have been no indication of the slat disagreement ie slat assymetry. In theory No2 Stall system should have picked up a stall and activated the stick shaker.
If again it is assumed this did not occur the crew had no indication of impending stall.
No1 Hydraulic system would have been loss immediatley the engine/pylon seperated and with the rupture of No3 line, after a period of time, this would have been depleted. As stated in a previous post the outboard LH slats retracted.
All of these were programmed into the simulator and it was determined that the aircraft was still flyable. The saving grace here is that when you enter the sim with hindsight, as these crews did, it is not quite the same as when it happen to you for the first time :uhoh:

[Biggles' Apprentice]

The saving grace here is that when you enter the sim with hindsight, as these crews did, it is not quite the same as when it happen to you for the first time

Hear, hear. I'm never wrong in hindsight.

Wise words indeed. Thanks for the full SP on this, Engine.

[rhovsquared]

Engineer
Wasn't it something to do with AA's (or McDD's) SOP on engine loss at T/O?
Yes, they were pulling up the nose to the correct speed for flying with one engine out called V2= safety speed for takeoff with an engine loss...but until the time of this accident I think most SOP dictated that be done, yet hind sight is 20:20. probably doing such was even written/or endorsed by the manufacturer...terrible, terrible accident :(
Radio Displacement... Height...Airspeed... Incidence...Attitude...Rate of Decent... Altitude...Power Setting...Radio Displacement... Height...Airspeed... Incidence...Attitude...Rate of Decent... Altitude...Power Setting... Airspeed:}
rhov :)