Explaining the 9/11 Murray St Engine from Flight 175 (N612UA) that hit WTC2

Mick West

Administrator
Staff member
Murray St Flight 175 Engine.jpg

When United Flight 175 hit World Trade Center Tower 2 on 9/11 some large parts of it passed through the building and landed in the streets to the north. One of these was a badly damaged core part of an engine. This landed at the intersection of Murray st and Church St.

This engine has long been part of 9/11 "Truther" mythology, with claims that it was impossible that it was used in the 767 (registration N612UA) that took off as Flight 175. This led to claims that the plane that hit the building was a modified drone, or even that there was no plane at all, and the engine was planted there, or in more extreme variants shot out of a cannon from inside the building.

Since it has been so long I presumed this has been already addressed numerous times. But when I went to look it up I found a lot of dead links, broken images, and very long threads.

I think it would be useful to gather together a concise summary of the facts behind this supposed "smoking gun". First because it's going to keep coming up, but secondly it's such a long accepted part of the mythology. Hence clearly demonstrating that it is in fact the correct engine might give the more open-minded Truther some pause for thought.

The Truther objection seem to hinge around the ring of rounded 90° tubes on a ring shaped cooling duct assembly visible at the top of the engine as it sits on Murray St.
engine1-watermarked-truther-claim.jpg

So there's this, which is claimed to be what should have been on the engine:


And this, which looks like what we actually see.



So the claim is that the 767 engine was a JT9D-7R4D, but the part was for a JT9D-7A.

Despite some digging, I'm unable to find simple answers to the following two questions:

1) How do we know what engine was in N612UA?
2) Is there a bent-tube part like that in the engine that was in N612UA?

The type of engine question seems to end up with a broken unarchived link on an IP address that no-longer hosts anything. But the info must exist somewhere.

There's a thread on ISF, much discussion, many broken links:
http://www.internationalskeptics.com/forums/showthread.php?t=208381

The sense I got from that thread was that many people thought that the two parts were not interchangeable - one was a duct, the other was a duct assembly, so perhaps one was attached to the other. But I did not get a clear answer. It is however hard to see how they could be functionally interchangeable. The point of the cooling duct is to blow cooler air on the turbine blades, the part without the tubes looks like something to transport the air around the outside - i.e. a part that would come before the bent tube part.

So basically I'd like to gather the actual facts here, and edit this post into a useful explanation of those facts. I realize this is old stuff, but it keeps coming up, and if I have a hard time finding the info, then most people will. So I invite more seasoned 9/11 investigators and people familiar with aircraft engines (@Oystein, @Keith Beachy, @benthamitemetric, @Cube Radio, @Jeffrey Orling, @jaydeehess, @Redwood, @MikeC, etc, ) to help out in creating this concise explanation. Hopefully it's already been done somewhere - but if not then I think it would be very useful to gather it here for future generations of 9/11 investigators.
 

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Mick West

Administrator
Staff member
So the claim is that the 767 engine was a JT9D-7R4D, but the part was for a JT9D-7A.

Here's a JT9D-7RD4 with what looks like the same duct:
Source: https://plus.google.com/+FredRobel/posts/HmQ8WfDkQVj


Fred Robel
Aircraft & Aviation Maintenance
Apr 29, 2017

The TOBI duct, which provides cooling air to the High Pressure Turbine disk, pokes out amidst a sea of clear plastic wrap, as it encircles the engine center shaft area.

We keep the plastic wrap over the outer part of the engine, to keep from dropping things down into the combustion can, through the NGV assemblies, which ring the outside of the area.

Pratt JT9D-7R4D aircraft engine buildup.
Content from External Source

20170829-114909-bii9a.jpg
 

Mick West

Administrator
Staff member
Well that was quick :) I think the above image pretty much proves that even if the 767 had a JT9D-7R4D then the TOBI duct looks like this . I await objections.
 

Mick West

Administrator
Staff member
More from Fred Robles. This one is great for showing the relative size of the engine part to the whole engine.
20170829-123218-pjqy0.jpg
Doing a final area inspection of the aft end of the Diffuser case/Combustion module, before installing the HPT over top of it.

Can't have any foreign crap floating around in there.

Pratt JT9D-7R4D assembly
Content from External Source
And a close up from here.
20170829-123515-ld05h.jpg
 

Mick West

Administrator
Staff member
Possible complication:
https://aviation-safety.net/database/record.php?id=20010911-1

Registration: N612UA
Engines: 2 Pratt & Whitney JT9D-7R4D
Content from External Source
Linked NTSB Report
https://reports.aviation-safety.net/2001/20010911-1_B762_N612UA.pdf
Engine Manufacturer: Pratt & Whitney
Engine Model/Series: PW4062
Content from External Source
The PW4062 is a newer version of the same type of engine. Might just have been an assumption in this initial report. Not a huge complication, as the original claim is debunked. But it might be useful to get a definitive answer as to what type of engine was used.

The FAA lists it as "P & W 52054"
http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=N612UA

Which says "JT9D Series".
http://registry.faa.gov/aircraftinq...etxt=P+&+W+++++&Modeltxt=JT9D+SERIES&PageNo=1
 
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Mick West

Administrator
Staff member
Engine part scale comparison. You can see it's a relatively small part of a larger engine. Drag the slider.

[compare]
engine overlay B.jpg engine overlay A.jpg
[/compare]

Just some more JTRD-7RD4 Images for perspective. Whenever you look at images of engines you have to consider which layers are in place (or in this case, cut away)
20170829-143241-xkgbd.jpg
Source: http://www.jetmidwestgroup.com/engines
 

Redwood

Active Member
I can't be of any help here. I have no practical knowledge of jet engines, and I try to keep from commenting on issues beyond my competence.
 

Mick West

Administrator
Staff member
The Boeing 757/767 Flight Crew Training Manual lists one engine type in the landing angle diagrams for the 767-200, the JT9D-7RD4. The 767-300 has this listed plus the RB211-524, PW4000 and CF6-80C2. The 767-400 only lists the CF6-80C2. This initially seems strong evidence that the 767-200 only used JT9D-7RD4. If other engines were possible then they would need an entry on the 767-200 chart, like they do on the 767-200 chart.
20170830-081235-zlmta.jpg
20170830-081551-j39b7.jpg

However this is contradicted somewhat by the Aviation Safety Networks report, which says flight AA11 (WCT1/North Tower/First Impact) had GE CF6-80A2 engines. AA11 was a 767-223ER (Extended Range), whereas UA175 was a 767-222
 
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WayPastVNE

New Member
I have these screen shots from Service Bulletin SB 72-512 that describe how to modify PN 769316 on the JT9D-7R4D engine.

In short the engine was exceeding temp limit, so they drilled four !/4" holes in the face of PN 76316 and then it become PN 815392.






Unfortunately the link I had to this service bulletin is now dead and the pdf I downloaded died with my last computer.
 

Gaffer_INC

New Member
I have these screen shots from Service Bulletin SB 72-512 that describe how to modify PN 769316 on the JT9D-7R4D engine.

In short the engine was exceeding temp limit, so they drilled four !/4" holes in the face of PN 76316 and then it become PN 815392.






Unfortunately the link I had to this service bulletin is now dead and the pdf I downloaded died with my last computer.
any possibility that the desired data was archived on the "wayback" https://archive.org/web/
or?
 
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WeedWhacker

Senior Member
The Boeing 757/767 Flight Crew Training Manual lists one engine type in the landing angle diagrams for the 767-200, the JT9D-7RD4. The 767-300 has this listed plus the RB211-524, PW4000 and CF6-80C2. The 767-400 only lists the CF6-80C2. This initially seems strong evidence that the 767-200 only used JT9D-7RD4. If other engines were possible then they would need an entry on the 767-200 chart, like they do on the 767-200 chart.
20170830-081235-zlmta.jpg
20170830-081551-j39b7.jpg

However this is contradicted somewhat by the Aviation Safety Networks report, which says flight AA11 (WCT1/North Tower/First Impact) had GE CF6-80A2 engines. AA11 was a 767-223ER (Extended Range), whereas UA175 was a 767-222


Mick. since I actually flew a B-757 AND B-767? OUR B-757 had the Rolls Royce engines....Our B-767 had the GE engine.

We trained for both.....
 

benthamitemetric

Senior Member
I just received in the mail a copy of Above Hallowed Ground: A Photographic Record of September 11, 2001, which was published by the Photographers of the New York City Police Department in 2002.

Though perhaps not quite so composed as Joel Meyerowitz's indispensable tome Aftermath, the collection of photos in this book is incredible and this should be a ready reference for anyone with a deep interest in understanding the events of September 11 and the recovery at Ground Zero.

Of interest to this thread--the book contains a section dedicated to documenting some of the aircraft pieces identified by the NYPD on scene, including the Murray Street engine:

IMG_4906.jpg
 
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