pilotntrng
Posts: 679
Joined: Tue Dec 16, 2003 8:13 pm

Converting Aircraft

Tue Jan 15, 2008 7:46 am

Obviously airlines that are buying used aircraft would like them to be similiar to the aircraft that they own.Sch as Delta buying AA's old TWA 757s, because of the type of engines they use. My example and question is, how hard would it be to replace a 757 with a GE engine with a RR and get them compatible with the rest of the fleet?
Booooo Lois, Yaaaa Beer!!!
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Converting Aircraft

Tue Jan 15, 2008 5:58 pm



Quoting PilotNTrng (Thread starter):
My example and question is, how hard would it be to replace a 757 with a GE engine with a RR and get them compatible with the rest of the fleet?

It's technically possible but difficult and expensive. New strut, new aisle stand, some new overhead panels, new wiring from the engine to the aircraft, new reversers. The difficulty of doing the conversion is exactly why the 787 was designed for engine changes from the beginning.

Tom.
 
2H4
Posts: 7960
Joined: Tue Oct 19, 2004 11:11 pm

RE: Converting Aircraft

Tue Jan 15, 2008 6:41 pm



Quoting Tdscanuck (Reply 1):
The difficulty of doing the conversion is exactly why the 787 was designed for engine changes from the beginning.

Interesting that other models (eg: 757/767) weren't designed similarly. It seems obvious that such interchangeability would add value to an aircraft with multiple engine options.

2H4
Intentionally Left Blank
 
futurecaptain
Posts: 1918
Joined: Sat Sep 09, 2006 1:54 am

RE: Converting Aircraft

Tue Jan 15, 2008 6:50 pm

It has been said that all things considered it is cheaper to buy a new aircraft from the manufactuer then it is to do this kind of conversion and get the plane recertified for normal pax operations.

But, if you don't want to use the plane in passenger service again...slap a GE-115 on a 747.

View Large View Medium
Click here for bigger photo!

Photo © Jet City Aviation Photography

AirSO. ASpaceO. ASOnline. ASO.com ASO. ASO. ASO. ASO. ASO.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Converting Aircraft

Tue Jan 15, 2008 7:15 pm



Quoting 2H4 (Reply 2):
Quoting Tdscanuck (Reply 1):
The difficulty of doing the conversion is exactly why the 787 was designed for engine changes from the beginning.

Interesting that other models (eg: 757/767) weren't designed similarly. It seems obvious that such interchangeability would add value to an aircraft with multiple engine options.

It was mostly driven by the shift from purchase to leasing. When the 757/767 were being designed, legacy carriers owned most of their fleets. Leasing was viewed as something for lower tier airlines. This meant that airplanes were bought straight from the manufacturer to their operator and stayed there for decades...no real demand for the ability to swap engines so little perceived value.

Fast forward 20 years and leasing companies are the biggest fleet owners out there and aircraft can go through 5+ owners in their lifetime. What the buyer (the leasing company) is looking at now is total return on their asset, not just efficiency within a particular fleet/route structure like an airline would look at. The ability to swap engines is of major value to the leasing company (although still of relatively low value to any particular airline) so, like any good supplier, the OEM's are adapting to what their new customers want.

Tom.
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: Converting Aircraft

Tue Jan 15, 2008 7:21 pm



Quoting Futurecaptain (Reply 3):
But, if you don't want to use the plane in passenger service again...slap a GE-115 on a 747.

I always found it hillarious that GE chose a Pratt-powered bird as their engine test bed  laughing 
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Converting Aircraft

Tue Jan 15, 2008 9:39 pm



Quoting KELPkid (Reply 5):
I always found it hillarious that GE chose a Pratt-powered bird as their engine test bed

Makes sense to me...get your test bird and do a little competitive "research" at the same time. Thanks to the way the FAR's work for maintenance documentation, Pratt would have to turn over all of their maintenance material to GE if GE was flying Pratt engines.

Tom.
 
Viscount724
Posts: 19287
Joined: Thu Oct 12, 2006 7:32 pm

RE: Converting Aircraft

Tue Jan 15, 2008 10:49 pm

A small number of 747s were converted from P&W to GE engines. This is one of them:

P&W:


View Large View Medium
Click here for bigger photo!

Photo © Ed Groenendijk
View Large View Medium
Click here for bigger photo!

Photo © Marc Lehmann



GE:


View Large View Medium
Click here for bigger photo!

Photo © Jordi Steeno
View Large View Medium
Click here for bigger photo!

Photo © Tim Perkins



That aircraft was written off after a landing overrun incident at DUS in 2005.
 
metroliner
Posts: 847
Joined: Sat Jan 20, 2007 4:35 am

RE: Converting Aircraft

Tue Jan 15, 2008 11:16 pm

Here's a dumb question - did any aircraft ever use more than one engine type?

Tridents excepted  Wink I know about those!

Toni

P.S. Any jokes about BAe146s having five hairdryers are anticipated forthwith...
Set the controls for the heart of the Sun
 
Viscount724
Posts: 19287
Joined: Thu Oct 12, 2006 7:32 pm

RE: Converting Aircraft

Tue Jan 15, 2008 11:54 pm



Quoting Metroliner (Reply 8):
Here's a dumb question - did any aircraft ever use more than one engine type?

Yes, a few aircraft that used a mix of piston and "helper" jet engines to provide additional power during takeoff at at heavy weights. The Boeing B-36 was probably the most notable with 6 piston engines and 4 jet engines.


View Large View Medium
Click here for bigger photo!

Photo © Ted Quackenbush
View Large View Medium
Click here for bigger photo!

Photo © Matt Bearup



Fairchild C-123 Provider military transport.


View Large View Medium
Click here for bigger photo!

Photo © Ralph M. Pettersen
View Large View Medium
Click here for bigger photo!

Photo © Gerard Helmer



Lockheed P2V Neptune maritime patrol aircraft.



Fairchild C-82 Packet (the one in the photo was used by TWA to ferry replacement Constellation engines around Europe). Note the single small jet engine on top of the fuselage.


View Large View Medium
Click here for bigger photo!

Photo © Robert Roggeman

 
User avatar
Starlionblue
Posts: 17208
Joined: Fri Feb 27, 2004 9:54 pm

RE: Converting Aircraft

Tue Jan 15, 2008 11:58 pm



Quoting Metroliner (Reply 8):
P.S. Any jokes about BAe146s having five hairdryers are anticipated forthwith...

Actually they're 5 APUs. Big grin
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: Converting Aircraft

Wed Jan 16, 2008 12:52 am



Quoting Metroliner (Reply 8):
Here's a dumb question - did any aircraft ever use more than one engine type?

IIRC, UPS'es 727's had Rolls-Royce Tays on the outside positions and they left the JT8D in the center (#2) position...

View Large View Medium
Click here for bigger photo!

Photo © Carlos Borda

Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
timz
Posts: 6161
Joined: Fri Sep 17, 1999 7:43 am

RE: Converting Aircraft

Wed Jan 16, 2008 12:59 am

IIRC, you don't recall correctly.
 
57AZ
Posts: 2371
Joined: Tue Nov 02, 2004 2:55 pm

RE: Converting Aircraft

Wed Jan 16, 2008 2:36 am



Quoting Timz (Reply 12):
IIRC, you don't recall correctly.

Correct. The enlarged air intake on the No. 2's S-duct was a requirement due to the volume of air required for the Tay to operate.
"When a man runs on railroads over half of his lifetime he is fit for nothing else-and at times he don't know that."
 
Viscount724
Posts: 19287
Joined: Thu Oct 12, 2006 7:32 pm

RE: Converting Aircraft

Thu Jan 17, 2008 2:08 am



Quoting KELPkid (Reply 11):
Quoting Metroliner (Reply 8):
Here's a dumb question - did any aircraft ever use more than one engine type?

IIRC, UPS'es 727's had Rolls-Royce Tays on the outside positions and they left the JT8D in the center (#2) position...

You're thinking of the Super 27 conversion program. A few 727s had the outer engines replaced with the JT8D-217/219 as used on the MD-80 but the original JT8D-15/17 was left in the center position. I think that's because the larger diameter fan on the -217/219 would not fit the center position without major changes. Super 27 photos below.


View Large View Medium
Click here for bigger photo!

Photo © Adam Rowden
View Large View Medium
Click here for bigger photo!

Photo © Gert Rosmann



View Large View Medium
Click here for bigger photo!

Photo © T.Laurent
View Large View Medium
Click here for bigger photo!

Photo © Samuel Schneeberger

 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: Converting Aircraft

Thu Jan 17, 2008 6:45 pm



Quoting Viscount724 (Reply 14):
You're thinking of the Super 27 conversion program.

Ah, thanks. I knew I wasn't full of crap then, just couldn't remember which 727 conversion program it was  Smile
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
CaptOveur
Posts: 6064
Joined: Thu May 06, 2004 3:13 am

RE: Converting Aircraft

Fri Jan 18, 2008 9:14 am



Quoting Metroliner (Reply 8):
Here's a dumb question - did any aircraft ever use more than one engine type?



Quoting Viscount724 (Reply 14):
You're thinking of the Super 27 conversion program.

I think this is also called a Valsan Conversion.

Also, I think the last few 727s off the line. The ones that went straight to FedEx might have been built with this feature already in place.
Things were better when it was two guys in a dorm room.
 
aeroweanie
Posts: 1577
Joined: Fri Dec 03, 2004 9:33 pm

RE: Converting Aircraft

Fri Jan 18, 2008 3:47 pm



Quoting Viscount724 (Reply 9):
The Boeing B-36 was probably the most notable with 6 piston engines and 4 jet engines.

Convair, not Boeing!

Quoting CaptOveur (Reply 16):
I think this is also called a Valsan Conversion.

Yes. Valsan did the engineering, certified it and then went bust. Goodrich/Rohr picked up the pieces and continued it as the Super 27.

Quoting CaptOveur (Reply 16):
Also, I think the last few 727s off the line. The ones that went straight to FedEx might have been built with this feature already in place.

No, Boeing would have nothing to do with the conversion. They were converted after delivery.
 
Viscount724
Posts: 19287
Joined: Thu Oct 12, 2006 7:32 pm

RE: Converting Aircraft

Sun Jan 20, 2008 2:06 am



Quoting Aeroweanie (Reply 17):
Quoting Viscount724 (Reply 9):
The Boeing B-36 was probably the most notable with 6 piston engines and 4 jet engines.

Convair, not Boeing!

Yes, sorry, you're right!
 
User avatar
HAWK21M
Posts: 29917
Joined: Fri Jan 05, 2001 10:05 pm

RE: Converting Aircraft

Sun Jan 20, 2008 3:53 am



Quoting Futurecaptain (Reply 3):
It has been said that all things considered it is cheaper to buy a new aircraft from the manufactuer then it is to do this kind of conversion and get the plane recertified for normal pax operations.

Costs matter in this field.And if the option to buy a new Aircraft is available,why spend on a mod of such nature.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
CaptOveur
Posts: 6064
Joined: Thu May 06, 2004 3:13 am

RE: Converting Aircraft

Mon Jan 21, 2008 6:54 am



Quoting HAWK21M (Reply 19):
And if the option to buy a new Aircraft is available,why spend on a mod of such nature.

The used aircraft is availible now. The new one might take months or years to be built.
Things were better when it was two guys in a dorm room.
 
Tod
Posts: 1709
Joined: Sat Aug 28, 2004 6:51 am

RE: Converting Aircraft

Mon Jan 21, 2008 4:07 pm



Quoting Aeroweanie (Reply 17):
Valsan did the engineering, certified it and then went bust.

Didn't Valsan hire Flight Structures to do the cert work?

Tod
 
airfoilsguy
Posts: 3485
Joined: Sun Oct 09, 2005 7:28 am

RE: Converting Aircraft

Mon Jan 21, 2008 8:30 pm



Quoting Futurecaptain (Reply 3):

But, if you don't want to use the plane in passenger service again...slap a GE-115 on a 747.

Why stop at 1? Put 4 on it. Would probably rip the wings off at full thrust but take off distance would probably be significantly reduced.  Smile
It's not a near miss it's a near hit!!
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: Converting Aircraft

Tue Jan 22, 2008 6:41 am



Quoting Airfoilsguy (Reply 22):
Why stop at 1? Put 4 on it. Would probably rip the wings off at full thrust but take off distance would probably be significantly reduced.

I can just see it now: The Air Planes 747 SST conversion, or the Riley Rocket 747  Silly
Celebrating the birth of KELPkidJR on August 5, 2009 :-)

Who is online

Users browsing this forum: 727glasair, ikolkyo and 17 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos